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John Moulton HomesteadGrand Teton National Park
Moose, WY
Compiled by:
The Architectural Conservation LaboratorySchool of DesignUniversity of Pennsylvania
Prepared for:
National Park Service/USDIFunding from:National Park Service/CESU Project Number: P17AC01226
TASK 1 REPORT
Conditions Assessment, Materials Characterization and Initial Treatment Recommendations for Exterior Stucco on the John Moulton Homestead
June 2018
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
Conditions Assessment 1.0Introduction....................................... 2.0 Historic Background........................... 3.0 Methodology..................................... 4.0 Preliminary Assessment 5.0 Digital Analyses.................................. 6.0 Summary Of Findings......................... 7.0Recommendations.............................
Appendices I.ConditionsGlossary.............................. II.LaboratoryTestingResults................... III. Samples Index.....................................
Drawings RectifiedPhotoElevations ConditionsDrawings SampleLocations
TABLE OF CONTENTS
14
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Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
1
1.0 INTRODUCTION
The John Moulton homestead, located in
Grand Teton National Park, is one of six
building complexes that constitute the
historic district, which was inscribed on the
National Register of Historic Places in 1997.1
Commonly known as “the Pink House,” the
Moulton homestead stands out among the
many vernacular log structures in the park
for its principle character-defining feature:
a pink-painted cement stucco exterior. The
original stucco skin and its finish date to the
construction of the building in 1938 and
together with the interior; the house may well
be the most intact historic residence within
the Mormon Row Historic District (Figure 1.1).
Given its high historical integrity, the current
condition of the exterior stucco is cause
for concern as it appears to be exhibiting
cracking, loss at the foundation, displacement,
and detachmentof the whole system from
the wooden sheathing underneath (Figure
1.2). To date, there has been no substantial
investigation into the overall condition of
the building or its painted cement stucco
skin. In order to better consider the many
possible causes of failure, this study explores
the use of non-destructive digital tools as a
method to investigate the extent, patterns,
and correlation of stucco failure to associated
intrinsic and extrinsic factors. First, the
stucco and its attachment system will be 1 No single structure on the row is individually designated at the present.
analyzed through the findings of a field-
based condition survey and a compositional
analysis of the stucco; this research mirrors
that of a traditional conditions assessment
and materials characterization methodology.
The study then considers the use of three
different digital techniques to analyze the
spatial distribution of data, which builds
upon the information collected during the
conditions assessment. These tools provide
complementary information that ultimately
renders a more thorough assessment,
while minimizing the use of invasive
physical techniques that conflict with good
preservation practice.
The principle goal for the Moulton property
is to determine the cause of the cracking in
the exterior stucco, as well as the extent of
post construction detachment. Geographic
information system (GIS) software, infrared
radiation thermography (IRT), and Structure
from Motion (SfM) photogrammetry are
tools which have the potential to supplement
more traditional modes of documentation
by furthering spatial understandings and
three dimensional characteristics that are
difficult to calculate or record by hand.
Patterns based on the comparison of the
resulting graphics suggest that unseen or
misunderstood conditions could be more
extensive than what is observed in the field
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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Figure 1.1 The John Moulton homestead, also popularly known as the Pink House. (Photo by author, 2017)
Figure 1.2 Primary deterioration concerns at the John Moulton homestead center on the evident cracking and loss of the exterior stucco. (Photos by author, 2017)
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
3
or can be communicated through typical
conditionsdrawings.Eachofthesetechniques
providesadifferentanduniqueapproachof
enhancingthetypicalmethodsofcondition
survey.Thegoalofthisstudyistoseeifthe
findingsfromthesemethodscanenhance
visiblephenomena.Thesuccessofthis
experimenthingesonthedegreetowhich
thesetechniquescanclarifytheevidenceof
deteriorationconditionsbeyondtraditional
documentation,ultimatelyrenderingthe
analysis more robust.
TheNationalParkServicecontactedthe
ArchitecturalConservationLaboratory(ACL)
attheUniversityofPennsylvaniato1)analyze
theconditionoftheexteriorstuccoatthe
Moulton homestead and 2) examine the
mechanismsofdeterioration.Whilethisstudy
beginstosatisfysomeoftheserequirements,
afullconditionassessmentandtreatment
recommendationsareforthcoming.While
focused primarily on the discussion of modern
digitaltechniquesofsurvey,anadditional
outcomeofthisstudyistheproductionof
baselineconditiondocumentationconsisting
ofaseriesofannotateddrawingsand
stuccocharacterizationandanalysis.Inthe
conclusions,futurefieldandlabresearchis
discussedaswellasotherfactorsaffecting
thelongevityofthebuilding,includinga
prioritizedlistofstabilizationinterventions.
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
4
2.0 HISTORIC BACKGROUND
The John Moulton homestead is one of
fourstructuresintheMormonRowHistoric
District;distinctforitshighdegreeofintegrity
includingintactinteriorfinishesrepresenting
theentireoccupationperiod.Whilethe
significanceoftheexterioristiedalmost
exclusivelytoitsunusualcementstucco
finish.Thischoicefortheexterior,common
for the period in many urban and suburban
contexts is unusual in this rural Mormon
communitywhereitschoiceexpressedthe
meager success of a late homesteading
family,particularlyintheJacksonHoleValley,
whereanymodicumofsuccessforfarmers
wasuncommon.Themolderingruinsof
neighboringdwellingsthatoncesurrounded
thishouseredoubleitssignificancethroughits
rarity.
2.1 Historic Context
TheJacksonHoleValley,locatedinnorthwest
Wyoming,waspartofthelateperiodof
frontierhomesteadingoftheWesternUnited
States.Sinceitssettlementinthe1890s,the
major industry in the area has been tourism.
Whilerichinnaturalbeauty,theTetonareais
resourcepoorintermsofmineralsandviable
land for agriculture. By the beginning of the
twentiethcentury,JacksonHolehadasmall
populationwhoattemptedtohomestead
andcultivatefederallandgrants.Thiswas
thecaseofJohnMoulton,whomigratedto
theburgeoningMormonRowcommunity
justnorthofJacksonin1908(Figure 2.1,
2.2).JohnMoulton,alongwithhisbrother
Thomas Alma and other emigres from Idaho
and Utah, claimed land grants to the north
ofBlacktailButte,whichhadafortuitous
combinationofdeep,well-drainedsoilswith
access to seasonal streams and shelter from
theprevailingwinds(Figure 2.3). The Mormon
Rowinhabitantsweretheprimarylocal
agriculturalresourceandthereforecritical
to the early Jackson Hole economy and they
providedfreshdairyproductsforthelocal
community and dude ranches alike. 2, 3
2.2 The John Moulton Homestead and
Vernacular Style in Jackson Hole
MostofthestructuresinJacksonHolereflect
theavailablenaturalresourcesintheregion.
Thelocalvernacularbuildingstyleutilized
lodgepolepine,atallandstraightgrowing
pine, sourced from Timbered Island at the foot
oftheTetonsandShadowMountaintothe
northeastofMormonRow.Indeed,manyof
thefirststructuresbuiltbyhomesteaderswere
12x12logcabinstosatisfytherequirements
oftheHomesteadingActof1862.Thelog2 AnnHubberandJaneneCaywood,“GrandTetonNationalParkMultiplePropertySubmission;NationalRegisterofHistoricPlacesMultiplePropertyDocumentationForm”(UnitedStatesDepartmentoftheInteriorNationalParkService,June1991),53.3RobertW.Righter,Crucible for Conservation: The Creation of Grand Teton National Park (Colorado Associ- atedUniversityPress,1982),64.
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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Grand Teton National Park
Wyoming
Montana
ColoradoUtah
Jackson
89
2689
191
26287
191287
5 Miles5 Kilometers
JENNYLAKE
LEIGHLAKE
TaggartLake
PhelpsLake
BradleyLake
StringLake
Grand Teton13,770 ft
Kelly
NATIONALELK REFUGE
TE
TO
N
R
AN
GE
Two Ocean
Snak
e Rive
r
Snak
e Ri
ver
Gros Ventre
River
Gros Ventre River
TetonVillage
Colter BayVillage
SouthJenny Lake
Moose
Moran
JACK
SON
LA
KE
Emma Matilda
GRAND TETO N
NATIO NAL
PARK
1950
Airport
Buffalo Fork River
MORMON ROW
Source: NPS
Figure 2.1 The Moulton homestead and Mormon Row are located within Grand Teton National Park, north of Jackson, Wyoming.
Figure 2.2 Contextual perspective illustration of the Mormon Row Historic District, which shows the extant structures on the row. (Historic American Building Survey, WY-152-A).
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
6
cabinwastheprimaryarchitecturaltypein
thearea,likelybecausehardwareandtools
requiredforframeconstructionhadtobe
transportedbytraintowesternIdahoand
drivenovertheTetonPass.4Thefirstnoted
instanceofframeconstructionisanaddition
toBillMenor’sstorein1900,whichindicates
thatmilledwoodwasavailableinthevalley
as early as the turn of the century.5 Frame
structuresweremorecommoninthe1910s
duetotheavailabilityoflumberproduced
atlocalcommercialsawmills,although
transportingotherbuildingmaterialsvia
4 TheOregonShortLine(UnionPacific)reachedasfarasRexburg,Idaho,by1899.ThelinewasextendedtoVictorin1912,atown25milesfromJacksonviatheTeton Pass.5JohnDaugherty,“LifeontheHomestead,”inA Place Called Jackson Hole: The Historic Resource Study of Grand Teton National Park,First(Moose,Wyo.:GrandTetonNationalPark,NationalParkService,1999),127.
theTetonPassRoadwasstillconsidered
treacherousuntiltheroadwaswidenedin
1932.6Untilthatpoint,hardwareandbuilding
materialscouldbepurchasedfrommercantile
stores in Jackson at a higher cost.7
Aftercultivatingtheirplotsofland,itwas
generallyacceptedthatthecabinsinitially
builtbyhomesteaderstosatisfythe
HomesteadingActwouldbereplacedwith
morefinishedandrefinedstructuresgiven
timeandresources.AfewoftheMoultons’
neighborsquicklyupgradedtheirhomesinthe
1910s;evenhisbrotherbuiltaframestructure
in1915.John,bycontrast,waitednearly
6JohnDaugherty,“TheTransportationFrontier,”inA Place Called Jackson Hole,193.7JohnDaugherty,“ThePioneers:HomesteadinginJacksonHole,1884-1900,”inA Place Called Jackson Hole,93.
Figure 2.3 View of the historic district, looking southwest. The Mormon Row community was situated on the Jackson Hole valley floor on the leeward side of Black Tail Butte (left). Traces of the Moulton homestead’s pink finish is visible through the aspen screen on the left. (Photo by author, 2017)
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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thirty years to construct his second home.
Aftermoderatesuccessfortheirfarmand
dairyinthe1920sand1930s,theJ.Moultons
hadtheresourcestobuildatwo-storyframe
housestuccoedwithcementin1938.The
housewasoneoftwostuccoedstructureson
MormonRow,andthefirststructureonthe
rowconstructedbyaprofessionalbuilder.8
The John Moulton homestead exterior is
decoratedwithapink-tintedcementpaintand
theraisedfoundationhasadecorative‘water
table’,inwhichthestuccohasbeenscoredto
represent stone and painted a darker purple
todistinguishitfromtherestoftheelevation.
Thewoodenwindowframeswereoriginally
painted a dark green, and the rest of the
woodenelementswerepaintedwhite.The
whimsicalstyleofthehousemayderivefrom
traditionsofdomesticstylinginthewestern
Mormonculturalsphere,whichfavored
durable and highly processed materials to
connoteexpressionofhumanpowerand
refinement.9HearsayamongtheNPSstaffand
JacksoncommunityplacesintentionwithJohn
Moultonhimself,whopurportedlyelectedto
paintthehousepinkbecauseitwashiswife’s
favoritecolor.Inall,thenewvibranthouse
wouldhavestoodoutdramaticallyonthe
valleyflooramongstthelogcabinsandnearby
frame structures alike.
8AnnHubberandJaneneCaywood,“NationalRegisterofHistoricPlacesMultiplePropertyDocumentationForm,”49.9ThomasCarter,“FrontierFashion:DomesticArchitectureandIndividualDisplay,”inBuilding Zion: The Material World of Mormon Settlement(Universityof Minnesota Press, 2015), 102.
2.3 Preservation Philosophy
OftheseveralhomesteadsinMormonRow
communityduringthe1910sand1920s,
onlysixfamiliesremainedontherowinto
thenextgeneration.10 Although Jackson and
itssurroundingcommunitieshadflourished
duringwartimeastheresultofhigherprices
foragriculturalgoods,thefollowingdecade
broughtdrought,fallingbeefprices,andtwo
devastatingfloods.Homesteadersinthevalley
could barely subsist on the meager products
oftheirland;11duringthe1930s,several
familiessoldtheirlandtotheSnakeRiverLand
Company (SRLC).12In1943,themajorityof
thevalleyfloorsurroundingMormonRowwas
incorporatedintotheJacksonHoleNational
Monument;theseareaswereconsolidated
intotheexpandedGrandTetonNationalPark
in1950.Moreover,whilethosefewfamilies
succeeded in maintaining their residency,
mostofthemsoldtheirlandtotheGrand
TetonNationalParkafter1950underleases
to lessen the economic strain of agricultural
lifeinthevalley.JohnMoultonsoldhislandto
theparkin195313afterreachinganagreement
10AnnHubberandJaneneCaywood,“NationalRegisterofHistoricPlacesMultiplePropertyDocumenta-tionForm,”53-54.11MaxwellStruthersBurt,“HomesteadandDesertClaims,”inThe Diary of a Dude-Wrangler(NewYork,:C.Scribner’ssons,1924),124-125.12 Local business people and the state legislature pressured the SRLC to put a moratorium on purchasing landfromtheMormonRowin1930,asitwastheonlyviableagricultureinthevalley.Followingthehardshipsofthelate1920s,anumberofsettlerswrotetothegovernorofWyomingtoappealthedecision.Bylate1930,theMormonRowareawasreinstatedintheSRLCpurchasing program.13CandyVyveyMoulton,Legacy of the Tetons,2ndrev.
