ADDRESS: 3948-50 WALNUT ST Proposal: Apply terra cotta sealant Type of Review Requested: Final Approval Owner: City of Philadelphia Applicant: Glenn Kucher, Robert Michaels and Associates, Inc. History: 1905, Clarence C. Zantzinger, architect, West Philadelphia Branch of the Free Library Individual Designation: 4/10/2015 District Designation: None Staff Contact: Megan Cross Schmitt, megan.schmitt@phila.gov, 215-686-7660

BACKGROUND: This Renaissance Revival style building was constructed in 1905 to the design of Clarence C. Zantzinger. The building, the first Carnegie Library branch built in Philadelphia, has a granite base and is clad with glazed terra cotta tiles. There is a modern bay window at the north façade.

SCOPE OF WORK: The following work is limited to the building’s west façade:

Power wash water table, coping stones and terra cotta elements; At the water table - cut out mortar joints and replace with new backer rod and sealant; At the coping stones - cut out sealant and backer rod and replace in kind; At the terra cotta façade – cut out mortar joints and install new tooled mortar joints; At the windows – remove sealant and backer rod from around the windows and masonry

openings and replace in kind; Reglaze terra cotta façade from the top of the window lintels to the top of the parapet

walls.

STANDARDS FOR REVIEW:

The Secretary of the Interior’s Standards for the Treatment of Historic Properties and Guidelines include:

Standard 7: Chemical or physical treatments, if appropriate, will be undertaken using the gentlest means possible. Treatments that cause damages to historic materials will not be used.

o The proposal indicates that the façade will be power washed without specifying water pressure or whether any cleaning products will be used;

o The proposal to treat areas of the terra cotta where the glazing has been lost is intended to address what has been described as a problem with water infiltration. The waterproofing work, including the removal and replacement of mortar and sealant at the joints is understood to be in response to the same issue. However, the application materials do not provide sufficient information about the existing conditions at the roof in order to understand whether water is leaking from there into the building and causing the loss of glazing seen at locations under the projecting cornice. The staff has concerns that the proposed treatment is not adequately addressing the root cause of the water infiltration because there is not sufficient evidence provided in the application that explains specifically why or where it is occurring.

o The staff does not understand if the proposed coating is intended to both repair/fill existing voids/spalls and perform as a waterproof replacement for the missing glaze.

o The staff would like to know what percentage of the terra cotta tiles are experiencing this loss of glaze? Is this loss limited to the west façade of the building? How will the coated tiles look next to those that remain uncoated? Is the water infiltration limited to the west façade of the building?

STAFF RECOMMENDATION: The staff requests assistance from the members of the Architectural Committee to determine whether the application adequately explains the water infiltration issue, and if the proposed scope of work is the appropriate manner in which to address the problem.

Figure 1. Aerial image of 3948-50 Street as viewed from the south. Cyclomedia, 2019.

Figure 2. Western façade of 3948-50 Street as viewed from the south. Cyclomedia, 2018.

WHERE TO USE Replicate glaze on terracotta or fire skin

on brick. Apply over Terra-Color to match surrounding undamaged terracotta.

Terracotta Finish

DIVISION 4 TERRACOTTA FINISH

Brush or roller applied, single component, water based clear sealer. Available in gloss and matte finish.

Performance Characteristics Durable

■ Advanced chemistry provides long lasting protection from weathering. UV stable

■ Will not yellow ■ or discolor with age.

Anti-carbonation ■ Mitigates carbonation

of concrete. Breathability

■ Water vapor permeable. Water repellent

■ Passes ASTM E514. Environmentally friendly

■ Water based technology, low odor, non-flammable. Two finishes

■ Gloss and Matte.

Surface Preparation■ Remove loose and deteriorated

material, laitance, dirt, dust, oil and any surface contaminants that will inhibit proper adhesion.

■ If acid washing is used to prepare substrate, neutralize with 1 part ammonia to 3 parts water solution flooded over the surface. Residual acid in the substrate will cause Terracotta Finish to form a milky film instead of a clear finish. If this occurs, the material must be removed.

