3/2/2012 1 Evaluating the Performance of Plaster Assemblies in Climate Zone 6 Welcome the OPUS Group August 17, 2011 Stringent new changes to the way we construct buildings are on the horizon. The Minnesota Lath and Plaster Bureau and Third Level Design recognize the benefits and the pitfalls of these changes. It is this unique partnership that we feel will help you navigate the best strategy to meet those changes. Steve Pedracine CSI, CDT, CEI David Bryan AIA, LEED
Transcript
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Evaluating the Performance of Plaster Assemblies in Climate Zone 6
Welcome the OPUS GroupAugust 17, 2011
Stringent new changes to the way we construct buildings are on the horizon. The Minnesota Lath and Plaster Bureau and Third Level Design recognize the benefits and the pitfalls of these changes. It is this unique partnership that we feel will help you navigate the best strategy to meet those changes.
Steve PedracineCSI, CDT, CEI David Bryan
AIA, LEED
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The Minnesota Lath and Plaster Bureau and Third Level Design are Registered Providers with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members are available on request.
This program is registered with the AIA/ CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling using distributing or dealing in any material or product.
Understand the advantages of locating rigid insulation to the exterior of traditional wall assemblies.
Be aware of the energy code implications and thermal consequences of interrupting exterior insulation with framing members.
Set air tightness targets for a building enclosure.
Value the risk of moisture intrusion
Be able to define durability issues that diminish or increase Life Cycle of Stucco and EIFS
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Lawrence Berkley Laboratories
Building Green
Total Energy Use in Homes
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2010 2015 2020 2025 2030
Estimated Energy Use Reduction relative to Current Building Codes (IECC 2006 & ASHRAE 90.1 2004)
Architecture 2030
2007 Energy Independencence and Security Act for Federal Buildings
ASHRAE 90.1
ASHRAE 189.1 Green Building Code
Minnesota is currently using ASHRAE 90.1- 2004/2006 IECC The next evolution is ASHRAE 90.1-2007/2009 IECC or beyond
Continuous Insulation” in prescriptive requirements is “uninterrupted by framing”If framing interrupts insulation, thermal bridging corrections must be applied
Nominal Correction Actual XPS (R5)Insulation Type R-value Factor R-value Thickness
Fiberglass Cavity Insulation 19 .81 15.4
Other Materials 2.0 1.0 2.0
“Continuous” Exterior Insulation 3.7 1.0 3.7 3/4”
Total Wall R-value 21.1
Alternative wall assembly: Zero cavity insulation, exterior XPS only
Nominal Correction Actual XPS (R5)Insulation Type R-value Factor R-value Thickness
Cavity Insulation 1.0 2.5 2.5
Other Materials 2.0 1.0 2.0
Exterior Insulation 20 .81 16.2 4”
Total Wall R-value 20.7
Continuous Insulation” in prescriptive requirements is “uninterrupted by framing”If framing interrupts insulation, thermal bridging corrections must be applied
Example: Design an R19.6 wood stud wall (2x6’s,16”o.c.)
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Base Wall Materials R = 2.0R19 Fiberglass x .81 R = 15.43/4 ” R5 XPS R = 3.7
Cost /SF per actual R = $0.09 Total = 21.1
Base Wall Materials R = 2.0R13 Fiberglass x .81 R = 10.51.5” R5 XPS R = 7.5
Cost /SF per actual R = $0.11 Total = 20.0
Base Wall Materials R = 2.0No Cavity Insulation R = 2.54” R5 XPS x .81 R = 16.2
Cost /SF per actual R = $0.19 Total = 20.7(Includes extra sheathing and furring)
Moisture Movement Mechanisms
from: “Insulations, Sheathings and Vapor Diffusion Retarders”, Building Science Corporation 2003
Higher air pressure Lower air pressure
• Air flow through visible cracks and holes• Water vapor is carried by the air
Higher water vapor concentration
Lower water vapor concentration
• No air flow• Water vapor flow through tiny pores
Av. for U.S. Residential Housing Stock since 1993 (~.5 ACH)
DOE Building America Residential Enclosure Standard (~.29 ACH)
"Regularly achievable..if airtightness details are tested", Residential, John Straube (~.22 ACH)
Passivhaus Standard (~.04 ACH)
ASHRAE 90.1 2007 compliance option
Commercial Residential
How do you design moisture-tolerant building enclosures?