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
8
Figure 2.4 A comparison of photographs from the early 1960s to the present confirms that the John Moulton homestead still has high integrity. The historic photo also shows how the visible the structure would have been during the period of significance when the aspens in the front yard were much smaller. (Source: Best of the Tetons, https://www.bestofthetetons.com/2014/04/08/the-moulton-barns-1963-1965/)
1965 2017
withtheparktoleasebackthelandforthe
restofhislifetime.Johnresidedinthehouse
foranotherfortyyearswithhelpfromfamily
members to maintain the structure. 14,15After
John’sdeathin1991,theMoultonfamily
relinquishedthepropertytotheNationalPark
Service.
The Moulton homestead is the most intact of
anyexistinghistoriccomplexontheMormon
Row.Lifetenantcaretakerstypicallyhad
littleinterestinmodernizingtheirstructures
becausetheyknewthattheirproperties
ed.(Cheyenne:LaFronteraPub.,2007),92.14 AnnHubberandJaneneCaywood,“NationalRegisterofHistoricPlacesMultiplePropertyDocumentationForm,”54.15CandyVyveyMoulton,Legacy of the Tetons,94.
wouldnotbeinheritedbysucceedingheirs,
so most structures remained in their historic
condition.16 Caretakers typically let their
property fall into disrepair in the later years
oftenancy.Bycontrast,thesubstantial
amount of intact historic fabric at the John
Moulton homestead complex indicates that
theMoultonsfastidiouslymaintainedthe
house(Figure2.4).In1997,MormonRowwas
inscribedontheNationalRegisterofHistoric
Places. The NationalParkServicehassince
mothballedthestructure;nomaintenance
16M.Curran,“MormonRowHistoricDistrict,GrandTetonNationalPark;NationalParkServiceCulturalLandscapesInventory”(NationalParkService,DepartmentoftheInterior,2006),https://www.nps.gov/grte/learn/historyculture/upload/Mormon-Row-CLI.pdf, 17.
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
9
hasbeencompletedsince1991aside
fromboardinguptheaccessiblewindows.
VolunteerprojectsinpartnershipwiththeNPS
haveaddressedmaintenanceofthegrounds
and outlying structures, but not the main
house.17
In summary, the singularity of the structure
derivesfromanumberofconcurrentsources.
First,itsflamboyantarchitecturalstyleand
useofcommercialconstructionmaterials
represent a rare instance of successful
homesteadingintheJacksonHoleValley
wheretheconceptof‘provingup’cameto
fruition.Itspersistingintegrityredoubles
itssignificance,particularlyagainstthe
backdropofthenearlyemptyMormonRow.
If the ruined state of the historic district is
anyindication,thisisthepivotalmoment
forNPSculturalresourcemanagerstostep
17https://www.bestofthetetons.com/2014/08/13/preservation-begins-on-the-john-moulton-homestead/.
inandproactivelyinvestinpreservingthe
original fabric of the structure. According
to the Secretary of Interior’s Standards,
“Preservationisdefinedastheactofapplying
measuresnecessarytosustaintheexisting
form, integrity, and materials of an historic
property.”18 This approach is the most
appropriate for this property since it maintains
ahighdegreeofphysicalintegrity.While
concise, this brief history demonstrates that
thestuccoiskeytoconveyingthestructure’s
significance.Whatremainsatissueisthe
physicalconditionofthestucco,andits
abilitytomaintainintegrityasadecorative
andprotectivefinishontheJohnMoulton
homestead.Thenextsectionwilldiscussthe
resultsoffieldinvestigationandlaboratory
analysisofthestuccoinordertoverify,orcall
intoquestion,theconditionofthestucco.
18AnneE.Grimmer,The Secretary of the Interior’s Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring and Reconstructing Historic Buildings(Washington:U.S.DepartmentoftheInterior,2017),2,https://www.nps.gov/tps/standards/treatment-guidelines-2017.pdf.
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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3.0 METHODOLOGY
Aconditionsassessmenttypicallyconsistsof
abriefsiteandstructuralsurvey,followedby
systematicdocumentationandassessment
ofthephysicalconditionoftheresource
basedonaccepteddefinitionsofconditions
and their pathologies. Photography, graphic
conditionsdocumentation,andtechnical
geophysical and structural reports are used
tosupplementtheseevidencesandbolster
conclusions. Historical research is pursued to
confirm,orchallenge,aswellassupplement
interpretationofthesite’spresentcondition.
3.1 Field Survey
Aconditionsurveywasconductedoverthe
course of three days, from October 20 to
October 22, 2017. Once on site, the team
conductedabriefpreliminarysurveyofthe
sitetoidentifytheprimarydeterioration
conditionsandstrategizehowtobest
document them in spite of a number of
disadvantagesinthefield.19 Assessment
wascarriedoutfromthegroundaroundthe
structure.Theinteriorofthebuildingwasnot
accessibleduringthefieldsurvey.
Uponinvestigation,theteamidentifiedthat
theprimarydeteriorationconditionaffecting
the cement stucco is cracking. Secondary
conditions,includingbiologicalgrowthand
discoloredordeterioratingfinishes,were19 These are discussed further in a succeeding limitationssection.
presentonthesurfaceofthestuccobutwere
veryinfrequent.Somenotehasbeenmade
oftheseonelevationdrawingsaspartofthe
conditionsassessment.
a.Limitations
Fieldsurveywaslimitedbyanumberof
factorsthatrelatetounexpectedpractical
difficultiesinthefield.Weatherconditions,
includingfreezingrain,snow,andgustywind,
madethefieldassessmentprocesslessthan
ideal.Allobservationsweremadefromgrade
becausescaffoldingandladderswerenot
practicalinthegivenweatherconditions
(Figure 3.1).Conditionsofthestuccoitself
madeassessmentdifficult.Thestuccowas
toothicktoreliablyidentifyvoidsthrough
ataptest.Finally,thesurveyconsistedof
tworesearcherscompletingtheassessment
overthecourseofthreedays.Thenumberof
limitationsforcedtheresearcherstoprioritize
recordingofprimaryconditionsinthefield,
andtakeotherformsofdocumentationthat
couldsubsequentlybeanalyzeduponreturn
totheUniversityofPennsylvania.
The high integrity of the stucco also acted
asahindranceforfieldinvestigation.While
conditionslikecracking,discoloration,
andpaintlossarevisibleandcanbeeasily
recordedusingtraditionalmeans,other
conditionssuchasblinddetachmentand
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
11
corrosionofthemetalreinforcementswould
nothavebeenpossibletothoroughlyrecord
withoutsignificantinterventions.Duetohigh
integrity of both the stucco and the interior
finishes,forexample,itwasnotpossibleto
blindly probe or expose the underside of the
stuccoinordertoexaminetheattachments
or detect detachment from the underlying
sheathing.
b.ConditionDrawings
Independentdrawingswerecreatedtodepict
theextentofconditionsforeachelevation.
Forthisfieldproject,fieldconditiondrawings
servetwopurposes.Theyallowforbetter
synthesisofinformationinsubsequent
analysesaswellasprovidingabaselinefor
futureconservation.FortheJohnMoulton
homestead,itisparticularlypertinentto
diminishorremoveunnecessaryvisual
informationthatstandoutinphotography—
suchaslargecracks,andthevariationin
surfacetextureandcolor—inordertobetter
understandthespatialrelationshipand
patternofconditions.
Duetotheenvironmentalfactors,initial
conditionsdrawingsweremadeoffsiteusing
rectifiedelevationphotostodrawvisible
cracks.20Thesedrawingswerethentaken
intothefieldtobeconfirmedandannotated
basedonvisualfieldinspection(Figure 3.2).
20BasedonarchitecturalelevationlinedrawingbasefilescreatedbyA&EArchitectsofMissoula,MT.
Figure 3.1 Access to the upper part of the south, west and north elevations was limited due to poor conditions. A ladder was used to collect samples and make close range observations. (Photo by author, 2017)
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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Alongeachcrack,orportionsoflinesegments,
a‘size’notewasaddedtocharacterizethe
approximatewidthofthediscontinuity
(Figure 3.3). The team members agreed upon
general categories to depict size, ranging
fromextra-smalltoextra-largeorabnormal;
thisinformationisincludedintheconditions
glossary;seeAppendix I. The extent of loss
wastracedandhatched.Displacement,or
areaswhereeithersideofthecrackarenot
onalevelplain,werealsonoted.Secondary
conditionswerealsonoted,whichare
detailedinageneralglossarywithphotosand
definitionsasacompaniontothedrawings.
Theseinclude:
• Discolorationandstainingoftheplaster,
duetomoistureoranimalactivity.
• Biologicalgrowth,includingmossesand
lichen, on the stucco surface.
• Lossofpaintedfinish,howeverthedegree
towhichthishadprogressedwasunique
toeachelevation,rangingfrommost
deterioratedonthesouthelevationto
intactontheeastelevation.
Tocreatethefinaldigitizedconditions
drawings,thefield-annotatedarchitectural
elevationswerescannedandthenewdigital
fileswerere-rectified.Thesefileswerethen
attachedtotheexistinglinedrawingfiles
usingAutoCAD.Polylineswerethentraced
overthefield-corroboratedcracks,each
assignedtodifferentlayersaccordingtothe
sizeannotationaccompanyingthecrack
segment.Afinalsetofdrawingsareincluded
in Appendix II.
c. Photography
Photoswereusefulprimarilytoillustrate
theconditionsobservedinthefield.In
architecturalconservation,photographycan
support the analyses and hypotheses that are
madebytheconservatorbutalsocanenhance
otherkindsofdocumentationinthisreport,
aswellasbeusedasabaselinefromwhichto
judgedeteriorationinthefuture.
Aseriesofphotographsweretakenduring
fieldsurveytodocumenttheconditionsof
the structure and site. The purpose of these
photographscanbebroadlysortedintofive
categories:
• Architecturalsurveyphotographs:These
photographscaptureelevationsandthe
relationshipsbetweenthem,aswellasthe
detailsofthesitecontextthatcanaffect
thepreservationofastructure.
• Conditionsphotography:Detailphotos
thatexhibitavarietyofdifferent
conditionsforthepurposesofbuildinga
visualglossary;seeAppendix I.
• Infraredradiationthermography(IRT)
photos:ThermalimagestakenwithaFLIR
C2CompactCameraofeachelevation,
aswellasclose-uppartialphotosto
bestitchedtogetherlatertoimprove
resolution.
• Photogrammetry:Thisprocesswhichrelies
onaseriesofoverlappingphotographs
whicharesubsequentlyalignedand
convertedtoadensepointcloudin
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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Figure 3.2 Preliminary conditions drawings were confirmed in the field; all observations were made from grade. (Photo by C. Magill, 2017)
Figure 3.3 Cracks were confirmed and then annotated according to size, extra small to ex-tra large; those which were not evident in photos were traced onto elevations in the field.
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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post-processing to capture the three
dimensionalshapeoftheelevationsin
order to detect detachment of the stucco.
3.2 Survey Results
Basedonthesurvey,theprimarydeterioration
conditionsaffectingthestuccoinclude
cracking, loss, displacement, and detachment
ofthesystemfromthewoodensheathing
underneath;secondaryconditions,suchas
discolorationandlossofthepaint,were
infrequentanddeterminedtobesuperficial
andnotcontributingtorisk.Basedon
preliminarydiagnosticsandresearch,the
cracksfallbroadlyintotwocategories.First
arecrackswithdiscerniblelikelycauses,
whicharetypicaltofailureofcementitious
materialsordevelopinresponsetoinstallation
orstructuralmovements.Othercracks,like
theseriesoffinecracksinanorthogonal
patternonthewestandsouthelevations,
arelikelytheresultoferrorsininstallation
(Figure 3.4).Adramaticcrackonthesouth
elevationindicatesthatthestuccosystem
isdetachingfromthewoodensheathing
beneath,buttheextentofthisconditionis
not apparent. Loss has occurred at the base
ofthestructure,wherethetensilestrengthof
thestuccohasbeensurpassed.Whetherthe
causesoftheseconditionsarestatic,dynamic,
orworseningcanbesurmisedatthistime
based on complementary analyses, but must
beconfirmedinthefieldwithmonitoring
protocols.
Theresultofthesurveyisasetofdrawings
withtheextentofconditionsdrawnandkeyed
photographsthatindicatetheseverityof
deteriorationphenomena.Thesearetypical
documentationforarchitecturalconservation,
and can be easily read by a resource manager
or professional. They are useful in that they
arecomparable:thisdrawingsetprovides
baselinedocumentationagainstwhich
succeeding assessments can be compared
todetermineiftheconditionisworsening
orstatic.Butaspreviouslysuggested,these
drawingsbythemselvesdonotindicatethe
extentofunseenconditions,suchasblindor
incipient detachment.
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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Figure 3.4 Fine orthogonal cracks evident on the south elevation are likely the result of differnetial thermal expansion of the metal reinforcements. (Photo by author, 2017)
Grand Teton National ParkTask 1 Report: Stucco Assessment
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4.0 PRELIMINARY ASSESSMENT
Thisfollowingsectionisanassessmentof
eachofthepossiblecontributingpathologies
affectingthestuccoandthestructure,
synthesizingtogetherevidencesfromfield
investigations,historicproductliterature,
andlaboratoryanalyses.Theinformation
gainedfromlaboratorytestingisrelevantas
itcancontributetothedocumentationand
conditionassessmentofanyconservation
reportaswellasinformaboutthematerial,
bothasitwasoriginallyappliedandasitisin
its present state. In this instance, analyzing the
stuccocansubstantiateordismisstheinitial
pathologyhypothesesthatcallsintoquestion
theconditionofthecementmatrixandthe
embedded ferrous metal reinforcement.
SeveralNPSemployeesandconservation
professionals,eachofwhomhaveaunique
andintimateknowledgeofthestructure,were
askedforinitialopinionsabouttheprimary
factorscontributingtothedeteriorationof
the stucco.21Theinstallationandassemblyof
thestuccoiscalledintoquestionbytwoof
the hypotheses put forth. Other phenomena
includethemechanismsoffailurethataffect
thecementmaterial,metalattachment
21 Respondents included Shannon Denison (formerly NPSGRTE),BetsyEngles(formerlyNPSGRTE),JeffOlsen(formerlyNPSGRTE),JimMcDonald(A&EArchitects),MattMorgan(A&EArchitects),MichaelHenry(PE,AIA;UPenn, lecturer), and Frank Matero (UPenn, professor of architecture).
system, frame structure, and site. Figure 4.1
liststhesehypotheses,alongwithtestsor
methodsrequiredtoconfirmthemasprimary
contributorstodeterioration.
