Upload
phamhuong
View
215
Download
1
Embed Size (px)
Citation preview
Durable Building Envelope
January 14, 2005
11:00 – 12:00 PM
Glen SalasD&R [email protected]
(301) 588-9387
Dana BresHUD, PD&R
[email protected](202) 708-4370 x5919
IBS 2006
2Partnership for Advancing Technology in Housing
About the PATH Program
Partners: Advancing Technology in HousingU.S. Department of Housing and Urban DevelopmentBuilders and RemodelersHomeownersEducators, Researchers, and InsurersManufacturers, Designers, DistributorsTackling institutional barriers to innovationPromoting focused co-operative housing research Providing the latest information on innovative building materials, processes, and systems
3Partnership for Advancing Technology in Housing
The PATH Tech Sets
Resource Efficient
Plumbing
Forced Air System
Durable Building Envelope
Energy Efficient Lighting
Storm Resistant Roofing
4Partnership for Advancing Technology in Housing
Overview
1. What are Tech Sets2. Tech Set #2 - The Durable Building
Envelope3. Tech Set #5 – Storm Resistant Roofing4. Questions and Discussion
5Partnership for Advancing Technology in Housing
PATH TECH SETS Goals for Housing Improvement:
AffordableDurable
Safe to build and live inDisaster resistant.Longer intervals between maintenance work.
Energy EfficientEnvironmental Performance
Air quality and occupant comfortReduced use of natural resources
6Partnership for Advancing Technology in Housing
Why TECH SETS?
Integration of several technologies promotes a systems design approach
Benefits enhanced when certain technologies are used together
Tech Sets answer the what, how, so what, and who cares of technology deployment
Facilitates acceptance of the features rather than fear of the new product or process
8Partnership for Advancing Technology in Housing
Start with Good Design Details
Site house to benefit from passive solar exposure for winter warming and prevailing breezes for summer cooling Overhangs should be sized to provide summer shading Cover door openings with roofs and porchesDetail building and material interfaces with redundant barriers
9Partnership for Advancing Technology in Housing
Start with Design
Take advantage of the sun(and keep the rain off your walls and windows)
11Partnership for Advancing Technology in Housing
What? Precast Concrete Foundation
Foundation is installed on 6” compacted bank-run gravel base
Sub-base continuity beneath slab and wall eliminates need for interior drain tile
Foundation installed by the manufacturer.
Walls cure in plant; foundation can be backfilled as soon as it is braced by basement slab and floor deck.
12Partnership for Advancing Technology in Housing
What? Precast Concrete Foundation
Foundation is installed by the manufacturer.
Manufactured under quality-controlled factory conditions, and ready in a fraction of the time needed for a poured foundation
13Partnership for Advancing Technology in Housing
Courtesy: Superior Walls
What? Precast Concrete Foundation
14Partnership for Advancing Technology in Housing
How? Precast Concrete Foundation
Bond beam at bottom of wall disperses load –eliminating footingEngineered bond beams and greater cement/water ratio in mix provides strengthExtruded polystyrene foam (XPS) is cast in wall –X-1 wall will meet IRC Energy Efficiencyprovisions through Climate Zone 13 Vertical bond beams provide cavity for additional insulation/mechanicals, pre-drilled wire chases, and drywall attachment surface for simplified interior finishing
15Partnership for Advancing Technology in Housing
Precast Concrete Foundation So What?
Resource efficient - precast wall uses less concrete and more insulation than CMU or poured-in-place concrete
Controlled factory environment eliminates variation in mix or conditions that can be found in the field – no cold joints, form tie voids, or grout joints to allow moisture seepage
Site safety is enhancedExcavation is open for a shorter period Walls are set with a crane - fewer workers required in the excavation
16Partnership for Advancing Technology in Housing
Precast Concrete Foundation Who Cares?
