NNCA Construction Workshop
2016-02-17
Optimal High R-value Wall Designs for the
Far North – Balancing the Science & Practice
NNCA RESIDENTIAL CONSTRUCTION WORKSHOP, YELLOWKNIFE – FEB 17, 2016
GRAHAM FINCH, MASC, P.ENG – PRINCIPAL & BUILDING SCIENCE RESEARCH SPECIALIST
[email protected] – 604-873-1181
Presentation Outline
G.Finch - RDH
Northern Building & Energy
Code Requirements & Local Wall
Designs
Building Science Considerations
for Higher R-value Wall
Assemblies
Optimal Wall Study - R-40 Wall
Evaluation
Thermal Performance
Hygrothermal Durability
Constructability, Cost, &
Resource Efficiency
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NNCA Construction Workshop
2016-02-17
Building Science Challenges in the North
The North is the most challenging environment
to construct, operate & maintain a building
Extreme cold requires super-insulated enclosure
assemblies, minimal thermal bridging and nearperfect air-sealing
HVAC systems must be reliable, easy to operate
and have redundancy
Snow, ice, wind, permafrost all add further
unique building design considerations
Indoor humidity & providing adequate ventilation
is often a challenge (and even more so as we
build more airtight) – Topic of Day 2
Not all building materials are readily available
here
Not all materials can be applied, work as well or
hold-up in the extreme cold
Building & Energy Code Drivers in the North
G.Finch - RDH
2010 National Building Code
(Plus 2012 Part 9.36 Energy Efficiency
Requirements)
NECB 2011 (Replaced old MNECB 1997)
Municipal Bylaws & Territorial
Guidelines have additional/modified
enclosure requirements
In all cases - emphasis is placed on well
insulated, air-tight and thermal bridge
free building enclosures
General shift in mind-set from nominal
(insulation only) to effective R-values
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NNCA Construction Workshop
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Nominal vs Effective R-values of Insulation
Nominal R-values = Rated R-values
of insulation which do not include
impacts of how they are installed
For example R-20 batt insulation or
R-10 rigid insulation boards
Effective R-values or Real R-values
= Calculated R-values of
assemblies/details which the
include impacts of installation and
thermal bridges (studs, girts etc)
For example nominal R-20 batts
within 2x6 steel studs 16” o.c.
becoming ~R-9 effective, or in
wood studs ~R-15
Minimum Code R-values – Canada’s North
Effective R-values (includes impact of thermal bridging)
Building/Energ
y Code
Requirement –
Climate Zone 8
Walls:
Minimum
R-value (IP)
Roofs –
Compact or
Attic:
Minimum Rvalue (IP)
Floors suspended:
Minimum
R-value (IP)
NBC 2010
(2012 Part
9.36) – Part 9
Buildings
21.9
(17.5 if
HRV
installed)
28.5 (flat)
59.2 (attic)
28.5
NECB 2011 –
Part 3
Buildings
31.0
40.0
40.0
All Values for most extreme Climate Zone 8
(>7000 HDD incl. NT, NU, & most YT)
G.Finch - RDH
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NNCA Construction Workshop
2016-02-17
Beyond Minimum Code R-values – Far North
Guideline, Bylaw
or Green Standard
Walls: Minimum
R-value (IP)
Roof – Ceiling below
Attic: Minimum Rvalue (IP)
Floor
(suspended):
Minimum Rvalue (IP)
Nunavut – Good
Building
Practices, 2005
R-28
(nominal)
R-40
(nominal)
R-40
(nominal)
NWT – Good
Building
Practices, 2011
R-32
(nominal)
R-50
(nominal)
R-40
(nominal)
Yellowknife –
Existing Buildings
R-30
(nominal)
R-40
(nominal)
R-30
(nominal)
R-28 Whitehorse
R-21.9 elsewhere
(effective)
R-59 (effective)
R-28.5
(effective)
R-60 to R-80+
(effective)
R-60 to R-100+
(effective)
R-40 to R-60+
(effective)
Yukon Housing
Corporation
General Passive
House Guidelines
Note: Several Documents Refer to Nominal Insulation R-values not Effective
Residential Wall Design Preferences to Meet R-28
to R-30 Nominal Target in the Far North
G.Finch - RDH
R-22 fiberglass batts + R-6 semi-rigid mineral wool
interior (R-30 nominal) w/24” stud spacing ~R-22
effective
Poly VB/AB, Housewrap WRB/(AB?)