Literatureresearch,fieldsurvey,conditions
graphics, and laboratory material analysis can
substantiateordismissthemajorityofthese
theories,andadditionalmonitoringmaybe
abletoconfirmtheresults.Thesemethods,
however,cannotfullyestablishtheareaof
detachment,deformation,andweathering
damage—theextentofwhicharecriticalto
determineinordertoestimateriskoffailure.
Probing or exposing the interface of the
stuccoandframecouldbegintoconfirmthese
conditions,butduetothehighintegrityof
thestructure,itisimperativetousemethods
that minimize damage to the historic fabric
asmuchaspossible.Othernon-destructive
methods,includingultrasonictestingand
laserscanning,couldpotentiallybenefitthe
surveysinthefuture;however,thesearenot
currentlyavailabletotheACLandcanbecost
prohibitive.
4.1 Comparison to Contemporary Product
Literature
AsidefromaNationalRegisternominationand
documentationfromtheHistoricAmerican
BuildingSurvey,norelevantresourceswere
foundwhichdiscussthebuildingoftheJohn
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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StructuralFoundation
Hypothesis Evidence(s) MethodofConfirmation
Relic roots on the east side of the structure had undermined the foundation.
Diagonal cracking, detachment
Historic research
Rodents undermining thefoundation.
Diagonal cracking, detachment
Observation,monitoring
Unevensettlementofthefoundation.
Diagonal cracking, detachment
Research, monitoring
Attachment
Meshisbuttedratherthanoverlapping.
Rectilinearcracking Survey
Undersized nails usedtoattachmetalreinforcement.
Detachment Survey
Differentialthermalexpansionbetweenmetal reinforcement andcementand/orwoodframe.
RectilinearcrackingResearch on material properties
Differentialexpansionoffurring strips.
Rectilinearcracking Survey,literatureresearch
Corrosion of metal reinforcement.
Cracking, lossSampleexamination,fieldconfirmation
Cement
Damage due to exposure;thermalcycling, hygric cycling, freeze-thawcycling.
Cracking,particularlyonthesouthandwestelevations.
Laboratory analysis
Environment Earthquakedamage. Diagonal cracking Literature research
Figure 4.1 Theories of deterioration collected from site managers and knowledgeable preservation professionals.
Grand Teton National ParkTask 1 Report: Stucco Assessment
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Moultonhomesteadindetailoritscondition
whenitenteredintothecareoftheNational
ParkService.Contemporarysourcesthat
discusstheinstallationofexteriorcement
stuccoareessentialinthiscase,asthey
canhelptoelucidateerrorsinapplication
orinstallationthatmaybecontributing
tothedeteriorationofthestucco.Several
theoriesinthisveinhadbeenputforward
byprofessionalsaspotentialcontributorsin
Figure 4.1,andthesewillbereferredtoin
thissection.Thefollowingsectioncompares
theobservationsofthestuccoassemblyat
theMoultonhomesteadtothatwhichwas
prescribed in the literature of the period.
Descriptionsandillustrationsregardingthe
systemofconstructionarebasedoncommon
constructiondetailsforframestructures,with
somedetailsaddedbasedonobservations
fromthefield.
Inthefirsthalfofthetwentiethcentury,
hydrauliccementswereconsideredtheonly
material acceptable for exterior plastering due
totheirdurability,appearance,andeffective
waterproofing.Industriallyproducedartificial
cementwasincreasinglyaccessibleinthelate
nineteenthandearlytwentiethcenturiesdue
tothedevelopmentofthecontinentalrail
networkandexpandingdomesticproduction
intheUnitedStates.Bythe1920s,Jackson
Holewasstillrelativelyisolated.Goods,like
the cement used on the Moulton homestead,
werecarriedviarailroadanddrivenoverthe
Teton Pass to Jackson to be sold at one of the
generalstoresintown.Contemporarycraft
treatises22 and product literature explained
thetechniques,tools,andmaterialsnecessary
toapplycementstuccoandanticipate
potentialpitfalls.
a.SystemExamination
Despitetherelativedifficultyinprocuring
building materials in rural Jackson Hole, the
reinforcement substrates and stucco at the
John Moulton homestead appears to meet
recommendedspecificationsintheliterature,
withonecriticalexception.Contemporary
PortlandCementAssociationliterature
describestheidealinstallationofstuccoon
aframestructureas,inorderofassembly:
woodensheathingnailedtowallstuds;a
moisturebarrierattachedtothesheathing
surface;wovenwirelathreinforcementpanels
attachedtothesheathingoroffsetfrom
the surface by furring nails (Figure 4.2). This
providesthesubstratereinforcementforthe
cement stucco to be applied in a three-coat
system.Asevidencedbytheareaoflosson
thesouthelevation,thestructurehasdiagonal
woodsheathingtosupportthestuccosystem
(Figure 4.3)withatarpapervaporbarrier
attachedtothesheathing(Figure 4.4).
Furringnailswereplacedatadistancefrom
oneanothertoavoidcracking,althoughthe
patternisdifficulttodiscernfromthissmall
22WhetherornottheMoultonswouldhavehadaccesstotheseresourcesisnotknown,butthesearedocumentscontainclarifyingdetailswhicharesometimesabsentfromproductliterature,includinghelpfultechniquestoimprovethedurabilityandworkabilityofexteriorstucco.
Grand Teton National ParkTask 1 Report: Stucco Assessment
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Figure 4.2 Section detail, based on product literature and observations at the site; this system provides a suitable substrate reinforcement for the stucco to be applied. (Drawn by author, 2018)
VaporBarrier
WireLath
FurringDevice
DiagonalWoodenSheathing
2”WallStud
FinishCoat/Pigmented Finish
BrownCoat
Scratch CoatNail
Grand Teton National ParkTask 1 Report: Stucco Assessment
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areaofobservation;seeFigure 4.3.23 Furring
devicesatthehomesteadmatchadevice
advertisedinaPortlandCementAssociation
manualfrom1929,whichsuccessfullyoffset
thenailheadsandwirereinforcement1/4in.
fromthesurfaceofthesheathingallowingthe
cement to thoroughly coat and protect the
ferrous metal from corrosion (Figure 4.5).24
Whilethenailswerenotmeasured,aphoto
taken from behind an area of displacement
witharigidborescopeshowsthatthenails
weremostlikely13⁄8in.inlengththat
matches the length of nails recommended
intheproductliterature,disprovingthatthe
nailsmaybeundersizedandcontributingto
detachment of the system.
Thepotentialflawinconstructionisnotthe
attachmentofthemetalreinforcementtothe
sheathing,butrathertheinstallationofthe
mesh.Basedonfieldobservation,itappears
thatthewovenferrouswirelathpanelswere
notoverlappedtherecommended1in.but
buttedtogether,perhapsinanattemptto
economize the materials (Figure 4.6). To form
arigidsurfaceonwhichtheplastercancure,
thereinforcementshouldhavebeenlappedat
least1in.attheedgestoformacontinuous
networkacrosstheentiresurface.Metallic
lathswereoftensecuredattheedgesofthe
sheetstothejoists,whetherwithwire,fixing
23Nailswerepreferabletofurringstripsthatcancauseareasofweaknessinthestucco,resultingincracking.24AfurringdevicewaspresentinasamplesentbytheNPSstafftoPhiladelphia.Thestuccohadalreadybeendetachedfromthesouthelevation.
nails,orstaples;theextenttowhichthiswas
doneisunknown,butitmaynotbesufficient
to secure the panels together. Therefore, the
meshpanelsmayactasindependentfields
that expand and contract under thermal
conditionsratherthanactingasacontinuous
surface, likely the cause of at least some, or
possiblyall,ofthefineorthogonalcrackson
thesouthandwestelevations.
4.2 Materials Characterization
a.TestSelectionandSamplingMethodology
For the purposes of this project, laboratory
testingandanalysisisconfinedto:
• Opticalmicroscopy(petrographic
examinationandcrosssectionalanalysis)
tocharacterizetheweatheredcondition
ofthecementmatrixandpossiblyidentify
the source of the aggregate in the stucco.
• Porositycharacterizationtoestablish
theavailableporespaceinavolumeof
material.
• Mechanicaltestingtodeterminethe
abilityofthestuccotoresistbrittlefailure
through three-point bending.
• Testingtodeterminethepresenceand
relativeamountofsalts(nitrates,sulfates,
and chlorides) in a sample.
Samplelocationswerechosentoensureat
leastonerepresentativesamplefromeach
elevation.Tominimizethevisualimpactof
missingmaterial,samplesweretakenlargely
from the base of the structure near areas that
Grand Teton National ParkTask 1 Report: Stucco Assessment
John Moulton Homestead
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Figure 4.4 Evidence of the underlying vapor barrier, visible through a crack on the south eevation. (Photo by author, 2017)
Figure 4.3 Section detail, based on product literature and observations at the site; this system provides a suitable substrate reinforcement for the stucco to be applied. Hap-hazard holes from the furring nails indicate that the lath was not attached using furring strips. (Photo by author, 2017)
FURRING NAIL HOLES
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Figure 4.5 Image from 1929 PCA literature exhibiting acceptable furring devices as well as nail sizes for furring out lath. The device indicated matches that found at the Moulton homestead. (from “Plasterer’s Manual for Applying Portland Cement Stucco and Plaster.”)
Figure 4.6 Only one layer of reinforcement is visible in cross section along the vertical edge of a crack. (Photo by author, 2018)
Grand Teton National ParkTask 1 Report: Stucco Assessment
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werealreadyexhibitingdamage,crackingor
loss.Asaresult,thedataobtainedintesting
mayrepresentthemostdamagedcondition
ratherthanageneraloverallconditionofthe
cement stucco due to proximity to ground
moisture,snowaccumulation,andexposureto
weathering.
Oncelocationswereidentified,sampleswere
detached from the structure mechanically
using a hammer and chisel (Figure 4.7).
Eachsamplewasnumberedsequentially
withlocationsannotatedinfieldnotes.
Photographsweretakenateachsampling
locationandtheselocationsaremarkedon
drawingsattheendofthisreport.Appendix III
hasanindexofeachsample,withbulksample
photographs,adetaileddescriptionand
primarykeywords,andanotationisincluded
that indicates the test applied.
b.TestingResults25
Boththecementitiousmaterialandthemetal
reinforcement,individuallyandasacomposite
unit,areinrelativelygoodcondition.Many
ofthelaboratorytestresultsshowthatthe
stuccoisstillrobust,bothphysicallyand
chemically.Inextremeenvironments,cement
asamaterialwillinevitablyloseitsmaterial
integrityandtheseconditionsmustbetreated
seriously. Some of these future pathologies
canbeextrapolatedbytheobservations
made in these tests. These are not presently
soseriousthattheyarecontributingtothe
present failure of the stucco.
In all, despite eighty years of exposure, the
cementpasteisstillwelladheredtothe
aggregateanddoesnotshowsignificant
damage due to thermal or hygric cycling.
Thereisevidenceofsurfacemicrocrackson
boththeexteriorandposteriorsurfaces;these
areas are more thoroughly carbonated than
the surrounding matrix. In some cases, these
cracksalsoalignedwithsmallunderlyingvoids
likelytheresultofmoistureinfiltrationand
freeze-thawcycling(Figure 4.8). The cement
matrixsurroundingthewovenwirelath
doesnotshowsignificantphysicalstressthat
accompaniesexpansivecorrosionproducts
orthermalcycling.Voidsevidentnearthe
25FurtherinformationinAppendix II.
Figure 4.7 J. Hinchman detaches a sample from an area of existing damage on the east elevation using a ham-mer and chisel. (Photo by author, 2017)
Grand Teton National ParkTask 1 Report: Stucco Assessment
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metal reinforcement are likely from errors in
applicationratherthandamage.Theresults
from the mechanical tests suggest that the
stuccoisquitedurableinflexuralbending,
whichmeansthatthecompositematerialis
ingoodconditionandasignificantamountof
forcewouldhavebeenrequiredtocausethe
cementtoruptureanddisplace,asisevident
onthebaseofthestructurewherethereis
nowloss.Insamplesthatdemonstratea
modulusofelasticitybelowtheaverage,it
is possible that the adhesion of the cement
matrixtothewireclothwasmoreinfluential
thantheactualconditionofthestuccoitself,
asvoidsdiminishedthetensilestrength
impartedbythewire.26
Theembeddedwovenwirelathreinforcement
datestothe1930s,beforetheadventof
galvanizedsteelandcorrosionresistant
coatings;asthesystemwasoriginally
designed, the alkalinity of the cement should
inhibit corrosion products from forming.
Overtime,however,theprocessofcement
carbonationtakesplacewherebythecement
matrixcombineswithatmosphericcarbon
dioxide to form calcium carbonates. In a
neutralenvironment,themetalelements
aremoresusceptibletocorrosion:thisis
concerning, as the metal becomes more
susceptibletobreaking,andmayinduce
spalling of the cement material due to
corrosion jacking. The Moulton homestead 26ConversationwithDr.AlexRadin,oftheLaboratoryforResearchontheStructureofMatterattheUniversityofPennsylvania.
cementsamplesdemonstratevariabledepths
ofcarbonationinpetrographicexamination,
whichmayberelatedtothedegreeof
exposure. The metallic reinforcement system
showssomeevidenceofferrouscorrosionbut
this does not appear to be inducing physical
damage to the surrounding cement matrix.