■ Surface must be dry at time of application to allow maximum penetration.

■ Protect adjacent areas from overspray.

Priming ■ Priming is not necessary

under normal circumstances. Mixing ■ Stir container.

Application ■ Always apply a test area to

determine suitability of application. ■ Brush or roll material onto

substrate in a uniform 6 mils. coat. ■ Brush out ponded material

before surrounding area dries. ■ 2 coats are recommended

for complete protection. ■ Allow the first coat to cure

3 - 4 hours @ 72°F; 7 - 8 hours @ 50 - 70°F before applying additional coats.

■ Each additional coat of Terracotta Gloss Finish will increase the intensity of gloss.

Curing ■ Protect from moisture for 24

hours @ 72oF.

Clean Up ■ Clean tools, equipment and

adjacent areas with water before material dries.

Coverage/Yield ■ Actual coverage will vary

depending on substrate porosity. Test application should be applied to determine actual coverage, number of applications required and compatibility with substrate. Typical coverage

■ Terracotta – 200 - 300 ft.2/gal. MIMIC/Matrix – 150 - 250 ft.2/gal. Brick – 200 - 300 ft.2/gal. Concrete block – 75 - 125 ft.2/gal.

Product Handling

Packaging ■ 1 gallon container.

Shelf Life ■ 18 months in unopened containers.

Storage ■ Protect from freezing. ■ Transport and store in cool,

clean, dry conditions in unopened containers.

■ High temperature will reduce shelf life.

Limitations■ If acid washing is used to clean,

substrate must be neutralized with 1 : 3 ammonia/water solution flooded over the surface.

■ Do not apply if precipitation is forecast within 24 hours of application.

■ Do not apply in strong winds. ■ Do not apply to frozen surfaces. ■ Do not apply if temperature

of substrate is below 45°F. ■ Do not apply if ambient

temperature is below 45°F. ■ Do not apply in areas

susceptible to water ponding. Health and Safety ■ Product is alkaline. ■ Do not ingest. ■ Avoid breathing dust. ■ Avoid contact with skin and eyes. ■ Refer to Safety Data Sheet (SDS) for

additional information.

First Aid ■ In case of skin contact, wash

thoroughly with soap and water. ■ For eye contact, flush with a high

volume of water for at least 15 minutes and contact a medical professional.

■ For respiratory problems, remove person to fresh air.

■ If respiratory difficulty persists, contact a medical professional.

Disposal ■ Dispose of material

in accordance with local, state or federal regulations.

Technical Data

Physical state and appearance Wet Dry

Thick – milky white liquid Clear – dull or gloss – plastic-like film

Base Aqueous

Polymer Carboxylated styrene acrylic

pH >9.5

Percent solids by weight 53%

Flash point ASTM D56 150oF Seta cc

Volatile organic content - VOC ASTM D3960 58 gms./liter

Density of liquid coatings ASTM D1475 8.0 lbs./gal.

Water vapor transmission ASTM D1653 wet cup 11 perms – 1 coat

Accelerated weathering – QUV

ASTM G154

2000 hours – UV-B cycled with condensation – no effect

Water penetration and leakage ASTM E514 100% reduction

Freeze/thaw stability ASTM C932 Pass – 5 cycles @ 15oF

Heat stability ASTM C932 Pass – 4 weeks @ 120oF Gloss finish – terracotta tile

ASTM D523

85oF untreated 1.5 – treated 11.0 60oF untreated 1.5 – treated 11.0

FOR PROFESSIONAL USE ONLYConproco warrants this product for one year from the date of manufacture to be free from manufacturing defects and to meet the technical properties on the current technical data sheet if used as directed within shelf life. User determines suitability of product for use and assumes all risks. Buyer's sole remedy shall be limited to the

purchase price or replacement of product, exclusive of labor or cost of labor. January 8, 2016

NO OTHER WARRANTIES EXPRESSED OR IMPLIED SHALL APPLY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. CONPROCO CORP SHALL NOT BE LIABLE UPON ANY LEGAL THEORY FOR SPECIAL OR CONSEQUENTIAL DAMAGES.

