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Advanced Detailing Techniques for Building EnclosuresCOLIN SHANE M.ENG., P.ENG., P.E.
PRINCIPAL, 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.
APRIL 28, 2017
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 This presentation will provide an in-depth look at a variety of
wood-frame building enclosure assemblies and
details. Beginning with a review of building enclosure design
fundamentals and considerations, it will then focus on best
practices with references from technical guidelines and case
studies. Finally, the critical detail interfaces between different
enclosure assemblies (i.e., walls, roofs, balconies, windows,
foundations) will be reviewed with a focus on continuity of
critical barriers. A series of details and case studies will be
presented for each.
Learning Objectives
• Review building enclosure design best practices for light wood-frame buildings.
• Demonstrate effective methods of controlling heat, air, and moisture movement through wood-frame assemblies.
• Discuss common details used for light wood-frame wall and roof enclosure assemblies.
• Using case studies and details from past projects, demonstrate unique considerations and best practices associated with the interfaces between adjacent enclosure assemblies
6 of
Building Enclosure Design Fundamentals
à Separate indoors from outdoors, by controlling:
à Heat flow
à Air flow
à Vapor diffusion / condensation
à Water penetration
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!
7 of
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 Higher R-value requirements - thicker walls
à More insulation / less air leakage = less
heat flow to dry out moisture
à “Marginal” assemblies that worked in the past
may no longer work
à Amount, type and placement of insulations
matters
à Wetting / drying balance very important
8 of
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!
9 of
Wood-Frame Assemblies – ‘Pretty Good’ Wall
10 of
Wood-Frame Assemblies – ‘Perfect’ Roof
11 of
Details – Connect Control Layers
12 of
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?
13 of
Interfaces & Challenges
• DIFFERENTIAL MOVEMENT
• BALCONY INTERFACES
• EXTERIOR INSULATION
• …AND MORE
14 of
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
15 of
Design for Wood-Movement & Shrinkage
16 of
Behaviour of Wood in Construction
17 of
Wood Moisture Content vs Relative Humidity
Initial MC
Site/Construction
In-Service (Low)
In-Service (High)
Wood shrinkage is 0.20% to 0.25% in dimension per 1% change in MC
18 of
Behaviour of Wood in Construction
à Wood-frame Shrinkage
à Total shrinkage dependant on amount of tangential/radial grain wood and initial moisture content
à Differential movement is a real concern when detailing, especially for taller wood-frame buildings
à Shrinkage generally in range of ¼” per floor in dry cases, ½” per floor in typical cases, ~1” per floor in extreme cases
Cumulative Shrinkage for 6 storey Wood-frame Building at roof eave
19 of
Behaviour of Wood in Construction
à Detailing for Differential Shrinkage is Important
20 of
Lessons Learned from Wood-frame Shrinkage
21 of
Lessons Learned from Wood-frame Shrinkage
22 of
Window Sill Detail – Sealant Joint Method
23 of
Window Sill Detail – Sliding Flashing Method
24 of
Window Sill Detail – Sliding Flashing Method
25 of
Reducing Wood-frame Shrinkage - Floors
à Keep wood dry, watch saturation of floor framing during construction
à Engineered floor joists
à Modified platform framing practices
à Floor joists hang from top plate of wall, essentially reducing shrinkable wood at floor line
à Balloon framed details
26 of
Adapting Design & Architectural Style
27 of
Balcony Designs
28 of
Wood-Framed Balcony
à Cantilevered - likely the most common framing method
à Questions:
à Where is the air barrier?
à Thermal barrier?
à Water barrier?
à ‘Saddles’?
à Do we vent?
à Guardrail attachment?
29 of
Cantilevered Balcony – Control Layers
à Air barrier:
à Use the shortest path possible
à Prevent interior air from entering balcony soffit
à Vent soffit
à Thermal barrier:
à Remember ‘perfect’ wall
à Water barrier:
à Over a sloped and drained balcony surface
30 of
Cantilevered Balcony - Saddles
à 3-dimensional integration of assemblies
à Include a 3-dimensional detail
31 of
Cantilevered of Water Control Layer
32 of
Continuity of Air / Thermal Control Layers
à Air barrier and thermal barrier continuity often overlooked
à Difficult to reliably detail sheet membrane around penetrating joists
à Spray foam often used for air and thermal control
33 of
Continuity of Air / Thermal Control Layers
34 of
Pre-Finished Steel Balcony over Wood
à Balcony is a ‘bolt-on’ architectural component, but not part of building enclosure
à Air, water, and thermal control layers continuous behind pre-finished balcony
à Simplifies detailing – no saddles
à Continuous water, air, thermal layers
35 of
Bolt-On Balconies
36 of
‘Continuous’ Insulation
37 of
Building Enclosure & Passive Design
à Building enclosure is key element in passive design
à Exterior insulation is only as good as the cladding attachment strategy
à What attachment system works best thermally?
à Need to also consider:
à Structural
à Air / water tightness
à Constructibility
38 of
Many Cladding Attachment Options & Counting
39 of
Cladding Attachment: Vertical Steel Z-Girts
~65-75%+ loss in R-value
40 of
Cladding Attachment: Horizontal Steel Z-Girts
~45-65%+ loss in R-value
41 of
Cladding Attachment: Clip & Rail, Stainless Steel
42 of
Cladding Attachment: Proprietary Clip & Rail
à Numerous systems available
~5-30% loss in R-value (spacing & fastener type dependant)
43 of
Cladding Attachment: Continuous Wood Framing
~15-30% loss in R-value
44 of
Cladding Attachment: Screws through Insulation
Longer cladding Fasteners directly through rigid insulation (up to 2” for light claddings)
Long screws through vertical strapping and rigid insulation creates truss – short cladding fasteners into vertical strapping Rigid shear block type connection
through insulation, short cladding fasteners into vertical strapping
45 of
Publications / Research Reports
And many others!
46 of
Lab Examples and Testing
± 25 psf
47 of
Cladding Attachment: Screws Through Insulation
48 of
Exterior Insulation and Windows
à Need to provide a water shedding seal between exterior cladding and window
à With exterior insulation
exterior cladding is often
too far away
à Flashing or trim piece required to create continuity
49 of
Exterior Insulation and Windows
Summary
à Control moisture, air, and heat
à Best practices:
à Rainscreen cladding
à Keep structure warm and dry: control layers on exterior
à Think about the details!
à Provide continuity of control layers within and between assemblies and details
à Easier said than done: modern large buildings often architecturally complicated
à Walls, roofs, balconies, and…?
à rdh.com
Discussion + QuestionsColin Shanecshane@rdh.com
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