Whereobservable,thefurringdevicesand
wirelathlooktohaveviablecrosssection
(Figure 4.9).Therelativelylowlevelsof
corrosionandcementcarbonationcould
beduetothelowlevelsofporosityinthe
cement.27, 28
Inthefuture,however,thecementmaterial
shouldbemonitoredforsignsofdeterioration
relatingtothermalcyclinganditsrelated
pathologies. One such pathology is corrosion
jacking,inwhichtheferrouscorrosion
productscanswellinvolumeandexert
force on the surrounding concrete, stone,
masonry,etc.,whicharereinforcedwith
metalcomponentswhichultimatelyleadsto
damage.29Carbonation,forexample,isan
inevitablephenomenonforcementandwill
eventuallyleavethemetalreinforcements
exposedtodeterioration.Whilesaltattackwas
notpositedasapotentialcontributortothe
deteriorationofthestucco,salttestingstrips
indicate that the stucco contains moderate
27ConversationwithMichaelHenry,PE,AIA,lectureronbuilding pathology at PennDesign.28Inferredfrompercentporositycalculationsbasedontherateofwaterabsorption;seeAppendix II.29DavidWatt,Building Pathology: Principles and Practice,2nded.(Oxford;BlackwellPublishing,2007),120-21.
Grand Teton National ParkTask 1 Report: Stucco Assessment
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Figure 4.9 Cross section of furring device which shows some evidence of ferrous corrosion. Despite eighty years of exposure, the metal still has a significant amount of heathy cross section. Magnification 20x. (Photo by M. C. Boileau, 2018)
Figure 4.8 Cross section of a subsurface void directly connected to a surface crack, which shows that moisture can percolate through hairline cracks and exert force on the material with cycling temperatures. Magnification 50x. (Photo by M. C. Boileau, 2018)
Grand Teton National ParkTask 1 Report: Stucco Assessment
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amountsofnitrites(25to50mg/L)and
sulfates(>1500mg/L),30thelattertypicalfor
Portlandcement.Evidenceofcrystallinesalt,
however,werenotobservedinpetrographic
examinationnordothesamplesdemonstrate
damagepatternsconsistentwithsaltattack,
althoughinafewinstancessubfluorescence
wasobservedwithinthecementmatrixand
on the building paper. Soluble salts can readily
undergocrystallizationcyclesinenvironmental
conditionswithvaryinghumidityand
temperature, as is the case in Jackson Hole.31
Otherpotentialpathologieswhichcanaffect
cement, include inappropriate aggregate
thatisphysicallyorchemicallyincompatible
withcement.Forexteriorstucco,riversand
istypicallythebestaggregateduetoitslow
clay content.32InWyoming,decomposed
graniteandtufarockwasconsidereda
suitablesubstitute.33 Sub-angular grains
werepreferredforexteriorplasterwork,as
the shape deters shrinkage from occurring.34
Theaggregateobservedinthesamplesisa
coarse, sub-angular mixture of stable and inert
30 See Appendix II.31Dissolvedsaltscancrystallizeandexertpressureonporewallsinthematerial,inducingmechanicaldamage;whenrelativehumidityincreases,thesaltsre-dissolveand can be transported further into the material utilizingthemechanicaldamageasanextendedporenetwork.32J.T.Sawyer,Plastering(Shaftesbury:Donhead,2007),31.33PortlandCementAssociation,Proportioning Concrete Mixtures and Mixing and Placing Concrete.(Chicago:Portlandcementassociation,1916),9,https://catalog.hathitrust.org/Record/100029668.34JeremyP.Ingham,“Mortar,Plaster,andRender,”
alluvium,whichislikelytobelocallysourced
fromeithertheSnakeorGrosVentreRiver.
Noevidenceofalkalisilicareaction(ASR)or
otherdeteriorationpathologiesaffectingthe
aggregatewereobserved.
4.3 Structure and Environment
Thebuildingsubsurfacecontextiscritical
toanalyzingthepresentconditionofthe
stucco and the structure as it might explain
localizedfailureonthesouthelevation.Site
conditionsthathavedestabilizedpartofthe
southeastfoundationwereputforthasa
major contributor to the diagonal cracks and
detachment of the stucco from the underlying
sheathing.Otherenvironmentalfactors,such
asweatherconditionsandseismicactivityalso
fallunderthiscategoryofinvestigation.
a. Historic and Contemporary Uses
Althoughthefoundationisnotpartofthe
stucco,itsoverallconditionhasadirectimpact
onthelongevityoftheentirebuilding.Infact,
thereissomeevidencethatsuggeststhat
the most serious, albeit localized problems
withthestuccomaybedirectlylinkedtothe
conditionofthefoundation.Whilebriefly
toucheduponhere,thisissuewiththe
foundationwillbediscussedfurtherinthe
conclusions as it has both a direct impact on
the future of treatment and helps to support
someoftheideasputforwardaboutthe
conclusionsofthenon-destructiveanalysis.
Theconditionofthefoundationcanbein Geomaterials Under the Microscope(London:MansonPublishingLtd.,2013),137–62,https://www.sciencedirect.com/science/book/9780124072305,154.
Grand Teton National ParkTask 1 Report: Stucco Assessment
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inferred from a number of sources. This report
doesnotpurporttobeacomprehensiveor
finalizedanalysisoftheconditionsaffecting
thefoundationbutdiscussestheinferences
thatcanbemaderegardingitscondition.
AccordingtotheNationalRegisternomination,
otherstructuresintheMormonRowdistrict
arebuiltonfoundationwallsmadeofconcrete
ornativestone,butthesearetypicallyshallow
enoughthattheentirestructurecanbuoyantly
restontopofthealluvialclays.TheJ.Moulton
houseissimilarlybuiltonaconcretewall
foundation,butacellarunderthesouthwest
portionofthestructurethatextendsbelow
the frost line renders that part of the house
rigid. The north and east parts of the house
arecantileveredandappeartohavemoved
differentiallytothesouthwest,likelycausing
thelargediagonalcracksevidentonthesouth
andnorthelevations(Figure 4.10). The Reed
MoultonHouse,whichislocatedtothenorth
of the John Moulton property on the Jackson
Moran Road, is an excellent comparison for
thispoint.Thehousedoesnotappeartohave
adeeperfoundationorcellarthanacement
foundationwallandthereforeitsexterior
stucco does not exhibit the same diagonal
cracks.Whetherthismotionistheresultof
freeze-thawofthesoilorsubsidenceshould
bedeterminedwithfurthermonitoringand
the assessment of a structural engineer.
Historicphotographswereusedtoanalyze
previousconditionsofthehouse,including
landscaping and contemporary uses. Proximity
of trees and bushes to the base of the
Figure 4.10 Plan of the John Moulton Homestead basement. (Historic American Buildings Survey, WY-152-A)
Grand Teton National ParkTask 1 Report: Stucco Assessment
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structuremaycontributetodestabilizationof
thefoundationduetorootjacking,whereby
the root system undermines and destabilizes
thefoundationwall.Theroleoftherelic
tree roots on the east side of the structure
similarlyrequiresfurtherresearch:itwas
suggested in one comment that the tree roots
couldhaveactuallystabilizedtheeastside
ofthefoundationanddeterredmovement,
butnowthatthetreeisgone,35 the roots are
disintegratingandthefoundationisfreeto
subside (Figure 4.11). A thorough structural
35Thetreeisevidentinthe1997HABSphotosandhasbeencutdownby2014,accordingtothedatestamponphotos found online.
investigationisneededtocorroboratethe
precisecauseoffoundationmovement,asit
meansthedifferencebetweenmovementthat
isstableandcyclingandmovementwhichis
eccentricandworsening;bothofwhichwould
greatlyaffecttheconservationtreatments
implemented.
b.SeismicActivity
Recordsoflocalseismicactivityisalso
presented in this research, as ground
disturbancesmaybecontributingto
deteriorationconditions.TheTeton-
Yellowstoneregionhasahighlevelof
Figure 4.11 HABS photos from 1997 reveal trees and bushes encroaching on the east and south sides of structure, potentially impacting the stability of the foundation. (Historic American Buildings Survey, WY-152-A)
Grand Teton National ParkTask 1 Report: Stucco Assessment
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seismicity due to faults in the surrounding
regionandtheYellowstonehotspot.36 In
theTetonregion,severalthousandsmall
tomoderatemagnitudeearthquakeshave
beenrecordedinthelastthirtyyears;37 these
rarely exceed magnitude 2.5.38 It is possible
that loads from mild seismic tremors could
becontributingtothecrackingphenomena
at the John Moulton homestead. The Reed
Moulton residence, north of the John
Moulton homestead, does not exhibit similar
displaced diagonal cracking in its exterior
stuccocharacteristictolateralloadsinduced
byearthquakes(Figure 4.12).39Eitherthe
stuccoattheotherhousewasinstalledafter
damage occurred to the stucco at the John
Moulton homestead or, if the R. Moulton
stucco is contemporaneous, large cracks at the
Pink House are likely not the result of seismic
activity.
c. Climate
Thermal expansion and moisture gradients
are the most common causes of cracks in
concrete.Initialstrainisinducedasthe
cementcoolsanddries,butsubsequent
fluctuationsintemperatureandmoisture36BonnieJ.PickeringWhiteetal.,“SeismicityandEarthquakeHazardAnalysisoftheTeton-YellowstoneRegion,Wyoming,” Journal of Volcanology and Geothermal Research188(2009):277.37Ibid,783.38“SearchEarthquakeCatalog”,accessed12April2018,https://earthquake.usgs.gov/earthquakes/search/.39TheNationalRegisternominationisunclearastowhenthestuccowasappliedtothestructure.Thehousewaslikelybuiltbypreviousownersinthe1910sor1920s,beforetheJohnMoultonhomestead.
cancausethedifferentmaterialsinthe
assembly to expand and contract. 40,41 These
discontinuitiesaretypically1-2mmwideand
havelittletonoeffectonthedurabilityorthe
strength of the concrete.
TheJacksonHolevalleydisplaysextreme
temperaturevariations.TetonCountyis
classifiedasASHRAE169-2006Climate
ZoneNumber7SubtypeB,verycoldand
dry(43.666065,-110.664857).Duringboth
thesummermonthsandwintermonths,
theaveragedailytemperaturecanfluctuate
betweenthirtyandfortydegreesFahrenheit
(Figure 4.13). 42, 43Freezingconditionsand
temperaturefluctuationsmayinducedamage
tothecement,whichleavestheunderlying
ferrous metal reinforcements exposed to
atmosphericconditionspotentiallycausing
corrosion. The R. Moulton home is again a
goodcomparison;theexteriorofthestructure
islikewisecoveredbyhairlineandsmall
cracks,whichconfirmsthatcementitious
stucco forms small cracks under the strain
ofthermalcycling,manyofwhichreseal
athigentically.
40Concretetypicallycontracts0.37mm/mduringset.41DavidOdgers,ed.,Concrete,vol.8,PracticalBuildingConservation(London:EnglishHeritage,2012),75-76.42“TemperatureExtremes,Annual,Moose(486428)-WyomingStateClimateOffice,”accessedApril2,2018,http://www.wrds.uwyo.edu/temperature/extremes/486428-Annual.html.43Averagesummertemperaturesvarybetweenlowsof37-40°Fandaveragehighsof75-80°F.Inthewinter,bycontrast,theaveragedailyhightemperatureisbetween22and30°Fandtheaveragelowcanreach0to10°F.
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Figure 4.12 The stuccoed exterior of the Reed Moulton home does not exhibit diagonal cracking, as would be expected from earthquake damage or foundation subsidance. There is evidence of similar orthagonal cracking on the south and north (pictured here) elevations of the R. Moulton home. (Photo by author, 2017)
Figure 4.13 The average temperatures on the valley floor demonstrate extreme seasonal variations; a normal daily temperature cycle can exhibit 25-40 degrees change. (Source: Wyoming Water Resources Data System/State Climate Office)
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Meanannualsnowfallinthevalleycanreach
13to16ft.44Astudyofsnowdriftsobserved
attheBarBCDudeRanchinGrandTeton
NationalParkfoundthatsnowtendedto
flowwiththewindandaccumulateonthe
northsideofthestructure,butthiswasless
dramaticforgableendsthatareperpendicular
towinddirection.45 Because the gable end of
thestructurefacesthewindperpendicularly,
somesnowaccumulationlikelyoccurson
the north side of the Moulton homestead
atthebaseandontheroof.Thedifferential
accumulationshouldnotbesignificantly
unequalbetweenthenorthandsouthofthe
structureifBeckman’sobservationsfrom
the Bar BC ranch hold true on the other side
ofthevalley.Photographicdocumentation
inthewinterwouldbeusefultoappreciate
howhighthesnowaccumulatesagainstthe
stuccoonthenorthelevation.Whereversnow
accumulates at the base of the structure, the
stuccoisincontactwithasourceofmoisture
and therefore exposed to related damage.
TheprevailingwindsintheJacksonHole
Valleyblowfromsouthtonorth,although
BlacktailButteshouldshieldtheJohnMoulton
homestead. The stucco is completely exposed
onallsidestoweather,withlittleprotection44ChristopherA.Davey,KellyT.Redmond,andDavidB.Simeral,“WeatherandClimateInventory,NationalParkService,GreaterYellowstoneNetwork”(FortCollins,CO:NationalParkService,2006),13.45ChristineL.Beckman,“EvaluatingtheDisplacementModes and Associated Risks of Stacked Log Structures”(UniversityofPennsylvania,2013),https://repository.upenn.edu/cgi/viewcontent.cgi?arti-cle=1547&context=hp_theses.
affordedbytheaspentreesimmediatelyto
theeast.Thesurfaceofthesouthelevation
receivesboththebruntofsolargainaswell
aswinterstorms.Acombinationofdirect
sunlightandexposuretothewindarethe
causeofdramaticpaintlossandpossible
fadingonthesouthelevation.
4.4 Summary of Assessment
Based on these preliminary analyses, half of
theoriginaldeteriorationhypotheseshave
beenfullyeliminatedwhileothershave
alsobeendrawnintoquestion(Table3.14).
Whilethesedonotapproximatespecific
areaswherethestuccoisatrisk,itiscritical
inaconditionsassessmenttodeterminethe
causesofpathologiesandwhetherornotthey
areactiveandworsening.Treatingafflicted
areaswhenthecausesofdeteriorationare
stillactivecanriskacceleratingdamage
andwastingresourcesoninterventions
thatareultimatelyineffective.Treatment
isineffectiveandpotentiallyharmfulifthe
mechanism of failure is not understood. All of
theseissuesdiscussedaboveareimportant
tosystematicallyconsideraspotentially
contributingfactors.Thosewhichremainare
eachapotentialcandidateforthecauseof
failureandyetthequestionremainshowto
identifyifanyorallofthesearefactorsof
equalweight.Mostoftheconclusionsthat
havebeenreachedthusfarhavebeenbased
oninvestigationsthatlimitedtheamountof
destructivecontactwiththestucco.Without
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doingmoredamage,alternativesneedtobe
consideredtohelpthisprocessofnarrowing
downthecontributingfactors;thisiswhere
theuseofnon-destructiveevaluationand
testingshouldbeconsidered.