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NNCA Construction Workshop
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Many Other Wall Designs Being Built - Yukon
EPS/MW
R-36 effective
FG/EPS/FG
R-40 effective
ccSPF/PIC/MW
R-44 effective
ocSPF/MW
R-51 effective
EPS/EPS/MW
R-36 effective
CFI/
MW
EPS/MW
ocSPF/
MW
SIPS
/MW
MW/ccSPF/FG
R-43 effective
R-52 effective
R-51 effective
R-56 effective
R-53 effective
From Craig Olsen & Lysann Grundlich “Breaking Down Barriers to Building SuperGreen”
Making the Leap to Higher R-values (R-40+)
Exterior Insulation
R-20 to R-60+
Base 2x6
Framed
Wall ~R-16
Deep
Stud,
Double
Stud,
SIPS
R-20 –
R-80+
Split Insulation
R-20 to R-80+
G.Finch - RDH
Interior Insulation
R-20 to R-30+
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NNCA Construction Workshop
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How to Evaluate Different Wall Designs?
High R-value Wall Assembly Design & Detailing –
Choices for Control Functions
(WSS)
(WRB)
(AB)
(VR/VB)
(Insulating Materials)
G.Finch - RDH
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NNCA Construction Workshop
2016-02-17
Rainscreen Claddings (Water Shedding Surface)
For highly insulated walls suggest
drained & ventilated cavity
behind cladding (i.e. Rainscreen)
Helps facilitate drying of wall &
cladding and reduce capillary or
vapour transfer of moisture to
back-up wall
Vertical strapping (furring), girts
or other materials to create the
gap
Select appropriate material
suitable for north (i.e. metal,
wood, fiber cement)
Cladding attached to vertical
strapping
The Water Resistive Barrier (WRB)
G.Finch - RDH
Often referred to as the “sheathing
membrane”
Required in all walls – is the 2nd
plane of protection & innermost
plane that can safely manage
moisture and drain/dry it back out
Many different products available
(mechanically fastened, selfadhered, & liquid applied)
Many products can also be
taped/sealed/applied as air barrier
Vapour permeable & impermeable
products available – choice depends
on insulation placement etc.
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NNCA Construction Workshop
2016-02-17
Thermal Control - Insulation
Many different types of
insulation products
Low density batts
Loose fill (blown/spray)
Semi-rigid or rigid boards
Spray-applied foam
New materials like VIPs,
aerogels
Key properties to consider:
Conductivity (R-value)
Air permeability
Vapour permeability
Density & application
Insulation R-values
G.Finch - RDH
Recent research has re-highlighted the fact that the Rvalue of insulation is not always constant (or as
published)
Aged R-values (Long-term Thermal Resistance)
Temperature Dependant R-values
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Varying Insulation R-value with Temperature
It Gets Even More Complicated with Polyiso
Temperature Dependence of Polyiso Thermal Performance
Temperature [°F]
14
32
50
68
86
104
122
7.0
0.021
6.5
0.022
6.0
0.024
5.5
0.026
5.0
0.029
4.5
0.032
4.0
0.036
3.5
0.041
3.0
Conductivity, k [W/(m·K)]
R-Value per Inch [(hr·ft²·°F/Btu)/in]
-4
0.048
-20
-10
0
10
20
30
40
50
Temperature [°C]
01 (1995 to 1996)
04 (2006)
07 (2007 to 2009)
10 (2012)
12b (2012)
G.Finch - RDH
02 (1995 to 1996)
05 (2006)
08 (2009)
11 (2012)
03 (1999)
06 (2006)
09 (2009)
12a (2012)
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NNCA Construction Workshop
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Vapour Retarders / Barriers
Vapour Retarders / Barriers
control the diffusion of vapour
through an assembly
Limit wetting (condensation)
At the same time we need to
allow for some drying
Many materials act as vapour
retarders even if unintended
In Far North – vapour control on
warm side of insulation*
Gets more complicated with
exterior/split insulated
assemblies & with vapour
impermeable insulation
Design for Vapour Diffusion Drying Ability
G.Finch - RDH
Watch over-use of impermeable
materials over damp materials