17 PRODUCTION DRIVE, DOVER, NH 03820 TELEPHONE 800.258.3500 • FAX 603.743.5744 • WEB ADDRESS www.conproco.com

Terracotta Finish

Technical Data Sheet

DOWSIL™ 791 Silicone Weatherproofing Sealant

UNRESTRICTED – May be shared with anyone ®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of DowDOWSIL™ 791 Silicone Weatherproofing Sealant

Page 1 of 4 © 2018 The Dow Chemical Company. All rights reserved. Form No. 63-6149-01 C

Neutral, one-part silicone sealant

Features & Benefits

Ideal for expansion, connection, perimeter and other movement joints Neutral cure – suitable for use on coated glass, galvanized steel, masonry and other porous and non-porous substratesExtension/compression movement capability of up to ±50 percent of the original joint widthExcellent weatherability, virtually unaffected by sunlight, rain, snow, ozone Excellent unprimed adhesion to a wide variety of construction materials and building components Ease of application – ready to use as supplied Excellent rheology, low string upon gunning

Composition One-part, neutral-cure, RTV silicone sealant

Applications DOWSIL™ 791 Silicone Weatherproofing Sealant is a specified, premium performance weather sealing product specifically designed for general glazing and weather sealing in curtain wall and building facades.

Typical Properties Specification Writers: These values are not intended for use in preparing specifications.

Test1 Property Unit Result

Uncured – As Tested at 50% RH and 23°C (73°F)

ASTM C639 Flow (Sag or Slump) inches (mm) 0

ASTM C1183 Extrusion Rate g/minute 210

Working Time minutes 20

ASTM C679 Tack-free Time, 77°F, 50% RH minutes 45

Curing Time at 77°F (25°C) and 50% RH days 7–14

VOC Content2 g/L 45

Application Temperature °C 4 to 40

1. ASTM – American Society for Testing and Materials.2. Based on South Coast Air Quality Management District of California. Maximum VOC is listed both inclusive and

exclusive of water and exempt compounds.

UNRESTRICTED – May be shared with anyone ®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of DowDOWSIL™ 791 Silicone Weatherproofing Sealant

Page 2 of 4 © 2018 The Dow Chemical Company. All rights reserved. Form No. 63-6149-01 C

Typical Properties (Cont.)

Test Property Unit Result

Specific Gravity 1.51

As Cured – After 21 days at 50% RH and 25°C (77°F)

ASTM C661 Durometer Hardness, Shore A points 25–30

ASTM C794 Peel Strength lb/in(kg/cm)

30(5.4)

ASTM D624 Tear Strength Die B KN/m 9.0

ASTM C719 Joint Movement Capability % ±50

Service Temperature °C -50 to 150

ASTM C1135 Tensile Adhesion Strength:

At 100% Extension Psi(MPa)

58(0.40)

Elongation at Break % 430

Ultimate Tensile Strength Psi(MPa)

120(0.83)

Description DOWSIL 791 Silicone Weatherproofing Sealant is a one-part, non-sag neutral- cure sealant which easily extrudes and cures at ambient temperature by reaction with moisture in the air to form a durable, flexible silicone rubber seal.

How To Use Joint PreparationClean all joints removing all foreign matter and contaminants such as grease, oil, dust, water, frost, surface dirt, old sealants or glazing compounds and protective coatings.

Application MethodInstall backing material or joint filler, setting blocks, spacer shims and tapes. Mask areas adjacent to joints to ensure neat sealant lines. Primer is generally not required on non-porous surfaces, but maybe necessary for optimal sealant of certain porous surfaces. A test placement is always recommended. Apply DOWSIL 791 Silicone Weatherproofing Sealant in a continuous operation using a positive pressure. (The sealant can be applied usingmany types of air-operated guns and most types of bulk dispensing equipment. Before a skin forms (typically within 15 minutes), tool the sealant with light pressure to spread the sealant against backing material and the joint surfaces. Remove masking tape as soon as the bead is tooled.