StructuralFoundation
Hypothesis MethodofConfirmation Contributing?
Relic roots on the east side of the structure had undermined the foundation.
Historic research Potentially
Rodents undermining the foundation.
Observation,monitoring Potentially
Uneven settlement of the foundation.
Research, monitoring Potentially
Attachment
Mesh is butted rather than overlapping.
Survey Likely
Undersized nails used to attach metal reinforcement.
Survey
Differential thermal expansion between metal reinforcement and cement and/or wood frame.
Research on material properties
Likely
Differential expansion of furring strips. Survey, literature research
Corrosion of metal reinforcement.
Sample examination, field confirmation
Cement
Damage due to exposure; thermal cycling, hygric cycling, freeze-thaw cycling.
Laboratory analysis
Environment Earthquake damage. Literature research
Figure 4.14 Revisedlistofdeteriorationhypotheses.
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5.0 DIGITAL ANALYSES
Developingamethodologytocomparethe
resultsproducedbythethreedifferentnon-
invasiveapproachesofassessmentchosenfor
thisthesisrequiresunderstandingthevalue
oftheirrelationship.Geographicinformation
systems(GIS),infraredthermography(IRT)
image analysis, and photogrammetry each
havetheirstrengthsandlimitationstoindicate
areas of unseen damage. The graphics
producedbyeachsoftwarecanshowthe
spatialdistributionofconditions,whether
cracks, temperature, or three-dimensional
shape, but none of the results are absolute
or can independently indicate damage.
Anindividualgraphicbyitselfisoftennot
sufficienttocorroboratethepresenceofa
conditionduetoavarietyoflimitationsof
thattool.Overlayingtheresultantgraphics
from each of the three systems together can
helpsubstantiate(orcallintoquestion)areas
ofpresumeddeteriorationbyshowingthe
similaritiesordifferencesbetweentheresults
of the tests.
5.1 Aims
Initialresearchquestionsforeachelevation
aretwofold:1)toidentifytheextentof
deformationanddetachmentand2)to
analyzethepotentialriskthatexposure
toweathercouldposefordeterioration
ofthecementand/oritsferrousmetal
reinforcements.Theresultsthatfolloware
basedonacomparisonoftheresulting
graphics,whicharetheninterpreted
throughmaterialbehaviorsand/orstructural
observationsfromthefield.Thesuccessof
thesegraphicsandsourcesofpotentialerror
dependonthedeteriorationconditions,
qualityofdatagatheredinthefield,and
fieldlimitationsuniquetoeachelevation.
Forthisreason,thefollowingdiscussionis
organizedaccordingtoelevation.Thesouth,
westandnorthelevationarediscussedand
havecorrespondingillustrations.Thermal
imagesforeastelevation,however,didnot
showsufficientvariationstobeusefulfor
comparison.Followingabriefdescription
oftheevidentpatternsisadiscussionof
the likely causes or contributors to these
phenomenaandananalysisofpotential
deteriorationrisks.
a.SouthElevation
Theprocessofinformationcollectionfor
photogrammetry and infrared thermography
inthefieldwasquitethorough,asthesouth
elevationhadpreviouslybeenidentified
asanareaforsignificantconcern.A
photogrammetricmodelwasconstructed
fromaseriesof96photostakentocapture
theelevationbothstraightonandobliquely;
theresultingmodel,therefore,hashighdetail
and is more likely to accurately portray the
planarityofthestucco.Limitationsthatcould
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haveaffectedtheresultingmodelarethose
whichhaveaffectedtheentireconditions
assessmentprocess;namely,photographshad
to be taken from grade. The photos for the top
oftheelevationweretakenfromapoorangle
and,asaresult,willbeoflowerresolution
and disposed for error than the base of the
structure.Foroptimalphotogrammetrywork,
severaloverlappingphotosarerequiredto
showbothdetailsandbroaderswathsofarea
aswellasheadonandangledphotographs.
Thesouthelevationfacesdirectlysouth
and is unobstructed, so the majority of
theelevation’ssurfacecanreceivedirect
sunlight.46
From a comparison of these graphics,
anchoredbyobservationsinthefield,wecan
makethefollowinghypotheses:
1. Areas of likely attachment and
detachment, according to relative
temperature (Figure 5.1). Theareabelow
theleftcorneroftheeasternwindowon
thefirststoryisknowntohavedetached
stucco;intheinfraredthermograph,this
area is notably cooler than the adjacent
plaster.Itwasdeterminedinthecourse
offieldinvestigationsthattheplasterto
theleftandabovethisarea,alongside
thewindowframe,appearedtobebetter
attachedtotheunderlyingsheathing.
The temperature gradient runs from
coolertowarmerwherethestuccois46Theonlyexceptionistheareadirectlyundertheeaves.
betterattached.Therefore,itcouldbe
assumedthatareaswhichhaveahigher
surface temperature may be the result of
thermal transfer from the sheathing and
theinteriorofthestructure.Whilethis
assumptioniswellframed,thereareother
factorsinhouseconstruction,whichcould
alsoproducecolorvariationinthethermal
image, including changes in the thickness
ofthestucco,variationsininsulationdue
tosettlingorimproperinstallation,and
moisturepenetrationjusttonameafew.
2. Correlating bigger crack sizes with possible
areas of detachment (Figure 5.2). Crack
patternscanoffersuggestionsaboutthe
failureofthestuccoandthosepatterns
can easily be exploited in ArcMap
whererunningdensitiesisarelatively
easyprocess.UsingaGISsoftware,
ESRIArcMap,thespatialdistribution
ofthecrackscanbeconvertedintoan
image(ordensityraster)whichisbased
onconcentrationsofoccurrencesfor
aselectedfeature.Wherethereisa
clusteringofpoints,thatareawillhave
ahighervaluecomparedtofewerpoints
in other areas, producing an image of
hotspotsbasedonthestatisticalanalyses
ofthespatialrelationshipsbetween
points. A series of density maps based
onsizesforthesouthelevationwere
generatedinordertolookforsimilarities
betweenthedistributionofdensehot
spotsandtemperature.Areaswithcooler
temperaturesonthesouthelevationthat
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25° F60° F
Figure 5.1 Hypothesis: Areas that have lower temperature are associated with detachment. Areas where the weight of the stucco is not adequately supported by nails.
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Figure 5.2 Hypothesis: Bigger cracks and areas of cooler surface temperature are associated with or indicative of unseen detachment. Possibility of water intrusion through the crack to wet the nails, vapor barrier, and wood sheathing; deterioration could be obscured by the stucco.
25° F60° F
DENSITYOFM,LANDXLCRACKS.
The bigger cracks map can show the distri-bution of cracks which are associated with structural movement and shear forces on the stucco; these tend to occur at the base and corners of the structure, as well as corners of openings.
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arecoincidentwithareasthathaveahigh
density of medium, large and extra-large
cracks.Whilethissystemworksforthe
southelevation,itdoesnotseemtoapply
aswellfortheotherthreeelevations
wherethermalvariationseemstobe
much smaller. The end result is that the
comparisonoftheIRandGIScanshow
thatthereisapossiblecorrelationbut
itfailstoexplainwhythiscorrelation
is not consistent on the other sides of
thehouse.Theseareaswerefurther
investigatedusingthephotogrammetric
model;severalcrosssectionswerecutin
theseareasandoverlaidinordertosee
ifdisplacementwasoccurringandthe
extentofthiscondition(Figure 5.3). It
wasthroughtheuseofphotogrammetry,
and the usefulness of 3D data, that
providesapossibleclueastowhythe
patternsdescribedabovedon’tseemto
beconsistentwhencomparingthesouth
withtheotherthreeelevations.While
thesouthelevationshowsasignificant
shiftoutofplaneinseverallocations,the
other three sides do not. It is through the
comparisonofthethreedifferenttypesof
digitalassessmentthatthepatterncanbe
uncovered.
3. Surface areas with a higher density of
cracks and warmer temperature are likely
to still be attached to the sheathing. Based
onthefirstobservation,warmerareas
ofthestuccosurfacearelikelybetter
attachedtotheunderlyingsheathing.A
comparison of the infrared thermograph to
theGISdensitygraphicsrevealsthatthese
highlighted areas are strikingly similar
toareaswherethereisahighdensityof
extra small and small cracks (Figure 5.4).
Thispatternwouldimplythatareaswhich
haveahigherdensityofcracksarebetter
attachedtotheunderlyingsheathing.
Therefore, it could be possible that
attachmentofthestuccotothesheathing
inducesorencouragestheformation
Figure 5.3 Cross section from photogrammetric model shows above that detachment (in red) on the south elevation could be more extensive than observed in field investigation. Still of photogrammetric model on the right indicates with area of cross section.
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Figure 5.4 Hypothesis: Areas with a higher density of cracks could indicate areas where stucco is still attached to the sheathing. Possible areas where ferrous reinforcement is corroding, as microcracking and surface cracking are correlated with deeper carbonation of the cement. Freeze thaw action and salt efflorescence, due to greater potential for water intrusion.
DENSITYOFALLCRACKS.
25° F60° F
In this graphic, the value for each crack is equal (‘1’) as it is difficult to objectively apply differing values to different sizes of cracks.
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ofsmallcracks.Whilenotasalarming
as the large cracks or detachment, it is
importanttoconsidertheimplications
of micro cracks for the fabric and its
potentialfordeterioration,basedonthe
observationsfromthelaboratorytesting
section.Whilethesesmallercracksare
likelyconfinedtothesurfaceandexpose
lesscrosssectiontowaterinfiltration,
boththecrosssectionandthinsection
samplesrevealthatmico-cracksareoften
accompaniedbyevidenceofatmospheric
andwaterinfiltration.Materialssampled
fromexposedareasrevealedsurfacemicro
cracksandmuchdeepercarbonationthan
less exposed counterparts. Once concrete
has carbonated, the material is no longer
sufficientlyalkalinetodetercorrosionof
metalreinforcements.Whiletheseareas
couldbebetterattachedtothesheathing
beneath, the reinforcement in these areas
could be more predisposed to corrosion
andlossofviablesection.Thesearealso
areaswithagreaterpotentialforwater
transmission and therefore are more likely
toexperiencedamageduetofreeze-thaw
cyclingandsaltcrystallization.
b.WestElevation
Thereisalackofstrongcorrelationbetween
theresultingthermalimageandcrackdensity
graphics (Figure 5.5). The highest crack density
gradientfallsintoareasthathavealower
temperature;thisisoppositetoobservations
fromthesouthelevationwherehigher
densitiescoincidedwithhighertemperatures.
Thehighdensitiesoflargercracksoccursnear
thefoundationofthestructure,areasthat
aredistributedacrossagradientofwarmer
and cooler temperatures in the infrared
thermograph.
Environmentalconditionsandcontingencies
couldaffectthedataorexplainthelackof
correlationsintheimagery.Forone,the
geometry of the ell could be encouraging
anunevenwarmingofthesurfacethat
wouldskewtheresultsfromtheinfrared
thermographs. Another possibility is that
detachment,whichissuggestedbythe
photogrammetricsectiononthesouth
elevation,doesnotoccuronthisparticular
elevation;displacementofthesouthcorner
demonstratesthattheplasterisstillattached
to the sheathing, and that the sheathing
andpossiblytheframeitself,ismovingaway
fromthefoundation.Incontrasttothesouth
elevation,however,itsgraphicsignatureis
unknownandthelackofcorrelationbetween
thecrackdensitiesandthermalimagesmeans
thatitisdifficulttopostulatewhereitcouldbe
occurring.
DuetothislackofcorrelationbetweentheGIS
andthermalimagesforthewestelevation,a
directed approach to select areas, as on the
southelevation,wasnotpossible.Areasof
plasterjustaboveandbelowthewindows,
thewidestexpansesofmaterialonthis
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DENSITYOFALLCRACKS DENSITYOFM,L,XLCRACKS
Figure 5.5 The thermal images were taken at midday, when solar raditation had only warmed the south elevation of the west ell skewing the distribution of temperatures across the surface of the west elevation.
19°F30° F
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elevation,wereselectedtocreatetwocross
sectionstolookforpossibledeformationof
thestucco.Asthedrawingindicates,neither
sectionrevealssignificantdeflectionor
detachment of the stucco (Figure 5.6). A slight
bending is apparent on the right side, but
this is more likely the result of a poorly built
photogrammetry model than actual damage
tothestructure.Theplanarityofthewest
elevationcombinedwiththelackofclear
corolationbetweenthedensitymapsand
thermal images implies that detachment does
notoccuronthiselevation,ortothesame
degreeasthesouthelevation.
c.NorthElevation
Thedistributionofcrackdensitiesfortwo
setsofcrackscalculatedintheGISarenot
concentratedinafewlocationsastheywere
onthesouthandeastelevations(Figure
5.7).Theseincludeboththeentiretyofthe
cracksandaswellasonlythebiggercracks
(Medium,Large,andExtraLarge).Instead,the
cracksappeartobewelldistributedacross
thesurfaceoftheelevationinbothgraphics.
Biggercracksarealsomoreprevalentonthe
northelevationthanonothers,asseveral
ofthecoincidentdensitiesbetweentheAll
Cracks and Bigger Cracks graphics suggests.
This is to be expected as the cracking is more
likelytheresultofstructuralmovementrather
than thermal or hygric cycling. There does
notappeartobeacorrelationbetweenthe
crack density graphics and thermal images. It
iscriticaltoconsideragaintheenvironment
and exposure for this part of the structure.
Thenorthelevationhadreceivednodirect
exposure to sunlight, so the thermal transfer
predominantly comes from the interior
Figure 5.6 Cross sections from the west elevation appear to be plane. The stucco on the west elevation of the ell is likely to be in good condition and not detached because it may not be undergoing the same amount of movement as the main structure. Further testing with a higher resolution IR camera will be required to confirm this condition.