or materials that could get wet
in-service
Self adhered membranes
Foam plastic insulation
Vapor diffusion wetting &
drying ability for assemblies &
details should always be
assessed at design stage
In the north – especially for
northern facing walls – very
limited potential for vapour
diffusion drying
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Air Barrier Systems
Air Barriers are Systems – always
more than one material/component
Details are the most critical part
5 Requirements of an effective
Air Barrier System
Air-impermeable
Continuous
Structurally Adequate
Sufficiently Rigid (or supported)
Durable
Plus: Must not negatively restrict
vapour diffusion drying ability
Air Barriers Are Systems
Materials
Components
Accessories
Whole
Building
Airtightness
G.Finch - RDH
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NNCA Construction Workshop
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Different Wall Air Barrier Systems
Preference depends on a
variety of factors including
enclosure design & builder
familiarity with system
Common Air Barrier Systems
Sealed polyethylene (mastic
& tapes)
Airtight drywall
(drywall/gaskets/sealant)
Taped & sealed
mechanically attached
sheathing membranes
Self-adhered or liquid
applied sheathing
membranes
Sealed Sheathing
(sealants/tapes at Joints)
Spray Polyurethane Foam
(sealants at interfaces)
Robust Wall Air Barrier Systems for the North
G.Finch - RDH
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NNCA Construction Workshop
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Interior vs Exterior Air Barrier with Cavity Walls
Industry shift away from the use of interior air barrier approaches (poly,
drywall) to favouring exterior sheathing approaches (sheathing
membranes, sheathings) as the primary air barrier element
BUT! still need to maintain a reasonable degree of airtightness at interior
side of fibrous cavity insulation (convection suppressor) – especially in
the Far North
Vapor barrier/retarder at interior side depending on insulation ratio
With enough exterior insulation – risk for condensation at
sheathing decreases as does need for interior air tightness
Primary Air Barrier System
Secondary Airtight element
Optimal Design for High R-value
Wall Assemblies in Northern
Canada
G.Finch - RDH
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NNCA Construction Workshop
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Optimal Northern Wall Design Prerequisites
Walls are subject to extreme cold, intense
winds and unique solar exposure, therefore
walls must be able to:
Support structural loads: wind & lateral
loads, gravity
Control environmental loads:
› Moisture - precipitation, blowing snow, air
leakage condensation, indoor water vapour
› Air – continuous air barrier system to
minimize heat loss and control condensation
› Heat –sufficient thermal resistance to
minimize losses & gains
› Noise & fire – by using appropriate materials
Finish: Durable finish resistant to exterior
and interior impact loads/use
Be affordable, simple to build & maintain,
be minimal weight/volume for shipping
Optimal Northern Wall Design Considerations
G.Finch - RDH
Durability & Longevity
Material & Labour Cost
Material Availability
Ease of Construction
Pre-fabrication vs Site-Built
Thickness
Weight (shipping and/or site handling)
Environmental aspects (material choice)
Air Barrier System & Detailing
Water & Vapour control (wetting & drying)
Cladding Attachment, Finishes
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NNCA Construction Workshop
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Optimal Wall Research - Why R-40 Wall Target?
Work by NRCan/CMHC has identified a target of R-40
effective for walls as it is cost, energy & resource
optimal for Northern Canadian housing archetypes
Current minimum code targets in North are in the R-20
to R-30 effective range (and climbing) so future target?
