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Building Enclosure Design and Best
Practices for Wood-Framed Buildings
COLIN SHANE M.ENG., P.ENG.
ASSOCIATE, SENIOR PROJECT ENGINEER
RDH BUILDING SCIENCES INC.
Disclaimer: This presentation was developed by a third party and is not
funded by WoodWorks or the Softwood Lumber Board.
MARCH 4, 2015
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. 2014
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
Through a combination of building science fundamentals, case studies, and current research, this presentation will explore best practices for designing durable, energy efficient building enclosures for mid-rise buildings constructed using traditional light wood-frame construction. Differences in enclosure design associated with taller wood-framed buildings using mass timber products will also be discussed.
Learning Objectives
Review building science fundamentals and building enclosure design considerations for light wood-frame buildings.
Discuss best practices for light wood-frame building enclosure design, detailing, and construction techniques
Compare the differences in building enclosure design criteria and systematic approaches between light wood-frame structures and tall, mass timber-frame structures.
Demonstrate examples of building enclosure details and assemblies used in light wood-frame projects and discuss lessons learned through case studies.
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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
2011 Building Enclosure Design
Guide – Wood-frame Multi-Unit
Residential Buildings
Emphasis on best practices,
moisture and new energy codes
2013 Guide for Designing Energy-
Efficient Building Enclosures
Focus on highly insulated wood-
frame assemblies to meet current
and upcoming energy codes
CLT Handbook
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Separate indoors from outdoors, by
controlling:
Heat flow
Air flow
Vapor diffusion
Water penetration
Condensation
Light and solar radiation
Noise, fire, and smoke
While at the same time:
Transferring structural loads
Being durable and maintainable
Being economical & constructible
Looking good!
Building Enclosure Design Fundamentals
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Trends in Building Enclosure Design
Trend towards more energy efficiently building enclosures
Air barriers now required in 2012 IECC and 2013 CEC
Continuous insulation becoming more common
Seeing more new building materials, enclosure assemblies and
construction techniques
More insulation = less heat flow to dry out moisture
“Marginal” assemblies that worked in the past may no longer
work
Amount, type and placement of insulations matters, for vapor, air
and moisture control
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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13
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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3 Conditions for Rain Penetration:
1. A source of water
2. A water entry path
3. A driving force
4 Ways to Control it:
1. Deflection
2. Drainage
3. Drying
4. 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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Code requirement
Moisture
Air holds moisture that can be
transported and deposited
within assemblies.
Energy
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
Air Barrier Systems Must:
Be continuous, airtight, durable
Resist structural loads
Bridge joints across inter-story
and drift joints
Not negatively affect drying
ability
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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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
Insulation between
studs is most
common heat control
strategy
Need to consider
effective R-values
Continuous insulation
on exterior becoming
more common
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Wood Framing Factor Impact
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Insulation Placement
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
Rain penetration control: rainscreen cladding
over water barrier
Air leakage control: robust air barrier system
Heat control: continuous insulation layer
Locate all barriers exterior of structure
Keep structure warm and dry
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
In practice, need to
evaluate and design
assemblies and details
that are not ‘perfect’
Continuity of control
layers within and
between assemblies is
critical
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
Keep it dry during construction – as best as possible
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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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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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Single family home
Moisture damage at walls and
windows
Concealed barrier stucco
cladding
Vented low-slope roof assembly
Energy efficient rehabilitation
of wall, window, and roof
assemblies
Deep Energy Retrofit
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Wall Rehabilitation
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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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Completed Building Enclosure
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Summary
Control moisture, air, and heat
Best practices:
Rainscreen cladding
Keep structure warm and dry:
control layers on exterior
‘Less than perfect’ practices:
Analyze and understand
hygothermal behaviour
Provide continuity of control layers
within and between assemblies and
details
This concludes The American Institute of Architects Continuing Education Systems Course
Joe Piñon – [email protected] Shane – [email protected] Hubbs – [email protected]
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Tallest wood structure in
North America
Cross Laminated Timber
panel construction
Next project will be 18
storeys
Wood Innovation Design Center
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Wood Innovation Design Center
Design & Architectural Renders: Michael Green Architecture (MGA)