TOP
BOTTOM
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DENSITYOFALLCRACKS DENSITYOFM,L,XLCRACKS
Figure 5.7 The similarity between the density graphics for all cracks and bigger cracks confirms that failure on this elevation is result of structural movement rather than thermal or hygric cycling. Neither density map has a strong correlation to the thermal image, implying that detachment is not present. Photogrammetry will confirm.
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of the structure, the ambient exterior air,
andtheground.Thethermographshowsa
distinctcoolergradientatthebaseofthe
structure,whichislikelytheresultofsnow
accumulation.
Ahigh-densitypointcloudwasconstructed
usingsevenphotos,alltakendirectlyfacing
themainnorthelevation;duetothelow
number of photographs, this model has
thepoorestresolutionofthesetandisless
accurate.Theresultingcrosssectionappears
tobeconcave,whichislikelyduetoalack
ofphotostakenfromobliqueangles(Figure
5.8).Nonetheless,thesectiondoesnotreveal
significantirregularitiesthatwouldsuggest
detachment of the stucco.
5.2 Discussion of Results
Priortotheconditionsassessment,most
professionalshadassumedthatthepatternof
cracksacrosstheentirehousewasevidence
ofafailingstuccoaswellasphysicalevidence
ofauniformproblemwiththeentirehouse,
requiringalarge-scaletreatment.Since
treatmentisirreversible,andcanintroduce
damagethroughinvasiveapplications,a
cautiousapproachisoftenthebestsolution.
Theoverlayofdigitalanalyses,described
above,waspursuedtoprovidemore
informationabouttheconditionofthestucco.
Ultimately,thisanalysisdidnotindicateareas
ofunseendeteriorationwithcertainty,but
rathertheresultswillguideinvestigationsin
subsequentfieldvisits.
Figure 5.8 The photogrammetric model for the north elevation appears to be concave, which is likely due to a lack of photos taken from oblique angles. Nonetheless, the sections do not reveal significant irregularities that would suggest detachment of the stucco. The thermal signatures are more likely to be the result of external environmental factors than revealing characteristics about the stucco.
TOP
BOTTOM
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Anexaminationofthisareainthedigital
graphicsestablishesaseriesofvisual
correlations.Fromthese,aseriesof
furtherdeductionsaremade,whichcan
berationalizedbyobservationsfromthe
fieldinvestigationand/orknowledgeof
architecturalconservators.Thisinitialproof
ofconceptprocessofanalysiswasneither
straightforwardnorstrictlyscientific,while
possibletodoso,andreliedontheiterative
processofvisuallycorrelatingsimilaritiesand
thenusingknowledgeofdeteriorationcauses
andeffectstointerpretthepatterns.
Onenotabletakeawayfromthedigitalanalysis
is that there appears to be inconsistencies
whencomparingtheresultsofthesouth
facadewiththeresultsoftheotherthree
elevations.Theprocessofgraphicsoverlay
wasthemostsuccessfulforthesouth
elevation,wheretheanalysisfollowedaseries
ofsuppositions,establishedusingknown
areasofdeteriorationandconfirmedinthe
field.Whencomparingtheresultsofthe
north,west,andeastsides,whichhaveno
largecracksthathavedisplacement,theyall
seemtohavesimilaritiestoeachotherbutnot
to the south. The inconsistent results of the
southelevation,whencomparedtotheother
threeelevations,mayshowthatthesouthside
of the building is in fact an anomaly and that
truefailure—failurewhichcompromisesthe
survivalofthesurvivalofthestucco—isnot
reflectedinthesmallercracksbutinsteadis
onlyassociatedwiththelargestcrackswhich
display shear displacement.
Theconclusionsoftheanalysis,whichinvoked
not just the digital, but also the historical
research, and the laboratory analysis, suggests
thatthecracksacrosstheentirehouseare
notindicationsofafailingsystembutmaybe
duetothethermalexpansionandcontraction
cracks similar to monolithic concrete, stucco
andplaster.Areviewofthehistoricliterature
showsthattheinstallationprocesswas
consistentwiththemanufacturer’sguidelines
oftheday,andlaboratoryanalysisshowsthat
thestuccoiswellformulatedanddisplays
limiteddecayatthemicrolevel.Ifthe
hundreds of smaller cracks are not a threat
tothelongevityofthestuccoorthestructure
thenperhapstheevidencefoundinthedigital
assessment supports a more focused plan for
conservationthatlimitsinitialtreatmentto
onlythelargestcracksonthesouthelevation.
Thefoundationshiftingposesagreaterthreat
to the stucco, as it induces detachment and
lossofsectiontosupporttheweightofthe
systemasitpeelsawayfromthewooden
surface.Thesmall,yetextensive,cracking
patternseenacrossallelevationshaslittleto
dowiththismoredeleteriousphenomenon.
5.3 Next Steps
The possibility of this digital comparison
systemnotworkingisveryplausible.This
methodwaslesssuccessfulonthenorth,
south,andeastelevationsfortwopotential
reasons.First,theoverlayofconditions
is diminished due to inferior thermal and
photogrammetric data. The poor input data
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could be remedied in the course of future
investigation,therebyimprovingresolution
andconfidenceparametersforinferences
to be established. In fact, the hope is to
doadditionalthermalimagingonthe
structureusingamuchhigherresolution
IRcamerathatwasnotinitiallyusedinthe
2017assessment;thecameraisbothmore
expensiveanddifficulttotransport,butthe
additionalinformationascertainedwiththis
methodisworthwhile.Anotherbarrierin
establishingpatternsmayalsobeattributed
toalackofknownareasofdetachment;
inthecaseofthesouthelevation,thiswas
criticalforcreatinginferences.Although
detachmentiswhatisbeingsoughtoutin
this analysis, a proof of concept approach
suchasthisrequiressomethingonwhich
tobasetheresults.Neitherthenorth,east,
norwestelevationsdemonstrateobservable
instancesofthisconditionsincethesurfaces
arenotopenlycompromisedandtaptesting
hasprovenhighlyinconclusive.Anareaof
detachment could be established through
limitedprobinginafuturesitevisitifthere
wasstrongevidencetosuggestacandidate
areawhereopeningthehistoricfabricwould
beworthwhile.
Withthatsaid,drillingwouldberequiredfor
thepurposesoftreatment.Withoutoutward
evidenceofdetachment,alternativesare
alwayswellaccepted,especiallyifthereis
somebasisfortheirsuccess.Thenotionthat
thesystemdidnotworkatallontheother
threeelevationsisnotwithoutmerit.The
process, as applied to the north, east, and
westelevationswouldsimplyneedtobe
morenuancedanddependonunknownsbut
evidencecouldbedrawnbasedonusingthe
same process. The result is that areas on the
otherthreeelevationscouldbeidentifiedand
subsequentlyfurtherinvestigated.Blindly
drillingtodetectthisconditionisnotan
option,asitrecklesslyintroducesdamageto
thestucco.FurtherNDTanalysisisneededto
begintoidentifyareasofpossibledetachment
ontheseelevations,orconfirmthatthis
conditiondoesnotaffecttheseareasofthe
structure.
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6.0 SUMMARY OF FINDINGS
ThetaskagreementbetweenGrand
TetonNationalParkandtheArchitectural
ConservationLaboratoryattheUniversityof
Pennsylvaniaaddressesthecharacter-defining
exterior stucco on the exterior of the John
MoultonHomestead.Principalobjectives
includeestablishingthecompositionofthe
stucco,itsapplication,performance,and
causesoffailureinordertobegintodevelop
stabilizationrecommendationsandapilot
treatmentplantopreservetheexteriorstucco.
Thisthesisaddressesthefirstofthesegoals
throughavarietyofavenuesthatarecommon
toconditionassessments.Siteinvestigations
andlaboratoryanalysisprovethatthestucco
is indeed Portland cement based, of local
manufacture, and presently has good physical
integritydespitethenumberofcracksevident
on the surface of the structure. A comparison
of the contemporary product literature to the
stucco system demonstrates that the most
deleteriouspathologiesaffectingthestuccodo
not emanate from the feature or system itself.
From a long list of site- and structure-based
hypothesesinitiallyputforthaspotentially
contributingtothefailureofthestucco,a
fewlikelyphenomenahavebeenselectedto
investigatefurther.Theseinclude:
1. Foundationmovementandsubsidence,
whichhascontributedtotheformationof
large diagonal cracks and displacement of
the stucco, and
2. Differentialthermalexpansionof
the stucco and embedded metal
reinforcements,whichcausesmalland
hairlinecrackstoform;theorthogonal
patternlikelyrelatestoimproper
installationofthesectionsofwovenwire
lath,butthiswillbeconfirmedinfurther
fieldexamination.
The second part of this report focused on
analyzing and comparing digital graphics to
approximatetheextentofunseenconditions
thatposearisktothecontinuingintegrity
of the stucco. Detachment of the stucco
systemfromthesheathingisonlyobservable
onthesouthelevation,andwhenthisarea
wasprobedwithaborescopeduringfield
assessment it had been assumed that the
expanseofdetachmentwaslimitedtothe
immediate area surrounding the crack. Using
amethodologythatcombinesGeographic
InformationSystem(GIS)analyses,infrared
thermography (IRT), and photogrammetry,
the extent of detachment, at least for the
southelevation,appearstobemuchlarger
thanpreviouslyobservedinthefield.Similar
analyseswereattemptedonthewestand
northelevations,buttheresultswere
inconclusiveduetoenvironmentalfactors,
informationcollection,andthelackofknown
deterioration;itispossible,however,that
detachmentdoesnotaffecttheseareasof
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thestructure.Movingforward,testprobe
locationswillbeselectedonthebaseofthe
southelevationtoconfirmdetachmentinthe
areas suggested by this methodology. Further
studyoftheotherelevationsshouldtakeplace
tolookfordetachmentonotherelevations.
These measures could include using a higher
resolutionIRcameraandaprotocolofactive
sensingwithcontrolledexternalheatsources.
Thedensitygraphics,coupledwithlaboratory
analysis of the composite stucco, also
canindicateareasofpotentialriskwhere
thestuccoismorelikelytobeaffectedby
waterandatmosphericintrusion.Inthe
future,deteriorationintheseareascould
besubstantiatedwithothernon-destructive
tools,includingahigh-resolutionthermal
camera.Thesegraphicsprovideaprioritized
mapwithwhichtostartfutureinvestigation.
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7.0 RECOMMENDATIONS
Thefollowingisapreliminaryoutlineof
therecommendedinterventions;theseare
organizedbythedeteriorationmechanism
addressed.
I.Stucco:
1. Detachment:Beforeanystabilizationof
theplasterbegins,themovementofthe
foundationneedstobeexaminedbya
structuralengineer.Anystabilizationor
conservationinterventionsperformed
on the stucco should only take place
afteranengineerhasconfirmedthat
thefoundationisstable.Ifdifferential
movementisstilloccurring(either
cyclicallywiththefreeze-thawofsoils
orduetosubsidence)themovement
couldrendertheinterventionsineffective
and detachment could progress, or the
introducedinterventionsmightcause
further damage to the stucco.
Oncethefoundationhasbeenstabilized,
the detachment of the stucco needs to be
addressed.Asitwasinitiallyinstalled,the
furringnailswouldhavehadenoughgrip
intotheunderlyingwoodsheathingto
supporttheweightofthestuccosystem.
Because some of the nails in the system
havedisengagedfromthesheathing,itis
possiblethatthegravityloadonthestucco
could exceed the shear strength of the
nails.Theconservationplanshouldinclude
methodswithwhichthestuccocould
be supported and reintegrated into the
underlying frame. If moisture has entered
behindthestucco,itisalsoconceivable
thatthewoodensheathinghasbeen
compromisedbyrotandinsectattach.
Thiswouldcauseareasofthestucco
attachmenttofail.
2. MoistureandSolarProtection:While
itmaytakesometimetoacquirefunds
to contract an engineer and introduce
stabilizationmeasures,moisturecontrol
interventionsareminimal.Inthe
meantime,measuresshouldbetaken
toweatherizetheareasoflosswhere
woodenelementsareexposed.The
primaryfunctionofthestucco,afterall,is
towaterprooftheexteriorofthestructure
toprotecttheunderlyingwoodenframe
frommoistureandotherenvironmental
impacts that could compromise the
structural integrity of the building. The
mostobviousinstanceisthesouth
elevation,wherelossanddetachmenthas
exposed the sheathing underneath. The
cornersofthestructurewherelosshas
occurred should be checked for exposed
end grain, and similarly treated.
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A pilot treatment program should include
materialsandprocedurestofillthecracks
inmoreexposedareastodeterwater
intrusionandpotentiallyslowcarbonation
of the cement and corrosion of the metal
reinforcements.Furtherresearchwillbe
conductedtofindaphysicallycompatible
materialthatwillbeminimallyinvasiveand
notdisruptthevisualaestheticofthestucco.
Wherenecessary,reattachmentmethodsalso
need to be considered to supplement failed
attachmentsinwaysthatareinvisibleand
compatiblewiththecurrentsystem.
Indirect moisture control measures also
include altering the site elements that retain
moistureandcontributetothedeterioration
of the stucco. A French drain system should
be installed around the base of the structure,
ideallyafterallfoundationstabilizationhas
been completed. This includes laying a trench
thatwoulddirectwaterawayfromthebaseof
thestructuretoanirrigationditch.
II.Finishes:
1. Analyzetheappliedpaintedfinishesof
thestuccotoidentifyitscompositionand
alteration.
2. Perform performance tests to ascertain
its physical-mechanical integrity including
adhesion to the substrate, cohesion of
the layer (chalking) and photochemical
alterationfromfading.
3. Researchtreatmentoptionsforthe
aboveandperformdurabilitytests
usingacceleratedweatheringmethods
(weatherometer).
Finally,alloftheaboveproposedtreatments
are to be implemented in a selected pilot
treatmentareaonsiteandallowedto
weatherfornolessthanoneyearpriorto
reassessment.
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Condition: CrackA discontinuity in an architectural surface or wall painting, resulting in a visible separation of one part from another, that extends through one or more layers.
Extra Small (XS) (<0.005 in.)
Small (S) (<0.025 in.)
Medium (M) (<0.050 in.)
Large (L) (>0.050 in.)