Many builders already constructing R-30 to R-60 walls
as part of more energy efficient home designs
For optimization study here was a good baseline target
to strive for
R-40 is easily scalable up (e.g. R-60+) or down
(e.g. R-30) by simply varying the thickness of
insulation layers
Primary R-40 Wall Types & Insulation Variations
Interior Insulated
(Double/Deep
Stud Cavity
Insulated)
G.Finch - RDH
Exterior
Insulated
Split Insulated
(Exterior & Stud
Cavity)
Insulated
Structures (SIPs)
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NNCA Construction Workshop
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Interior Insulated – Deep/Double Stud Walls
Water Control:
Vapour Diffusion Control:
Sealed polyethylene at interior
Air Control*:
Drained/ventilated rainscreen cladding
with synthetic housewrap WRB
Caulked and taped poly at interior,
sealed housewrap at exterior or sealed
plywood at exterior. Alternate –
sprayfoam between studs or secondary
interior service wall
Cost/Constructability:
SPF/blown cellulose requires special
equipment & training
Double framed wall requires extra labour
Structurally Insulated Panels - SIPs
Water Control:
Vapour Diffusion Control:
G.Finch - RDH
OSB interior skin/EPS core
Air Control*:
Drained/ventilated rainscreen
cladding with synthetic housewrap
WRB
Sealed OSB joints and EPS foam at
interior & exterior
Cost/Constructability*:
Expensive material, though less
labour and prefabrication speeds
up construction
Requires specialized training and
local crane/lifting equipment
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NNCA Construction Workshop
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Exterior Insulated
Water Control:
Vapour Diffusion Control:
Plywood sheathing and/or sheathing
membrane
Air Control:
Drained/ventilated rainscreen
cladding with synthetic housewrap
WRB & surface of exterior insulation
Taped & sealed plywood or sealed
sheathing membrane
Cost/Constructability*:
Rigid insulation is expensive (high
shipping and labour handling costs)
Thicker insulation results in unique
wall penetration details & cladding
attachments
Split Insulated
Water Control:
Vapour Diffusion Control:
G.Finch - RDH
Poly/VB paint or plywood sheathing
Air Control:
Drained/ventilated rainscreen cladding
with synthetic housewrap WRB & surface
of exterior insulation
Taped & sealed plywood or sealed
sheathing membrane
Cost/Constructability*:
Rigid insulation is expensive (high
shipping and labour handling costs),
though less than all exterior insulated
Thicker insulation results in unique wall
penetration details & cladding
attachments
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How Much Insulation to get to R-40 Effective
Under Northern Design Conditions?
NOMINAL AND TEMPERATURE-DEPENDANT THERMAL
CONDUCTIVITIES FOR SELECT INSULATION MATERIALS
Nominal (24°C)
Cold Temperature (-20°C)
(R-value/inch)
(R-value/inch)
R-5
R-4
R-6.3
R-4.9
R-3.6
R-4.5
2 pcf Closed-cell Spray
Polyurethane Foam (ccSPF)
R-6
R-7.1
Polyisocyanurate (PIC)
Semi-Rigid Mineral Fibre (MW)
R-6?
R-4
R-3.5?
R-5.2
Dense-pack (4 pcf) Cellulose Fibre
Insulation (CFI)
R-3.6
R-4.3
Fibreglass Batt Insulation (FG)
R-3.6
R-4
Insulation Type
Extruded polystyrene (EPS)
Expanded polystyrene (XPS)
½ pcf Open-cell Spray Polyurethane
Foam (ocSPF)
Current test data for temperature dependent R-values only goes down as low as -20C.
Insulation Variables – Exterior Insulated
G.Finch - RDH
Effective R-value
@ Standard 24°C
Effective R-value
@ Cold -20°C
6.5” Extruded
polystyrene (XPS)
R-34
R-42
8” Expanded
polystyrene (EPS)
R-34
R-41
7.5” Rigid mineral
fiber (MFI)
R-32
R-41
9” Polyiso (PIC)
R-56
R-41
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NNCA Construction Workshop
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Safe Insulation Ratio for Split Insulated Walls?