IRC recognizes “approved” precastassemblies on gravel baseLocal approval on case-by-case basisFoundation plans can be certified by the manufacturer’s engineerCustomized product - Brickledges and porch haunches, openings for doors, windows, stairs and beam pockets must be specified at order placement
17Partnership for Advancing Technology in Housing
What? Redundant Barriers
Redundant BarriersUse building wrap or “weather resistant barrier” (WRB)Use mechanical flashings at all openings and plane abutments
Counter flashingHead flashingTrims and windows with integral “J”
Air seal inside and outCovered (roofed) door openings
18Partnership for Advancing Technology in Housing
How? Redundant Barriers
Sill seal at platform irregularities; air seal platform junctionsInstall housewrap or weather resistant barrier (WRB) over wall sheathing from bottom up, overlapped and tapedFlashings at windows, doors, corners, and building/material interfaces“J” trim provides drainage channel at junction of dissimilar cladding materialsProtect roof eave and overhang edges from ice dams and wind-driven rain with an adhesive membrane and drip edge trim
19Partnership for Advancing Technology in Housing
What? Advanced Framing Techniques
Minimize structural members without compromising load bearing capacity of the structureAlso referred to as Optimum Value Engineering - OVE
20Partnership for Advancing Technology in Housing
How? Advanced Framing Techniques
Design for modular layout 2’ modulesDoor and window openings at (24”) spacing distances from corners, each other
Install exterior wall studs on 24”center spacing.Install floor and roof components on 24” center spacing.
21Partnership for Advancing Technology in Housing
How? Advanced Framing Techniques
Right size headers by (wood) species and load, orInstall insulated or boxed headers on exterior bearing wallsEliminate headers at non-bearing openings.Install wood interior walls on 24”center spacing with single top plates.Ladder frame at perpendicular wall intersectionsMinimize wood in outside cornersDevelop framing plans to accompany architecturals and bill of materials so material is properly used. Order components and precuts where cost effective
22Partnership for Advancing Technology in Housing
Advanced Framing TechniquesSo What?
Good design and implementation can save 3-5% in framing package cost and streamline labor inputsEliminating redundant structural materials on exterior surfaces also eliminates thermal bridges and provides greater surface area for insulationEliminating excess material saves natural resourcesWider floor spacing provides larger bays for mechanical system layoutEfficient take-off and use means less waste and lower disposal fees
23Partnership for Advancing Technology in Housing
Tin Can Siding
Rubber Tire Building Envelope
Building EnvelopeSure, there are alternatives….
Check PATHnet for the details
24Partnership for Advancing Technology in Housing
Tech Set #3HVAC: Forced Air System
To decrease the cost of construction, maintenance and energy efficiency of housing by promoting effective systems integration of the conditioned air delivery network into the structural framework.
25Partnership for Advancing Technology in Housing
Energy-Efficient LightingA Personal Favorite: Tubular skylights
AKA – Solar Tubes
26Partnership for Advancing Technology in Housing
Storm Resistant Roofing1) Moderately pitched (4/12 to 6/12) hips rather than gables2) Baffled ridge and soffit vents minimize the number of roof penetrations3) Fascia Board extended below underside of soffit4) Grid-marked sheathing5) OVE structural members
6) Light-colored wind and impact resistant roof shingles7) Tape OSB seams with a self-adhering bitumen tape
8) Proper underlayment9) Valley, junction, and pipe penetration flashing
10) Proper fastener/nailing schedules11) Hurricane straps tied to load bearing components
27Partnership for Advancing Technology in Housing
Storm Resistant Roofing
Basis:The roof should act like a good umbrella
The worst of the weather stays beyond the drip line Does not fold when the wind gusts.
These recommendations will improve:Durability of the roof and building envelopeOccupant safety and disaster mitigationAffordability
28Partnership for Advancing Technology in Housing
What? Moderately pitched hips
Hips rather than gablesModerately pitched - 4/12 to 6/12 in areas where high winds are likely.
Flatter roofs withstand strong winds better than steep roofs.
29Partnership for Advancing Technology in Housing
What? Baffled ridge and soffit vents
Minimize the number of roof penetrationsBaffled ridge vents are preferred : they prevent airflow and wind driven rain from entering the attic through the ridge vent.
If added daylighting is desired, specify tubular skylights with polycarbonate domes.
31Partnership for Advancing Technology in Housing
What? Extended Fascia Boards
Minimize the number of roof penetrationsBaffled ridge vents are preferred : they prevent airflow and wind driven rain from entering the attic through the ridge vent.
If added daylighting is desired, specify tubular skylights with polycarbonate domes.