Extra Large (XL) (Cross section exposed)
XSS
M
LXL
Graphic:
PRIMARY CONDITION
Appendix I: CONDITIONS GLOSSARY1
1 Conditions definitions based on “Deterioration Sources” and “Deterioration Phenomena” in EwaGlos European Illustrat-ed Glossary of Conservation Terms for Wall Paintings and Architectural Surfaces (2016) edited by Angela Weyer (Span-genberg: Michael Imhof Verlag GmbH & Co.)
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Condition: Biological GrowthColonization by living organisms on an object which can lead to damage and deterioration. Growth can include simple bacteria and lichens as well as more complex plants and animals.
SECONDARY CONDITION
Condition: DetachmentSeparation of the plaster system from the wood substrate, visible along cracks where displacement is occuring.
Graphic:
+
−
Positive
Negative+−
Condition: LossA missing part of an architectural surface which affects its integrity.
Graphic:
Loss
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SECONDARY CONDITION
Condition: SoilingAccumulation of extraneous material on a surface leading to discoloration.
Condition: ModificationNon-original material, historic or contemporary, which shows subsequent modification.
Condition: DarkeningA change in the surface color due to a decrease in hue. Darkening can be the result of a local presence of humidity.
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i.TestSelection
ASTM C1764-12, Standard Test Methods for Non Metallic Plaster Bases (Lath) Used with Portland
Cement Based Plaster in Vertical Wall Applications,containsaseriesofbasictestswhichcanapproximate
theperformanceandmechanicallimitationsofaPortlandCementBasedPlasterunderavarietyoftest
conditionsandexposures.Theseincludemeasuringtheabilityoftheplastertowithstandtransverseand
verticalloads,aswellascharacterizingtheembeddedlathorfurringwithintheplasterandabilityofthe
fastenerstowithstandfailure.Thescaleofthetestsinthisstandardwasdesignedfortestingcommercial
market rather than historic materials. Some of the tests employed to characterize the cement stucco
havebeenadaptedfromstandardsdevelopedforothermaterials,asthestandardrequiresfabricating
largetestframesandpanelsofcementstucconotsuitableorrealisticfortestingsmallsample.
ii.PotentialSourcesofError
Forwaterabsorptionandthreepointbendingtestsasinglelargepieceofstucco,already
detachedfromthestructure,wasdividedintosamplecoupons.1Bothteststraditionallyrequirealarge
volumeofmaterials,butobtainingsamplesfromavarietyoflocationswoulddamagetheintegrity
ofthestuccoandisnotinkeepingwithpreservationethic.Conductingtestsonstuccofromasingle
sourceratherthanmultiplesourcesintroducesadegreeofpotentialerrorasthetestresultsarenot
representativeofthestuccoforthewholestructure.Thispointisofparticularimportanceasthe
mechanicalandchemicalcharacterforcementoneachelevationcouldbedifferentduetofield-mixing.
Additionally,bothsamplesaretakenfromneargradesoitcanbeexpectedthatthesematerialsmay
haveahigherdegreeofdamagethanotherstuccomaterialsonthestructureduetoproximitytoground
moisture,faunalactivity,andvisitors.
1SamplesforwaterabsorptionwerecutfromJMH23,alargestuccopiecefrombaseoftheeastelevationwhichwasfoundalreadydetachedfromthestructure.MaterialformechanicaltestingwassenttotheUniversityofPenn-sylvaniabyGrandTetonNationalParkstaffinMarch2018;thepiecehadfallenoffofthesouthelevationandbeenstored in the kitchen of the John Moulton homestead.
Appendix II: LABORATORY TESTING
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iii. Petrographic Analysis
ASTMC856-17, Standard Practice for Petrographic Examination of Hardened Concrete,
describesthemethodologyforpreparingandexaminingcementsampleswithastereomicroscopeand
polarizedlightmicroscope.Thinsectionanalysiscancharacterizethephysio-chemicalcompositionand
deteriorationstateofacementmaterial,typicallyforengineeringandconstruction-relatedinvestigation.
Forhistoricpreservation,thesetestscanserveanumberofusefulpurposes:
• Determining the number of layers and their thicknesses.
• Identifyingthetypeofsourceofaggregate
• Identifyingthetypeofbinder:Descriptionofthecementitiousmatrix,includingqualitative
determinationofthekindofhydraulicbinderused,degreeofhydration,degreeofcarbonation
ifpresent,evidenceofunsoundnessofthecement,presenceofsupplementarycementitious
materials,andthenatureofhydrationproducts.
• Identifyingthepresenceofmineraladditions,suchaspigments.
• Quantifyingthematerialspresenttoestimatethemixproportions.
• Assessworkmanship.Determinationofeffectsofuseofdifferentconcretemakingmaterials,
forming,andmoldingprocedures,typesofreinforcement,embeddedhardware,etc.
• Identifyingdefects.
• Diagnosingdecaymechanismsandassessingthelevelofdeterioration.Determinationofwhether
theconcretehasbeensubjectedtoasulfateattackortoearlyfreezing,orotherharmfuleffectsof
freezingandthawing.Alkalireactivityoftheconstituentparts,eitherwithcarbonateorsiliceous
aggregate.
EightsamplesweresenttoNationalPetrographicService,Inc.,alongwithannotated
photographsanddescriptionsforhowtocutandpreparesamples;adescriptionofthesesamplesand
theirlocationsisinFigure II.1.Theorientationofthethinsectionswasdeterminedbyvisualandstereo
microscopicexaminationtobeperpendiculartoplasterlayers.Areaswheremetalplasterbacking
wasevidentwerenoted,andsomeofthesampleswereorderedtobecutonornearthesefeatures
toexaminethestructureofcementmaterialsinproximitytothemetalmesh.Sampleswerecutand
polishedusinganoil-basedlubricanttoensuresaltefflorescence,ifpresent,wouldnotbedamaged
duringsamplepreparation.Standardthinsectionswerepreparedforpetrographicexaminationwitha
polarizedlightmicroscope.Thesectionsweremountedontoglassslideswithclearepoxy;fivereceived
glasscoverslips,whichimproveopticsduringexamination.Threesamplesdidnotreceiveglasscover
slipsforSEMtestingatalaterdate.2
The samples examined are all similar in terms of arrangement plaster coat layers. The samples
followtheprescribedthreecoatsystemtypicallyusedinplastering:coarseorscratchcoat,followedby
thebrowncoat,andthenthefinishcoat.OnlyJMH18and20wereanomalous,astheyarebothmissing
adistinctcoarsecoatlayer;thisislikelyduetoerrorinapplicationandtherespectivelocationsofeach
2 JMH 03, 17, and 23.
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Test Sample No. Location Notes
JMH 03 SouthSampletakenfromdisplacedcrack(+)onsoutheleva-tion.Pinkfinish.
JMH 12 North
Stereomicrographshowsananomalouswhitesub-stanceunderandwithinthepaintlayer,possiblysalts.Nitratestriptestingmightconfirm,alongwiththinsectionexamination.Purplefinish(base).
JMH 16 SouthSamplecontainsferrousmesh;thinsectiontakenadja-centtowire.Purplefinish(base).
JMH 17 East Purplefinish(base).
JMH18North,West
Curvedsample,takenfromthenorthwestcorneroftheelladdition.Pinkfinish.
JMH 20 North,EastSampledfromundertheeaveontheeastelevation.The bulk sample has poor interlayer adhesion, perhaps duetofaultyapplication/installation.Pinkfinish.
JMH 22 WestSamplewasfounddetachedfromthestructureandcol-lectedfromthegroundadjacent.Purplefinish(base).
JMH 23 East
Samplewasfounddetachedfromthestructureandcollectedfromtheground.Containsferrouswiremesh;thinsectiontakenadjacenttowire.Stereomicrographshowsthattheremaybeareddishbrownlayerunder-lyingthepurplepaint.Purplefinish(base).
Figure II.1. Petrographicsamples,alongwithnotesaboutthelocationandsamplefeatures.
sample.Themineralogyforthebrownandcoarsecoatsissimilar,butthespacingofthegrainsislarger
forthecoarsecoat.Intwocases,theembeddedwirewovenlathwasevidentinthinsection.3
Despitedespitetheharshclimatetowhichitisexposed,theweatheredcementisremarkably
wellpreserved.Thecementmatrixisstillwelladheredtotheaggregateinthefinishandbrown
coats,andthecarbonationdepthvaries(Figure II.2).Inonlyafewinstances,therewasevidenceof
microcrackswhicharelinedwitheithercarbonatedcementorcalcifiedfreelime(Figure II.3).While
saltsubflorescencehadbeenobservedincrosssection,nocrystalizedsaltwasfoundinthinsection
examination.Thecementmatrixwasmostlywelladheredtotheembeddedmetallicreinforcement.
Themetallicelementsshowsomeevidenceofferrouscorrosionincrosssectionandrustdepositswere
visibleinthinsection,butthisdoesnotappeartobeinducingphysicaldamagetothesurrounding
cement matrix (Figure II.4). The matrix surrounding micro-cracks on the exterior and posterior surfaces
ofsamplesweremorethoroughlycarbonatedthanthesurroundingmatrix.Thefinishcoatsare
composedofwhiteportlandcementwithmineralpigmentsadded,whichcolorthecementmatrix.
Theindividualmineralsweretoosmalltobeediscernedinthinsectionsofurtherchemicaltestingwill
requiredtoidentifythesecomponents.
3 JMH 12 and 15.
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Figure II.2 Samplesshowdifferingdepthsofcarbonation.JMH16(top)hascarbonatedcementmatrixextendingintothebrowncoat,whileJMH18(bottom)demonstrateslittlecarbonation.(XPL,50xmagnification)
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Figure II.3 Somemicrocrackingwasevidentinsomesamplesontheposteriorsurfaceofthecoarsecoat;inthesecasescarbonationwasaffectingboththeexteriorandinteriorfacesofthestucco.(JMH16,XPL,100xmagnification)
Figure II.4 Thecementmatrixsurroundingthemetalwire(opaque,centerofimage)appearstoonlyhaveminormicrocrakingandcarbonationofthecementmatrix.Norustdepositswereobserved.(JMH16,XPL,100xmagnification)
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iv.WaterAbsorption
ASTMC97/C97M-15,Standard Test Methods for Absorption and Bulk Specific Gravity of
Dimension Stone,isusefulforindicatingthedifferencesinabsorptionbetweenvariousstonematerials;
thevariabilityinstonecharacteristicsandqualityistypicallycontrolledbyusingasmanysamplesasare
necessaryfordetermininggaterangeofproperties.Forthecementstucco,thismeansusingmultiple
testsamplesinordertodetermineanaveragerateofabsorption.Duetothelimitationsofavailable
material,thedimensionsrecommendedinASTMC97/C97M-15werenotpossible.Instead,thesample
materialwasdividedinto0.75x0.75x0.75in.cubesusingaRIGID7in.tilesawwithacontinuous-rim
diamond blade.
ThesampleswereconditionedpriortotestingaccordingtoASTMC97/C97M-15;thesamples
beingdriedfor48hoursinaventilatedovenatatemperatureof140±4°F.Atonehourintervalsinthe
lastthreehours,thespecimenswereweighedtoensurestableweight.Priortosubmersion,thesamples
werecooledinaroomfor30minutesandthenweighed.Thesixteensamplesweredividedintotwo
groupsbasedonthewhetherplaneswereplane(GroupA)orintersectedvoids(GroupB) (Figure II.5).4
Followinginitialpreparation,thesamplesweresubmersedindistilledwaterat72±4°F(Figure II.6). The
sampleswerethenremovedfromthewaterbathatintervals,surfacedriedwithadampcloth,andeach
weighed.Theabsorptionforeachspecimenwascalculatedasfollows:
Absorption(weight%)=[(B-A)/A]x100
where:A=weightofthedriedspecimen,oz.,andB=weightofthespecimenafterimmersion,oz.
ThesevalueareplottedaccordingtotimeforeachsampleinFigure II.7.
Thepercentporosityiscalculatedasfollows:
%Porosity=(Vp /Va)X100
where:Vp=volumeofpores(cm³)
Va=volumeapparent(cm³).
These results are in Figure II.8.
Ultimately,bothGroupAandGroupBhadsimilarresults.Theaveragewaterabsorptionforall
sampleswasapproximately6%andtheaveragepercentporosityofthesamplesis12.98%±1.47%.This
figureissimilartoresultsforcommerciallyavailablebuildinglimestone(0.95to17%)andsandstone(1.9
to22%),suggestingthatthecementhasasimilarcapacitytoabsorbwaterasstonesdeemeddurablein
exposure.5
4Presumably,cubeswithplanesthatintersectexistingvoidscouldhaveamoreaccessibleporenetwork.5D.W.KesslerandW.H.Sligh,“PhysicalPropertiesofthePrincipalCommercialLimestonesUsedforBuildingCon-
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Figure II.5Samplesforwaterabsorptiontesting,devidedintoGroupsAandBbasedonthecharacteristicsofthesamplefaces.
Figure II.6 SampleGroupsAandBsubmersedinwater.
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0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0 50 100 150 200 250
Mass(g)
Time(Hours)
WaterAbsoprtion forJMHSamples
A1 A2 A3 A4 A5 A6 A7 A8
B1 B2 B3 B4 B5 B6 B7 B8
Figure II.7. WaterAbsorptionRateforSamples.TherateofabsoprtiondidnotdifferbetweenGroupA(yellow)andGroupB(blue).
Absorpti
on(%
ofo
rigina
lweigh
t)
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Test Sample No. M0 (g) Ms (g) Vp (cm3) Va (cm3) % Porosity
A1 13.99 14.88 0.89 7 12.71
A2 13.9 14.69 0.79 6 13.17
A3 13.78 14.58 0.8 6 13.33
A4 15.16 16.04 0.88 10 8.80
A5 14.74 15.66 0.92 8 11.50
A6 13.59 14.40 0.81 6 13.50
A7 13.86 14.68 0.82 6 13.67
A8 13.83 14.62 0.79 6 13.17
B1 13.51 14.38 0.87 6 14.50
B2 13.54 14.36 0.82 6 13.67
B3 13.33 14.16 0.83 6 13.83
B4 13.03 13.78 0.75 6 12.50
B5 12.03 12.73 0.7 6 11.67
B6 12.89 13.68 0.79 6 13.17
B7 14.59 15.52 0.93 6 15.50
B8 13.51 14.29 0.78 6 13.00
Figure II.8. PercentPorosityforWaterAbsorptionSamples.