RATIO OF EXTERIOR TO TOTAL INSULATION NOMINAL*
R-VALUE TO CONTROL AIR LEAKAGE CONDENSATION RISK
Indoor RH
Toutdoor (°C)
20%
30%
40%
50%
60%
0
0
0.12
0.32
0.47
0.60
-10
0.23
0.40
0.54
0.64
0.73
-20
0.41
0.55
0.65
0.73
0.80
-30
0.53
0.64
0.72
0.78
0.84
-40
0.66
0.70
0.76
0.82
0.86
*prudent to assess w/ temperature dependent insulation R-value
Insulation Variables – Split Insulated 2x4
Effective R-value
@ Standard 24°C
G.Finch - RDH
Effective R-value
@ Cold -20°C
5” Extruded
polystyrene (XPS) &
R-13 batt (FG)
R-37
R-43
6.5” Expanded
polystyrene (EPS) &
R-13 batt (FG)
R-38
R-43
6” Rigid mineral fiber
(MFI) & R-13 batt (FG)
R-36
R-43
7” Polyiso (PIC) & R-13
batt (FG)
R-54
R-42
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Insulation Variables – Split Insulated 2x6 (R-65+)
Effective R-value
@ Standard 24°C
Effective R-value
@ Cold -20°C
8” Extruded polystyrene
(XPS) & R-21 Batt (FG)
R-57
R-67
10” Expanded polystyrene
(EPS) & R-21 Batt (FG)
R-57
R-66
9.5” Rigid mineral fiber
(MFI) & R-21 Batt (FG)
R-55
R-66
11.5” Polyiso (PIC) &
R-21 Batt (FG)
R-86
R-67
Insulation Variables – Double Stud Walls/SIPs
Effective R-value
@ Standard 24°C
G.Finch - RDH
Effective R-value
@ Cold -20°C
13.5” Dense-packed
(4pcf) cellulose (CFI),
6.5” gap between 2x4s
R-38
R-41
13” Open-cell ½ pcf
sprayfoam (ocSPF), 6”
gap between 2x4s
R-37
R-40
5” Closed-cell 2 pcf
sprayfoam (ccSPF) and
7” Dense-packed (4pcf)
cellulose (CFI), 5” gap
between 2x4s
R-38
R-40
8” EPS SIPs
R-32
R-40
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Wall Thickness vs Effective R-value – R-40 walls
16
42
15
40
14
38
13
36
12
34
11
32
10
30
9
28
8
Wall Thickness (inches)
R-value at -20°C
Total Wall Thickness (without Cladding) and Effective R-value at -20°C - Sorted by Thickness
44
Hygrothermal Assessment
G.Finch - RDH
Hygrothermal modeling (WUFI)
performed for each wall
assembly using weather files
for 4 representative northern
territory cities
Wall modeled under “normal”
residential operating
conditions and also a realistic
scenario when wall exposed to
interior air leakage (from
defect in air-barrier)
Compared to baseline 2x6+
northern wall assembly as a
control
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Yellowknife Hygrothermal Assessment – Normal
Conditions
Sheathing Moisture Content (%)
16
All walls will perform
adequately under normal
operating conditions and
perfect air tightness, well
below 20% MC
14
12
10
8
6
4
2
0
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Control
Double-Stud Cellulose
Exterior Insulated with XPS
Split Insulated with XPS
Sep
Oct
Sep
Oct
Yellowknife Hygrothermal Assessment – with
Incidental Air Leakage
Sheathing Moisture Content (%)
60
Deep stud insulated walls with
cellulose or fiberglass are high
risk from any small air leaks–
ocSPF or ccSPF flash-and-fill
help reduce this risk
50
40
30
20
10
0
Oct
G.Finch - RDH
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Double-Stud Cellulose
Double-Stud Cellulose + Air Leak
Split Insulated with XPS
Split Insulated with XPS + Air Leak
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Hygrothermal Modeling Summary
Wall
C
1
2
3
4
5
6
7
8
9
10
11
12
HYGROTHERMAL DURABILITY SUMMARY
Hygrothermal
Wall ID
Notes
Assessment
Control
Fails by air leakage
Risky
D-CFI
Fails by air leakage
Risky
Spray foam insulation functions as
D-ocSPF
Pass
the air barrier and protects the
sheathing from direct air leakage.
Spray foam insulation functions as
D-ccSPF
Pass
the air barrier and protects the
sheathing from direct air leakage.
Locations for air leakage decay are
SIPS
Pass
at the joints between panels.
S4-EPS
Pass
Sheathing is above the dewpoint.
S4-XPS
Pass
Sheathing is above the dewpoint.
S4-MFI
Pass
Sheathing is above the dewpoint.
S4-PIC
Pass
Sheathing is above the dewpoint.
