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The Role of Control Layers in Building Enclosure Design
COLIN SHANE M.ENG., P.ENG., P.E.
ASSOCIATE, SENIOR PROJECT MANAGER
RDH BUILDING SCIENCE INC.
Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board.
SEPTEMBER 14, 2016
This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written
permission of the speaker is prohibited.
© RDH Building Sciences Inc. 2015
Copyright Materials
“The Wood Products Council”is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider #G516.
Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.
This course is registered with 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.__________________________________
Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Course Description
à Building enclosures are responsible for controlling heat flow,
air flow, vapor flow and a number of other elements. Through
a combination of building science fundamentals and current
research, this presentation will explore design considerations
associated with wood-frame building enclosures and the role
of control layers. Discussion will focus on best practices for
designing durable, energy-efficient enclosures using
traditional light wood-frame construction.
Learning Objectives
à Review building science fundamentals and building enclosure
design considerations for light wood-frame buildings.
à Explore the role of control layers in building enclosures for
elements such as heat flow, bulk water intrusion and air flow.
à Discuss best practices for light wood-frame building enclosure
design, detailing, and construction techniques.
à Explore the thermal benefits of utilizing wood-frame construction.
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Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
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Wood-frame Building Enclosure Design Guides
à 2011 Building Enclosure Design
Guide – Wood-frame Multi-Unit
Residential Buildings
à Emphasis on best practices,
moisture and new energy codes
à 2013 Guide for Designing Energy-
Efficient Building Enclosures
à Focus on highly insulated wood-
frame assemblies to meet current
and upcoming energy codes
à CLT Handbook
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à Separate indoors from outdoors, by controlling:à Heat flow
à Air flow
à Vapor diffusion
à Water penetration
à Condensation
à Light and solar radiation
à Noise, fire, and smoke
à While at the same time:à Transferring structural loads
à Being durable and maintainable
à Being economical & constructible
à Looking good!
Building Enclosure Design Fundamentals
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Trends in Building Enclosure Design
à Trend towards more energy efficiently building enclosures
à Air barriers now required in 2012 IECC and 2013 CEC
à Continuous insulation becoming more common
à Seeing more new building materials, enclosure assemblies and
construction techniques
à More insulation = less heat flow to dry out moistureà “Marginal” assemblies that worked in the past may no longer
work
à Amount, type and placement of insulations matters, for vapor, air
and moisture control
à Need to fully understand the science and interaction of design parameters
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What do we know?
Building Enclosure
Control Air
Control Vapor
Control heat
Control Rain
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Building Enclosure Control Layers
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Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
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à 3 Conditions for Rain Penetration:
1. A source of water2. A water entry path3. A driving force
à 4 Ways to Control it:
1. Deflection2. Drainage3. Drying4. Durability
Rain Penetration Control
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How do Walls get Wet and Dry?
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Water Penetration Control Strategies
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Rainscreen Cladding
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Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
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à Code requirement
à Moistureà Air holds moisture that can be
transported and deposited
within assemblies.
à Energyà Unintentional airflow through
the building enclosure can
account for as much as 50%
of the space heat loss/gain in
buildings.
Air Penetration Control – Why?
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Air Barrier Systems
à Air Barrier Systems Must:à Be continuous, airtight, durable
à Resist structural loads
à Bridge joints across inter-story
and drift joints
à Not negatively affect drying
ability
à Traditional loose sheet applied house-wrap products are challenging to make air-tight on larger buildings
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Types of Air Barrier Systems
Sealed Gypsum Sheathing –Sealant Filler at Joints
Loose Sheet Applied Membrane –Taped Joints & Strapping
Liquid Applied – Silicone sealants and silicone membrane at Joints
Sealed Plywood Sheathing –Sealant & Membrane at Joints
Sealed Sheathing –Membrane at Joints
Self-Adhered vapor permeable membrane
Plywood sheathing with taped joints (good tape)
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Airtightness Does Not Happen By Accident
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How to Tell the Membrane is Not the Air Barrier
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Definitely Not An Air Barrier… But What Is?
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Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
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Conductive Heat Loss Control
à Insulation between studs is most common heat control strategy
à Need to consider effective R-values
à Continuous insulation on exterior becoming more common
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Wood Framing Factor Impact on Effective R-values
Fram
ing
@ 1
6”
o.c
.
Fram
ing
@ 2
4”o
/c
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Insulation Placement
à Consider effective thermal resistance
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Cladding Attachment Through Exterior Insulation
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Cladding Attachment through Exterior Insulation
Longer cladding Fasteners directly through rigid insulation (up to 2” for light claddings)
Long screws through vertical strapping and rigid insulation creates truss (8”+) – short cladding fasteners into vertical strapping Rigid shear block type
connection through insulation, cladding to vertical strapping
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Thermally Improved Performance
Continuous metal Z-girts
Fiberglass Clips & Hat-Tracks
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Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
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The ‘Perfect’ Assembly
à Rain penetration control: rainscreen cladding
over water barrier
à Air leakage control: robust air barrier system
à Heat control: continuous insulation layer
à Locate all barriers exterior of structure
à Keep structure warm and dry
à 50+ year old concept!
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Wood-Frame Assemblies – ‘Perfect’ Wall
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Wood-Frame Assemblies – ‘Perfect’ Roof
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Wood-Frame Assemblies – ‘Perfect’ Roof
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Wall-to-Roof Detail
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Wall-to-Roof Detail
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Details – Continuity of Control Layers
à In practice, need to evaluate and design assemblies and details that are not ‘perfect’
à Continuity of control layers within and between assemblies is critical
à Hygrothermal analysis
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Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
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Cross Laminated Timber – Ronald McDonald House
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CLT – Construction Moisture
à Keep it dry during construction – as best as possible
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à Structural connections can interfere with air-barrier membrane installation/sequencing and sharp parts can damage materials (applied before or after)
CLT – Air Barrier Considerations
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CLT – Unique Details for Consideration
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CLT Panel Details Requiring Attention
Sealants, tapes, & membranes applied on either side can’t address this type of airflow path through the CLT lumber gaps
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CLT – Wall Assemblies
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Roof Assembly
R-40+ Conventional Roof Assembly – 2 ply SBS, 4” Stonewool, 4” Polyiso, Protection board, Tapered EPS (0-8”), Torch applied Air/Vapor Barrier(Temporary Roof), ¾” Plywood, Ventilated Space (To Indoors), CLT Roof Panel Structure (Intermittent)
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à Get the architect to take the final photos
CLT Considerations
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Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
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à Moisture damage at walls
and windows
à Concealed barrier stucco
cladding
à Vented low-slope roof
assembly
à Energy efficient
rehabilitation of wall,
window, and roof
assemblies
Deep Energy Retrofit
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5-Storey Wood-frame w/ Exterior Insulation
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New Exterior Wall Assembly
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New Sloped Roof / Overhang Assembly
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New Low-Slope Roof Assembly
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Completed Building Enclosure
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Summary
à Control moisture, air, and heat
à Best practices:
à Rainscreen claddingà Keep structure warm and dry:
control layers on exterior
à ‘Less than perfect’ practices:
à Analyze and understand hygothermal behaviour
à Provide continuity of control layers
within and between assemblies and
details
This concludes The American Institute of Architects Continuing Education Systems Course
Colin Shane – [email protected]