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Wall Assembly Test Facility in Charleston, South Carolinaby Oak Ridge National Laboratories
One of many sites used to validate WUFI results against actual performance
Field Validation Example:
Building enclosure performance is very sensitive to material properties, construction practices and interior relative humidity - so designs should be “fault tolerant”
Stucco is appropriate for our climate with proper detailing and construction practices
Vapor retarders integral to fiberglass batts, like Kraft paper, can suffer vapor bypass at the edges and don’t perform as well as sheet products that cover the entire wall
Smart vapor retarder systems (polyamide films) perform better than polyethylene
A Simulation Investigation of Stucco Cladding Wall System Vapor Transport Performance in a Cold Climate, Goldberg, University of MN, 2006 and Cloquet Residential Research Facility: Wall Systems Hygrothermal Performance Experimental Evaluation, University of MN, Goldberg and Huelman, 2009
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Certainteed
Driving rain penetration is an important part of the WUFI analysis
Minneapolis
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Base Wall Materials R = 2.0R19 Fiberglass x .81 R = 15.41” x R3.6 (Type I EPS) R = 3.6
Cost /SF per actual R = $0.44 Total = 21.0
Base Wall Materials R = 2.0R13 Fiberglass x .81 R = 10.52” x R3.6 (Type I EPS) R = 7.2
Cost /SF per actual R = $0.48 Total = 19.7
Base Wall Materials R = 2.0No Cavity Insulation R = 2.54” x R3.6 (Type I EPS) R = 14.4
Cost /SF per actual R = $0.50 Total = 18.9
Rout to R in = .2
Sheathing Conditions for .40 cfm/ft2 @ 75 Pa infiltration
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Rout to R in = .8
Sheathing Conditions for .40 cfm/ft2 @ 75 Pa infiltration
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Sheathing Conditions for av. residential building infiltration
Infiltration Control is Important !
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Stay on this side of linefor OSB or Plywood Sheathing
.50
Stay on this side of linefor Gypsum Sheathing
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For Climate Zone 6 and normal interior moisture levels:
1. Choose the most vapor-permeable components that do the job
2. Use a smart vapor retarder
3. Control Infiltration – detail, specify & test
4. Avoid interrupting exterior insulation with metal framing
5. Ratio of insulation R-value outside sheathing to R-value inside sheathing:
for Surface Burning Characteristics (IBC 2603.3, 2603.5.4)
ASTM E 119-07, Standard Test Method for Fire Tests of Building Construction and Materials (IBC 2603.4)
NFPA 259-04, Test Method for Potential Heat of Building Materials Rated Assemblies (IBC 2603.5.3)
NFPA 268-07, Standard Test Method for Determining Ignitability of Exterior Wall Assemblies (IBC 2603.5.7)
NFPA 285-06, Standard Method of Test for the Evaluation of Flammability Characteristics of Exterior, Nonload-bearing Wall Assemblies Containing Combustible Components (IBC 2603.5.5) . Applies to Type I, II, III, IV > 1 story
Foam Plastic Coatings
Foam Plastic Coatings
Thermal Barrier Thermal Barrier
Foam Plastic Foam Plastic
Stucco Exception System
SystemNot tested
Dow Thermax is tested
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STUCCO EIFS
Crack Resistance: Fair Brittle nature subject to
minor structural movement.
Minimal fastener installation of insulation board transfers stress to coating.
Susceptible to shrinkage cracks due to volumetric change.
Crack Resistance: Good Coating flexible to
accept minor structural movement.
Notched trowel adhesion of insulation board minimizes transference of stress to coating.
WRB affected by exposure to weather.• Building Paper 30 days.•Polymeric wrap 4 months
WRB punctured by fasteners•Staples, discs.•Lath attachment
•Seamless Water-Resistive Barrier (WRB)•WRB Unaffected by exposure to weather.•Minimal punctures by fasteners•Insulation board adhered by notched trowel.
STUCCO EIFS
“It is clear from these results that (the proprietary EIFS) system specimen tested, allowed fast…and complete drainage. This matches our extensive testing experience that gaps as thin as a that of a dime (1 mm) drain water quickly and well.”
John Straube, P.Eng., Department of Civil Engineering and School of Architecture , University of Waterloo.
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STUCCO EIFS
Interlacing of hydrated crystals
40 F or better during installation
Must be kept from freezing
Requires water misting Polymer modification
(optional) Must cure 7-14 days
before finish applied
Evaporation 40 F or better for 24
hours
Ready to finish in 24 hours.
STUCCO EIFSSTUCCO/EIFS
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STUCCO EIFS
Lath, cement, aggregate, accessories, insulation board may all come from different sources.
Warranty: None
Insulation Board by another party, to manufacturers specs.
All remaining components by single source
Warranty: Dependent upon system
components Material / Material and
Labor Up to 15 years.
STUCCO EIFS
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STUCCO EIFS
STUCCO EIFS
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Mock-up of the wall assembly should be constructed and reviewed prior to construction.
The construction of the wall assembly is an extension of the design process. It is essential that workmanship-sensitive materials and systems receive due attention in the construction process.
As such, periodic or full time inspection of a given EIFS installation should be considered mandatory by prudent designers and owners alike.
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Cost Lifetime Maintenance Continuous LifecycleInsulation CO2
EIFS Lower Cost 25-50 yrs Recaulk @ 20 yrs Up to 4” 1686Regular Cleaning (R15) easy gms/SF
Stucco Higher Cost 100 + yrs Recaulk @ 20 yrs Up to 2” 4906Regular Cleaning (R10) easy gms/SF