X-EPS
Pass
Sheathing is above the dewpoint.
X-XPS
Pass
Sheathing is above the dewpoint.
X-MFI
Pass
Sheathing is above the dewpoint.
X-PIC
Pass
Sheathing is above the dewpoint.
Materials & Resource Efficiency
G.Finch - RDH
Weights and volumes calculated for
all materials within each wall
assembly from drywall to
rainscreen strapping (no cladding)
Compression factors/weights
included for each of the insulation
types
Shipping of materials to different
regions estimated from local
contacts (including crating based
on volume & weight limits)
Construction costing analysis then
performed with local shipping,
material and labour rates
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Shipping Weight (lb/sq.ft of wall area)
14
1
0.9
12
0.8
10
0.7
0.6
8
0.5
6
0.4
0.3
4
0.2
2
0.1
0
0
Shipping Volume (cubic feet per sq.ft of wall)
Shipping Weights and Volume Comparison
Not including
cladding
Shipping Cost - $/sqft of Finished Wall Area
Relative Shipping Cost to Remote Regions – Resolute, NT
$4.50
$4.00
$3.50
$3.00
$2.50
$2.00
Sprayfoam (liquid in
drums) takes up little
space to ship vs
other insulations BUT
is expensive to install
once there
$1.50
$1.00
$0.50
$0.00
Not
including
cladding
G.Finch - RDH
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Total Consruction Cost per sq.ft of FInished Wall
Labour & Material Costs – Yellowknife
$25
$20
Labour
Material
$15
$10
$5
$0
Labour, Material and Shipping Costs - Resolute
Total Consruction Cost per sq.ft of FInished Wall
$60
$50
$40
Shipping
Labour
Material
$30
$20
$10
$0
G.Finch - RDH
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Total Wall Construction Cost per sq.ft of Finished Wall
Labour, Material and Shipping Costs – NT, NU, YT
$50
$45
Resolute Bay
Yellowknife
Whitehorse
$40
$35
$30
$25
$20
$15
$10
$5
$-
Cost Per Effective R-value – NT, NU, YT
Cost for Wall per Effective R-value at -20°C
$1.20
Resolute Bay
Yellowknife
Whitehorse
$1.00
$0.80
$0.60
$0.40
$0.20
$0.00
G.Finch - RDH
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Final Comparison & Weighted Score
NORTHERN R-40 WALL ASSEMBLIES SCORE CARD
Wall ID
Hygrothermal
Assessment
Thermal
Efficiency (10
is best)
Constructability
1
D-CFI
Risky
8
Moderate
9
22
2
D-ocSPF
Pass
9
Poor
4
15.5
3
D-ccSPF
Pass
6
Poor
5
13.5
Wall
Cost
(10 is
lowest)
Weighted
Score
4
SIPS
Pass
10
Specialized
7
22
5
S4-EPS
Pass
9
Excellent
10
27
6
S4-XPS
Pass
9
Excellent
9
27
7
S4-MFI
Pass
9
Excellent
8
25
8
S4-PIC
Pass
6
Good
7
20
9
X-EPS
Pass
10
Good
7
25
10
X-XPS
Pass
10
Good
8
24
11
X-MFI
Pass
10
Good
8
23
12
X-PIC
Pass
7
Good
6
19
Optimal R-40 Wall Design for the North
- XPS and EPS
insulation best choices
for new construction
- Rigid mineral wool
close 3rd
- With exterior insulation
ratio above 70%
discussed, no need for
poly VB at interior
(plywood & foam VB)
- Airtight sheathing or
sheathing membrane
G.Finch - RDH
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NNCA Construction Workshop
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Optimal Exterior Retrofit High R-value Wall
Design for the North
- In retrofit situations, better
practice is for vapour
permeable exterior insulation
(rigid mineral fiber) instead of
foam to avoid dual VB &
potential to trap moisture
And When You Can’t Decide Which – Both!
G.Finch - RDH
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NNCA Construction Workshop
2016-02-17
Case Study – R-40 Split Insulated Air-tight
Pre-fabricated Passive House Walls
Discussion + Questions
[email protected] – 604-873-1181
G.Finch - RDH
rdh.com | buildingsciencelabs.com
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