32Partnership for Advancing Technology in Housing
What? Grid-Marked Sheathing
4’x 8’ sheets installed like any other roof sheathingPerpendicular to the framing componentsGappedsupported with “H” clips at mid-span between trussesspaced at 24” on center
Grid marks facilitate cutting the sheets, using the correct fastening schedule, and the layout of shingle underlayment.
33Partnership for Advancing Technology in Housing
What? OVE Structural Members
Roof truss components and engineered wood girdersEngineered structural components save lumber resources because
typically spaced on 24” centerfabricated with small dimension lumber – 2x4 and 2x6
Shape usually more conducive than solid sawn lumber rafters to accept continuous insulation for building envelope energy efficiency .
34Partnership for Advancing Technology in Housing
What? The Right Roofing
Light-colored wind and impact resistant shinglesConsider the solar reflectance of the roof cladding and select light colors n warm climates
The higher the reflectance factor, the less heat absorbed by theroof from the sun. Cladding products that carry ENERGY STAR® reflectance ratings can be researched at the website for reflective roof products.
35Partnership for Advancing Technology in Housing
What? Proper Underlayment
Tape OSB seams with a self-adhering bitumen tape
Roof coverings and underlayment can blow off in high winds: sheathing can act as a water and wind barrier if the seams have been taped with a self-adhering bitumen tape
Proper underlayment installed per manufacturers’specifications with approved fasteners.
Roofs with a slope of less than 4/12 require two layers of approved 15# felt underlayment or a continuous ice and water barrier underlayment. Underlayment rows should overlap at least 4”
36Partnership for Advancing Technology in Housing
What? Proper Flashing
Valley, junction, and pipe penetration flashing:Installed wherever there is a change in surface plane or cladding material. Serves dual purpose of channeling water runoff during storm events and providing a second level of water intrusion protection. Roof edges should be flashed with a shingle starter strip or a self-adhering ice and water barrier. Apply a drip edge to all roof edges (including rake). Asphalt and fiberglass shingles should overlap the drip edge strip by at least ½” to ¾”. Meticulously follow building code and roof cladding manufacturers instructions.
Proper fastener/nailing schedulesPay specific attention to this detail - change with product and wind zoneEnsure that fasteners are installed to the proper embedment depth into framing members or sheathing - be aware of the depth that you set your automatic tools. Follow manufacturers specifications. Increasing the frequency of fasteners from four to six per shingle increases wind rating.
37Partnership for Advancing Technology in Housing
What? Hurricane Straps
Transfer loads from the gable truss/frame wall to the end wall below.
Ensure complete load paths at these pointsInstall metal straps rated for a minimum tensile load of 770
pounds at each lateral brace. Install wall sheathing so that it overlaps the connection between the
end wall and gable truss/frame by at least 12 inches.
38Partnership for Advancing Technology in Housing
PATH is…
…a public-private partnership that works to speed the development and adoption of advanced building technologies.
PATH works to add value to housingaffordabilityenergy efficiencyenvironmental impactqualitydurability and maintenancehazard mitigationsafety
39Partnership for Advancing Technology in Housing
PATH Partners
Federal AgenciesUniversities & ResearchersProduct
ManufacturersHomebuilders & DevelopersHousing
Institutions & Professionals Homeowners
40Partnership for Advancing Technology in Housing
Technology Pipeline
Research
Technology Development
Demonstration & Dissemination
Barrier Removal
Market Acceptance
Goal: Cut time-to-market for promising new technologies and procedures by half.
41Partnership for Advancing Technology in Housing
Partners in Innovation
PATH’s goal: making quality, affordable housing a reality
Energy EfficiencyEnvironmental PerformanceDurabilityDisaster ResistanceSafety
PATH acts as a catalyst for innovation in the homebuilding industry.
42
PATH ActivitiesTechnology Demonstrations
Barrier Removal Field
Evaluations
Research & Development
44Partnership for Advancing Technology in Housing
Separating the Wheat & the Chaff
Literature from product manufacturers may not provide the whole picture.
45Partnership for Advancing Technology in Housing
To learn more about the Tech Sets and other PATH resources, please visit our Web site:
www.pathnet.org