UNRESTRICTED – May be shared with anyone ®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of DowDOWSIL™ 791 Silicone Weatherproofing Sealant

Page 3 of 4 © 2018 The Dow Chemical Company. All rights reserved. Form No. 63-6149-01 C

Approvals/Specifications

Meets the requirements of:

ASTM C920 Type S, Grade NS, Class 50, Use NT, M, G, A ISO11600 F&G-25LMJC/T882-2001 I 25LM GB/T14683-2003 B G, F 25LMKS F4910-2010 F-25LM EN15651-1/2:2012

Colors This product is available in 8 colors: black, grey, dark gray, metal gray, bronze, limestone, precast white and white. Custom colors may be ordered to match virtually any substrate.

Handling Precautions

PRODUCT SAFETY INFORMATION REQUIRED FOR SAFE USE IS NOT INCLUDED IN THIS DOCUMENT. BEFORE HANDLING, READ PRODUCT AND SAFETY DATA SHEETS AND CONTAINER LABELS FOR SAFE USE, PHYSICAL AND HEALTH HAZARD INFORMATION. THE SAFETY DATA SHEET IS AVAILABLE ON THE DOW WEBSITE AT CONSUMER.DOW.COM, OR FROM YOUR DOW SALES APPLICATION ENGINEER, OR DISTRIBUTOR, OR BY CALLING DOW CUSTOMER SERVICE.

Usable Life andStorage

When stored at or below 30°C (86°F) in the original unopened containers, DOWSIL 791 Silicone Weatherproofing Sealant has a usable life of 12 months from the date of manufacture. Refer to product packaging for “Use By” date.

Packaging Information

DOWSIL 791 Silicone Weatherproofing Sealant is available in 300 ml disposable plastic cartridges that fit ordinary caulking guns, and 500 ml sausages.

Limitations DOWSIL 791 Silicone Weather-proofing Sealant is not approved for use as a structural sealant.

DOWSIL 791 Silicone Weather-proofing Sealant should not be used:

In below-grade applicationsWhen surface temperatures exceed 50°C (122°F)On surfaces that are continuously immersed in waterOn building materials that bleed oils, plasticizers or solvents, green or partially vulcanized rubber gaskets or tapes

SGBP 2017-1253

Page 4 of 4 ®Trademark of The Dow Chemical Company Form No. 63-6149-01 C

Limitations (Cont.) On frost-laden or wet surfaces In totally confined joints (the sealant requires atmospheric moisture for cure)If the sealant is intended to be painted (paints do not typically adhere to most silicone sealants)To surfaces in direct contact with food or other food-grade applicationsNatural stone unless substrate been approved or passed by ASTM C1248 non-stain test evaluation.

This product is neither tested nor represented as suitable for medical or pharmaceutical uses.

Health And Environmental Information

To support customers in their product safety needs, Dow has an extensive Product Stewardship organization and a team of product safety and regulatory compliance specialists available in each area.

For further information, please see our website, consumer.dow.com or consult your local Dow representative.

consumer.dow.com LIMITED WARRANTY INFORMATION – PLEASE READ CAREFULLY The information contained herein is offered in good faith and is believed to be accurate. However, because conditions and methods of use of our products are beyond our control, this information should not be used in substitution for customer’s tests to ensure that our products are safe, effective, and fully satisfactory for the intended end use. Suggestions of use shall not be taken as inducements to infringe any patent.

Dow’s sole warranty is that our products will meet the sales specifications in effect at the time of shipment.

Your exclusive remedy for breach of such warranty is limited to refund of purchase price or replacement of any product shown to be other than as warranted.

TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, DOW SPECIFICALLY DISCLAIMS ANY OTHER EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY.

DOW DISCLAIMS LIABILITY FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.