Presentation Outline: - Gravity support systems - Design criteria and thermal performance requirements - Canadian energy codes - Nominal vs. Effective R-Values - Thermal modeling and effective - R-values - Conclusions

1. Masonry Veneer Support Details:
Thermal Bridging
! Mike Wilson, MEng, P.Eng
Graham Finch, MASc, P.Eng
James Higgins, Dipl.T
RDH Building Engineering Ltd.
Vancouver, BC
June 3, 2013 – 12th Canadian Masonry Conference – Vancouver, BC

2. Presentation Outline
! Gravity support systems
! Design criteria and thermal
performance requirements
! Canadian energy codes
! Nominal vs. Effective R-Values
! Thermal modeling and effective
R-values
! Conclusions

3. Gravity Support Systems for Masonry Veneer
! Slab edge support

4. Gravity Support Systems for Masonry Veneer
! Edge-connected steel angles

5. Gravity Support Systems for Masonry Veneer
! Discretely connected steel angles

6. Design Criteria
! Structural
! Weight of masonry
! Type of connection
! Backup structural capacity
! Eccentricity of load
! Section properties of
support member
! Deflection
! Design criteria
! Esthetics
! Secondary effects
! Seismic allowance
! Joint frequency
! Backup movement
! Durability
! Material selection
! Compatibility of materials
! Environment conditions
! Thermal performance
! Design requirement

7. Overview: Canadian Energy Codes
! Part 9 (small buildings)
! National Building Code of Canada (NBC), 2010
! New energy provisions within 2012 update to Section 9.36
! Provinces adopt the NBC with modifications
! City of Vancouver (VBBL) is adoption of BCBC
! Compliance is generally prescriptive (R-value tables)
! Part 3 (large buildings)
! NBC and Provincial codes reference both:
• National Energy Code for Buildings (NECB), 2011 – previously the
MNECB 1997
• ASHRAE Standard 90.1 (Energy Code for Buildings Except Low-Rise
Residential)
! Compliance path options (prescriptive, trade-off, modeling)

8. Prescriptive Energy Code Requirements for Walls in Canada
Climate
Zone
Wall
–
Above
Grade:
Minimum
R-­‐value
(IP)
8
31.0
7
27.0
6
23.0
5
20.4
4
18.0
ASHRAE 90.1-2010 –
Residential Building
NECB 2011
Climate
Zone
Wall
(Mass,
Wood,
Steel):
Min
R-­‐value
8
19.2,
27.8,
27.0
7A/7B
14.1,
19.6,
23.8
6
12.5,
19.6,
15.6
5
11.1,
19.6,
15.6
*7A/7B combined in
ASHRAE 90.1
No climate zone 4 in
ASHRAE 90.1 –
bumped to zone 5

9. Effective vs. Nominal R-Values
! Effective R-values are required to
demonstrate compliance with Energy
codes most of the time
! Nominal R-values do not include impacts
of thermal bridging
! For example nominal R-20 batts within
steel studs becoming ~R-9 effective, or in
wood studs ~R-15 effective
! Masonry ties and shelf angles are also
thermal bridges that reduce effective R-values
significantly (even though a small
area)

10. How are “Effective” R-values determined?
! Effective R-values of Building Enclosure
Assemblies can be determined by:
! Hand methods – simple wood frame walls, not
suitable for accounting for thermal bridges
! Laboratory (Guarded hot-box testing) – good for
confirmation, expensive and not efficient for
multiple configurations
! Two-dimensional finite element thermal modeling
– not accurate for modeling discrete or
intermittent elements such as thermal bridges
! Three-dimensional finite element thermal
modeling – most accurate and cost effective.
Calibrated with laboratory testing to improve
accuracy.
! Heat3 (Blocon) – 3D finite element software
used for this analysis

11. Thermal Performance of Traditional Veneer Assemblies
! Modeling performed to look at effective R-values for
masonry veneer wall assemblies with alternate gravity
support systems
! Steel stud backup, concrete backup, and exposed slab
edge

12. Traditional Support Systems: Modelling Results

13. Thermal Performance of “Stand-off” Supports Systems
! Modeling performed to look at effective R-values for
masonry veneer wall assemblies with alternate types of
“stand-off” gravity support systems
! Knife plate, HSS Section, and overlapping angles
! Similar steel & mass and all connected at 48” o/c

14. “Stand-off” Support Systems: Modelling Results
Knife Plate HSS Structural
Section
Overlapping
Angles
shelf angle: 4”x4”x1/4”
outside of insulation.
4”x4”x3/4” stand-off knife
plates welded to embed
plates at 48” o.c.
shelf angle 4”x4”x1/4”
outside insulation.
4”x4”x1/4” HSS tube welded
to embed plates at 48” o.c.
shelf angle 4”x4”x1/4”
outside insulation.
2-6”x4”x5/16” angles bolted
to slab edge at 48” o.c.
Nominal Insulation
R-Value/U-Value
R-16.8 (RSI 2.95)
U-0.060 (USI 0.339)
R-16.8 (RSI 2.95)
U-0.060 (USI 0.339)
R-16.8 (RSI 2.95)
U-0.060 (USI 0.339)
Effective Assembly
R-Value/U-Value
R-14.8 (RSI 2.6)
U-0.068 (USI 0.384)
R-14.8 (RSI 2.6)
U-0.068 (USI 0.385)
R-15.0 (RSI 2.64)
U-0.067 (USI 0.379)
Effective Reduction 16.4% 16.5% 15.3%

15. Thermal Performance of “Proprietary” Supports Systems
! Modeling performed to look at effective R-values for
masonry veneer wall assemblies with alternate
proprietary gravity support systems

16. Proprietary Support Systems: Modelling Results
Standoff Bracket 4-Bolt Cast-In
shelf angle 4”x4”x1/4” outside
insulation. Proprietary clip is ¼” thick
steel, 4”x4”x1/4” 6” long C-section.
Non-welded connection.
Shelf angle 4”x4”x1/4” outside
insulation. Pre-manufactured cast-in
place thermal break connection with 4
stainless steel bolts attached to
7”x7”x 3/8” plate.
Nominal Insulation
R-Value/U-Value
R-16.8 (RSI 2.95)
U-0.060 (USI 0.339)
R-16.8 (RSI 2.95)
U-0.060 (USI 0.339)
Effective Assembly
R-Value/U-Value
R-14.9 (RSI 2.62)
U-0.067 (USI 0.381)
R-16.4 (RSI 2.9)
U-0.061 (USI 0.345)
Effective Reduction 16.4% 7%

17. Impact of Support Spacing

18. Conclusions
! Thermal bridging at masonry veneer supports is
significant and alone can impact the effective wall R-value
of an exterior insulated concrete wall by 27%
! Design details for “stand-off” conditions that are
relatively typical in the industry reduce the overall impact
of thermal bridging through continuous exterior
insulation to 15-17%
! Special measures are possible, utilising proprietary
systems to reduce the impact of thermal bridging below
10%

19. Questions
! Michael Wilson –mjw@rdhbe.com