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v.MechanicalTesting
ThemethodologyforthistestisbasedonASTMC580-02,Standard Test Method for Flexural
Strength and Modulus of Elasticity of Chemical-Resistant Mortars, Grouts, Monolithic Surfacings, and
Polymer Concretes,whichspecifiesdimensions,method,andcalculationsforevaluatingconcrete
mortars.However,becausethisspecificationisdesignedforsamplesthatareformedratherthancut,
referencetoASTMC99M15,Standard Test Method for Modulus of Rupture of Dimension Stone, is useful
in that it dictates that dictates the faces of each sample should be as near to plane as possible, and
roughmaterialsmaybegroundtoasmoothfinishtoavoidpointloading.6
Thesampleswerecutintothirteenrectangularprismsmeasuring6.0in.x1.0in.x11/16in.±
1/32in.Eachsamplecontainedwiremesh,asdemonstratedincrosssectionandonesamplehadanail
headandfurringdevice.7Eachsamplereceivedforcetangentialtothedirectionofthewiremeshand
thestuccolayers.Anareaofonesquareinchwasleveledinthemiddleofthefinishedsurfaceforeach
samplebypassingthesamplebackandforthunderthesamecontinuousrimdiamondblade(Figure
II.9).8Thethicknessforthesamplepopulationwas0.67±0.07in.,basedononemeasurementtakenat
thecenteroftheleveledareaforeachsamplebeforetesting.
AnInstron4206testingmachineattheLaboratoryforResearchontheStructureofMatter
(LRSM)wasusedforthreepointbendingtests.Specimenswereplacedflatwiseonsupportblocks,
spacedtoa4in.span.Thesupportswerethenadjustedtoensurethatlengthofthecenterloading
nosewasflushtothesurfaceofthesample(Figure II.10).Forcewasapplieduntilthesamplebroke.The
flexuralstrengthofthematerialisequaltothestresscalculatedatmaximumload,where
S=3FL/2bd²
where:
S = Stress in the specimen at midspan, psi
F = the maximum load at or prior to the moment of crack or break, lbf
L = span, in.
b=widthofthebeamtested,in.,and
d = depth of the beam tested, in.
structionintheUnitedStates.,”TechnologicalPapersoftheBureauofStandards(Washington:GovernmentPrintingOffice,1927),519-520.6ASTMC580-02alsorecommendsthattheundersideofthesamplesaregroundtoplanetoensurethatthesam-pleislevelwhenplacedonthetestingsupports.Thiswasnotappliedbecausethebottomofsampleswerenearlyplane,andexcessivegrindingcouldpotentiallyintroducemicrocrackstothesample.7 TheshankhadbeenremovedbeforeshipmenttoPhiladelphiabyNPSstaff.8VariancefromASTMC580-02;grindingtheentiresurfacewasdeterminedtonotbedesirableasthemechanicalactionandvibrationscouldhaveintroducedmicrocrackstothestructureofthefabric,artificiallyreducingthestrength of the material.
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Figure II.9. Thethirteenstuccoprismspreparedforthreepointbending;oneinchsquarewaslevelledinthecentertopreventpointloading.(Photobyauthor,2018)
Figure II.10 Stress-StrainCurvesderivedfromthreepointbendingdata.(Photobyauthor,2018)
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0
50
100
150
200
250
0 10 20 30 40 50 60 70 80 90 100
Stress(psi)
ThreePointBendingResults
Figure II.11 Stress-StrainCurvesderivedfromthreepointbendingdata.
Withacoupleofexceptions,thebehavioroffailureconformedtoexpectationsforbrittle
materials (Figure II.11).TheModulusofRuptureforsamplestestedvariedwidely;theaveragevaluewas
1493.96psiwithastandarddeviationof376.83psi (Figure II.12).Thisfigureissimilartothelowerrange
obtained for architectural limestone and sandstone. The thickness of the sample had no discernible
correlationtoitsmodulusofrupture;itispossiblethattheadhesionofthecementmatrixtothewire
clothwithinthesamplecontributestostrengthofthematerialinbending.9
9ConversationwithDr.AlexRadin,oftheLaboratoryforResearchontheStructureofMatter.
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Test Sample No. Breaking Load (lbs) Prism Dimensions Modulus of Rupture (psi)
MT 1 N/A** 6 in. x 1 in. x 0.60 in. N/A
MT 2 119.35 6 in. x 1 in. x 0.70 in. 1478.27
MT 3 101.31 6 in. x 1 in. x 0.72 in. 1189.03
MT 4 82.03 6in.x1in.x0.69in. 1036.78
MT 5 149.04 6in.x1in.x0.68in. 1919.78
MT 6 116.38 6 in. x 1 in. x 0.61 in. 1849.21
MT 7 126.18 6 in. x 1 in. x 0.60 in. 2078.68
MT8 146.65 6 in. x 1 in. x 0.71 in. 1733.26
MT9 78.89 6 in. x 1 in. x 0.70 in. 955.05
MT 10 104.51 6 in. x 1 in. x 0.71 in. 1254.50
MT 11 80.96 6 in. x 1 in. x 0.66 in. 1111.78
MT 12 138.95 6 in. x 1 in. x 0.70 in. 1703.86
MT 13 122.09 6 in. x 1 in. x 0.67 in. 1617.34
**MT1wassubjectedtoaseriesofpreliminaryteststocalibratethesettingsfortheInstron.Theresultswereabnormallylowlikelyduetofatigueimposedbyrepeatedforceappliedtothesampleinthesepreliminarytrials.
Figure II.12. BreakingLoadandModulusofRuptureformechanicaltestingsamples.
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vi.SaltTesting
Saltefflorescencewasnotvisibleonthestructureduringfieldinvestigation,however
photomicrographsofcrosssectionsrevealedlargewhitemineralsbetweenthebrowncoatandfinish
layer in a number of instances (Figure II.13).Forsalttesting,asamplewassubmergedindeionizedwater
andthenthesolutionwastestedtodeterminethepresenceofsaltionsinthesolution.Nitrite,chloride,
andsulfateteststripswereusedbecausethepotentialsourceofthesaltwasunknown.Asmallsample
wasdetachedfromJMH17withahammerandchisel.Thesamplefragmentwasgroundtoapowder
withamortarandpestletoensurethatanysaltcontentinasamplewouldbedissolvedinthewater.10
Thepowderedsamplewasaddedtoaglassbeakerwith50mldeionizedwater,andagitatedwitha
magneticstirringhotplateforfiveminutes(Figure II.14).Oncetheportionofpowderappearedtobe
dissolvedinthewater,thestripsweredippedintothesolutionandthenlefttodry.Thestripsindicate
thatthesamplecontainsmoderateamountsofnitrites(25to50mg/L)andsulfates(1500mg/L)(Figure
II.15).
Thepresenceofsaltisworrisome,astherepeatedcrystallizationanddissolutioninthepores
can cause cracking and spalling of the surfaces.11 To approximate the risk that these materials pose in
thecement,itisessentialtodeterminewhetherthesaltcontentislikelytoincreaseorremainthesame.
Thesulfateoriginateseitherfromexternalorinternalsources.Soilsurveysintheareaindicatethat
thereisalowlikelihoodthatcomponentswithinthesoilmaycontributetoelectrochemicalandphysical
deteriorationofconcrete;thesearebasedonevaluationsofsulfateandsodiumcontentandacidity
of the soil.12Theprimaryinternalsourceforsulfateisahighcontentofgypsumincludedintheinitial
portlandcementmixturetodeterearlyset.Asecondpossibilityisthemineralcontentofthewaterused
tomixtheconcrete,likelyfromtheKellyWarmSpringviatheMormonDitch.Furthertestingisrequired
toidentifythesourceofthesulfate.
10Itispreferabletogrindthesampletoapowderratherthansubmergeasolidvolumewithdisconnectedpores.11DavidOdgers,ed.,Concrete,vol.8,PracticalBuildingConservation(London:EnglishHeritage,2012),97.12WebSoilSurvey,https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx.
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Figure II.13PhotomicrographofJMH17revealswhitesubstanceattheinterfaceofthebrowncoatandfinishcoat.Magnification100x(PhotobyM.-C.Boileau,2018)
Figure II.14Thepowderedfractionwascombinedwithdeionizedwaterusingamagnet-icstirrerhotplate(Photobytheauthor,2018).
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Figure II.15 Test strips indicate that the sample contains both sulfates (top)andnitrates(below).(Photobytheauthor,2018)
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JMH 12 taken from the base of the north ele-vationneartheeastcorner.Photobyauthor,2017.
JMH 16 taken from base of the south elevationneareastcorner.Photobyauthor,2017.
JMH17takenfrombaseoftheeastelevationnear the south corner. Photo by author, 2017.
JMH3takenfromdisplacedcrack(+)belowleftcornerofeastwindowonsouthelevation. Characterizationofstuccofromanexposedareawhichshoulddemonstrateconditionofcementwitheposuretoweatherandthermalcycling. Photo by author, 2017.
Appendix III: STUCCO SAMPLES
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JMH 20 taken from corner of north and east el-evationundertheeave.Photobyauthor,2017.
The bulk sample has poor interlayer adhesion, perhapsduetofaultyapplication/installation.Sample taken to characterize unexposed ce-ment matrix.
JMH22wasfounddetachedfromthestructure and collected from the ground adjacenttothesouthwestcornerofthewestLaddition.SampletakeninJuly2017by J. Hinchman. Photo by author, 2017.
JMH23wasfounddetachedfromthestruc-ture and collected from the ground adjacent to thesouthcorneroftheeastelevation.Sampletaken in July 2017 by J. Hinchman. Photo by author, 2017.
JMH18takenfromthenorthwestcorneroftheLaddition.Photobyauthor,2017. Sampleiscurvedandhasathickerfinishcoatpaintlayer,likelytheresultofapplication.
Appendix III: STUCCO SAMPLES
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Smp
No.
Loca
tion
Des
crip
tion
Elev
ation
(s)
Pain
t col
orTe
sting
Dat
e Co
llect
edCo
llect
ed b
y
JMH
03
Belowleftcorne
rofeastw
indo
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Sout
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trog
raph
icExaminati
on10
/21/20
18J.
Hin
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an,
S.Stratt
e
JMH
12
Base
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rse
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co fr
om c
orne
r.North
Purp
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trog
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on10
/21/20
18J.
Hin
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S.Stratt
e
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16
Base
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uth
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icExaminati
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17
Base
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stuc
co fr
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eter
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t-ed
areaatSEcorner.
East
Purp
lePe
trog
raph
icExaminati
on,
SaltTesting
10/21/20
18J.
Hin
chm
an,
S.Stratt
e
JMH18
NWcorne
rofth
eell.
North,W
est
Pink
Petrog
raph
icExaminati
on10
/21/20
18J.
Hin
chm
an,
S.Stratt
e
JMH
20
NEcorner,u
ndereave.
East,N
orth
Pink
Petrog
raph
icExaminati
on10
/22/20
17J.
Hin
chm
an,
S.Stratt
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JMH
22
SWcorne
rofth
eell.
West
Purp
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trog
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icExaminati
onSu
mm
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017
J. H
inch
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JMH
23
Base
cou
rse
stuc
co fr
om d
eter
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t-ed
areaatSEcorner.
East
Purp
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trog
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icExaminati
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WaterAbsorpti
onSu
mm
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017
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inch
man
JMH
24
Areaofsignifican
tlossatbaseof
southelevati
on.
Sout
hPi
nkTh
ree
poin
t ben
ding
Spring
201
8B.Guild
(GRT
E)
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Re
ctif
ied
ph
oto
of e
ast
ele
vatio
n.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Re
ctif
ied
ph
oto
of s
ou
th e
leva
tion
.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Re
ctif
ied
ph
oto
of w
est
ele
vatio
n.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Re
ctif
ied
ph
oto
of n
ort
h e
leva
tion
.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Condition: Crack Sizes Small
Extra-Small Extra-Large
LossLarge
Medium
Windows obscured by plywood
SCALE IN FEET
0 5 101
Cra
ck
co
nd
itio
ns
on
ea
st e
leva
tion
.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Condition: Crack Sizes Small
Extra-Small Extra-Large
LossLarge
Medium
Windows obscured by plywood SCALE IN FEET
0 5 101
Cra
ck
co
nd
itio
ns
on
so
uth
ele
vatio
n.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Condition: Crack Sizes Small
Extra-Small Extra-Large
LossLarge
Medium
Windows obscured by plywood
SCALE IN FEET
0 5 101
Cra
ck
co
nd
itio
ns
on
we
st e
leva
tion
.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
SCALE IN FEET
0 5 101
SCALE IN FEET1/4” = 1’-0”
0 1 5 10
Condition: Crack Sizes Small
Extra-Small Extra-Large
LossLarge
Medium
Windows obscured by plywood
SCALE IN FEET
0 5 101
Cra
ck
co
nd
itio
ns
on
no
rth
ele
vatio
n.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
10 5 10
SCALE IN FEET1/8” = 1’-0”
Sam
ple
loc
atio
ns
for e
ac
h e
leva
tion
.
Petrographic Analysis
Paint Analysis
MechanicalTesting Paint analysis will be part of a succeeding
report to be completed in the fall of 2018.
Hollow markers indicate samples that come from the junction of two elevations.
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
Sam
ple
loc
atio
ns
for n
ort
h e
leva
tion
.
22
18
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
Sam
ple
loc
atio
ns
for s
ou
th e
leva
tion
.
03
16
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
Sam
ple
loc
atio
ns
for e
ast
ele
vatio
n.
20
17
23
JOHN
MO
ULTO
N H
OM
ESTE
AD
1304
0 A
nte
lop
e F
lats
Ro
ad
G
ran
d T
eto
n N
atio
na
l Pa
rk, M
oo
se, W
yom
ing
DES
CR
IPTI
ON
SHEE
T ID
ENTI
FIC
ATI
ON
:
Sam
ple
loc
atio
ns
for n
ort
h e
leva
tion
.
20
12
08