Post on 14-May-2020
transcript
1 of 63
Building Enclosure DesignFundamentals, Components, and Assemblies
COLIN 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.
JULY 11, 2018
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.
6 of 97
Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
7 of 63
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
8 of 63
à Supportà Structural loads
à Controlà Heat flow
à Air flow
à Vapor diffusion
à Water penetration
à Condensation
à Light and solar radiation
à Noise, fire, and smoke
à Finishà Being durable and maintainable
à Being economical & constructible
à Looking good!
Building Enclosure Design Fundamentals
9 of 63
The Old Way
10 of 63
The New Way – “Light & Tight”
11 of 63
Trends in Building Enclosure Design
à Trend towards more energy
efficiently building enclosures
à Air barriers now required in
2012 IECC
à Continuous insulation
becoming more common à More insulation = less heat
flow to dry out moistureà “Marginal” assemblies that
worked in the past may no
longer work
à Need to fully understand the science and interaction of design parameters
12 of 97
What do we know?
Building Enclosure
Control Air
Control Vapor
Control heat
Control Rain
13 of 63
Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
14 of 63
How do Walls get Wet and Dry?
15 of 63
Building Science: Wetting and Drying
à How can we keep the sheathing and other materials dry?
à Don’t let them get as wet
à Create air space to promote drying
à Design for vapor diffusion drying
à Keep sheathing warm
Drying
WettingSafe Storage Capacity
16 of 63
Water Penetration Control Strategies
17 of 63
Rainscreen Cladding
18 of 63
Rainscreen Cladding - Stucco
19 of 63
Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
20 of 63
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?
21 of 63
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)
22 of 63
Airtightness Does Not Happen By Accident
23 of 63
How to Tell the Membrane is Not the Air Barrier
24 of 63
Definitely Not An Air Barrier… But What Is?
25 of 63
Testing Air Barrier Systems
26 of 63
Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
27 of 63
ClimateZone
IECC 2015Above Grade Walls:
Min. Eff. R-value
Steel Wood
7 15.6 / 19.2 19.6
6 15.6 / 17.5 19.6
5 & 4C 15.6 15.6
4 A/B 15.6 15.6
3 15.6 15.6
2 13.0 / 15.6 15.6
1 13.0 15.6
Based on Maximum Effective Assembly U-value Tables (C402.1.2 (2012), C402.1.4 (2015))
Residential Building R-values buildings similar or in some cases slightly higher
Targets for Walls in Comm/Res Buildings
28 of 63
Conductive Heat Loss Control
29 of 63
Conductive Heat Loss Control
à Insulation between studs is most common heat control strategy
à Need to consider effective R-values
à Wood ± R-1 per inch
à “Continuous insulation” may be required in some climate zones per IECC
30 of 63
0
2
4
6
8
10
12
14
16
18
20
22
24
0 5 10 15 20 25 30 35 40
Overa
ll E
ffect
ive R
-Valu
e (
oF f
t2h
r/Btu
)
Framing Factor %
Steel 2x6 StudSteel 3 5/8 Stud
Wood 2x6 Stud
Wood 2x4 Stud
Framing Effect on R-values
Fram
ing @
16”
o.c
.
31 of 97
Insulation Placement
à Consider effective thermal resistance, vapor diffusion
profile, and relative durability
32 of 97
The Old WayThe Standard Approach
à Assembly
à ½” gyp
à 2x6 @ 16” o.c.
à R-20 high density insulation
à ½” sheathing
à WRB/furring/cladding
à Standard framing factor
à 77% cavity, 23% framing
à U-0.064
à R-15.6
33 of 97
à Assembly
à ½” gyp
à 2x8 @ 16” o.c.
à R-30 high density insulation
à ½” sheathing
à WRB/furring/cladding
à Standard framing factor
à 77% cavity, 23% framing
à U-0.045
à ± R-22.0
New Option #1Higher R-Values - Option #1
34 of 97
à Assembly
à ½” gyp
à 2x6 @ 16” o.c.
à R-21 high density insulation
à ½” sheathing / WRB
à 1” insulation (R-4.2 cont.)
à Furring/cladding
à Standard framing factor
à 77% cavity, 23% framing
à U-0.046
à ± R-22
Higher R-Values - Option #2
35 of 97
So, What’s the Difference?
R-22 R-22
36 of 97
Exterior Insulation Selection (Vapor Control)
à Rigid exterior foam insulations (XPS, EPS,
Polyiso, closed cell SPF) are vapor
impermeable
à Rules of thumb: Vapor barrier on ‘warm’ side
à Fibrous insulations (mineral fiber / glass
fiber) are vapor permeable
à Allows drying to the exterior
à Often safer in cold and mixed climates
à Vapor permeance properties of WRB/air
barrier membrane is also very important
37 of 97
Building Science: Wetting and Drying
à How can we keep the sheathing and other materials dry?
à Don’t let them get as wet
à Create air space to promote drying
à Design for vapor diffusion drying
à Keep sheathing warm
Drying
WettingSafe Storage Capacity
38 of 63
Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
39 of 97
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!
40 of 97
Wood-Frame Assemblies – ‘Perfect’ Wall
41 of 97
Wood-Frame Assemblies – ‘Perfect’ Roof
42 of 63
Wall-to-Roof Detail
43 of 63
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
44 of 63
Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
45 of 63
Cross Laminated Timber – Ronald McDonald House
46 of 97
CLT – Construction Moisture
à Keep it dry during construction – as best as possible
47 of 63
CLT – Wall Assemblies
48 of 63
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)
49 of 63
à Get the architect to take the final photos
CLT Considerations
50 of 63
Basics
Water
Air
Heat
BACKGROUND
Walls
Low-slope Roofs
Steep-slope Roofs
BEST PRACTICES
CLT
Deep Energy Retrofit
CASE STUDIES
Roadmap
51 of 63
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
52 of 63
5-Storey Wood-frame w/ Exterior Insulation
53 of 63
New Exterior Wall Assembly
54 of 63
New Sloped Roof / Overhang Assembly
55 of 63
New Low-Slope Roof Assembly
56 of 63
Completed Building Enclosure
57 of 97
Summary
à Control moisture, air, and heat
à Best practices:
à Drained & ventilated claddingà Keep structure warm and dry:
control layers on exterior
à ‘Less than perfect’ practices:
à Analyze and understand wetting / drying balance
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 – cshane@rdh.comwww.rdh.com
59 of 63
à rdh.com
Discussion + Questions
Colin Shane – cshane@rdh.com