air barriers & vapour barriers spuf vapor... · 2006-03-20 · vapour barriers, air barriers...
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Dr John Straube University of Waterloo
BalancedSolutions.com 1
Vapour Barriers, Air Barriers
andThe CUFCA Vapour Barrier Study
CUFCA FoamDays'06 University of Waterloo BEG 2
Outline
� In 1.5 hours� Background on water vapor in air� Air Barriers vs Vapor Barriers� Vapor Barrier History� CUFCA Experiment
CUFCA FoamDays'06 University of Waterloo BEG 3
Air Barriers & Vapour Barriers
�� Air Barriers Control Air LeakageAir Barriers Control Air Leakage� Heat (for comfort & energy considerations)� Smoke & odours� Sound� Moisture
�� Vapour Barriers Control Vapour DiffusionVapour Barriers Control Vapour Diffusion� Moisture
CUFCA FoamDays'06 University of Waterloo BEG 4
SPUF
� Spray applied (continuous) product that� Provides insulation (high R/inch)� Provides vapor resistance (varies)� Provides an air barrier� Stops convection� Some provide a drainage surface for rainwater
� All of these features and function inter-relate!
Dr John Straube University of Waterloo
BalancedSolutions.com 2
The Backround
Vapour in Air
CUFCA FoamDays'06 University of Waterloo BEG 6
The 4 phases of Water
GasGas(water vapour,
steam)
frost
sublimateevaporate
condense
freeze
thaw
desorbadsorb
Adsorbed
Liquid(water)
Solid(ice)
Air Barriers &Vapour Barriers
only deal with theVapour PhaseVapour Phase
CUFCA FoamDays'06 University of Waterloo BEG 7
Water Vapour Pressure
CUFCA FoamDays'06 University of Waterloo BEG 8
Water Vapour Pressure
� For water vapour in a container� Higher temperature =
� more energy� higher velocity� harder collisions with wall (higher pressure)
� Greater number of molecules =� more collisions with walls (higher pressure)� pressure simply another measure for moisture content
Dr John Straube University of Waterloo
BalancedSolutions.com 3
CUFCA FoamDays'06 University of Waterloo BEG 9
Water Vapour in Air
� Water vapour exists in all air� Air has a maximum vapour holding capacity
� This capacity changes dramatically withtemperature
� When the maximum holding capacity isexceeded, condensation occurs
� These facts are summarized by thepsychrometricpsychrometric chart
CUFCA FoamDays'06 University of Waterloo BEG 10
CUFCA FoamDays'06 University of Waterloo BEG 11-10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
Temperature (°C)
0
500
1000
1500
2000
2500
3000
3500
4000
Vap
ou
r P
ress
ure
(P
a)
100% RH75% RH50% RH25% RH
Psych Chart: Air Vapour Content vs Temperature
Saturation
50%
RH
25%RH
75%
RH
100%
RH
100%RH
Temperature
Air
Moi
stur
e C
onte
nt
=va
pour
pres
sure
(Pa,
in H
g),
hum
idity
rat
io (g
/kg,
gra
ins/p
d)
-10 ºC14 º F
0 ºC32 º F
10 ºC50 º F
20 ºC68 º F
30 ºC86 º F
40 ºC104º F CUFCA FoamDays'06 University of Waterloo BEG 12
Methods to get Condensation
Dr John Straube University of Waterloo
BalancedSolutions.com 4
CUFCA FoamDays'06 University of Waterloo BEG 13
Condensation by cooling:Cool air can hold less vaporInsulation influences material temps
Cool air – increase RHHeat air – decrease RH
Vapor Movement
CUFCA FoamDays'06 University of Waterloo BEG 15
Water Vapour Transport
�Vapour Diffusion (like heat conduction)
� more to less vapour
�Air Convection (like heat convection)
� more to less air pressure� vapour is along for the ride
CUFCA FoamDays'06 University of Waterloo BEG 16
Vapour Diffusion
� Movement from moremore vapour to lessless� Slow process� Many materials slow this process
� concrete, brick, stone� Some stop, or practically stop it
� many plastics (poly), steel, glass� May provide supply of vapour need to
support condensation (but not often)
Dr John Straube University of Waterloo
BalancedSolutions.com 5
CUFCA FoamDays'06 University of Waterloo BEG 17
-10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
Temperature (°C)
0
500
1000
1500
2000
2500
3000
3500
4000
Va
po
ur
Pre
ssure
(P
a)
100% RH75% RH50% RH25% RH
Indoor Conditions
• 18 - 26°C / 65 – 78°F• 25 to 60%RH(Could be 20 to 70%)
Summer
Winter
-10 ºC14 º F
0 ºC32 º F
10 ºC50 º F
20 ºC68 º F
30 ºC86 º F
40 ºC104º F CUFCA FoamDays'06 University of Waterloo BEG 18
-10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
Temperature (°C)
0
500
1000
1500
2000
2500
3000
3500
4000
Vap
ou
r P
ress
ure
(P
a)
100% RH75% RH50% RH25% RH
Outdoor ConditionsOutdoor Conditions:WaterlooJanuary -7°C / 80%July 20°C / 75%WinnipegJanuary –19°C / 80%July 20°C / 70%
-10 ºC14 º F
0 ºC32 º F
10 ºC50 º F
20 ºC68 º F
30 ºC86 º F
40 ºC104º F
CUFCA FoamDays'06 University of Waterloo BEG 19-10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
Temperature (°C)
0
500
1000
1500
2000
2500
3000
3500
4000
Vap
ou
r P
ress
ure
(P
a)
100% RH75% RH50% RH25% RH
Indoor vs Outdoor Conditions
Summer
Winter
VapourPressureDifference
-10 ºC14 º F
0 ºC32 º F
10 ºC50 º F
20 ºC68 º F
30 ºC86 º F
40 ºC104º F CUFCA FoamDays'06 University of Waterloo BEG 20
MoreVapour
LessVapour
Cold weatherCold weather
VapourVapourDiffusionDiffusion
Warm humid weatherWarm humid weather
MoreVapour
CondensationCondensation
Cold Surface
Water Vapour Diffusion
Dr John Straube University of Waterloo
BalancedSolutions.com 6
CUFCA FoamDays'06 University of Waterloo BEG 2150 F 68 F32 F CUFCA FoamDays'06 University of Waterloo BEG 22
CUFCA FoamDays'06 University of Waterloo BEG 23 CUFCA FoamDays'06 University of Waterloo BEG 24
Dr John Straube University of Waterloo
BalancedSolutions.com 7
CUFCA FoamDays'06 University of Waterloo BEG 25 CUFCA FoamDays'06 University of Waterloo BEG 26
CUFCA FoamDays'06 University of Waterloo BEG 27 CUFCA FoamDays'06 University of Waterloo BEG 28
Vapour Retarders
� Vapour retarders are needed to
control vapour diffusioncontrol vapour diffusion� Don’t need be continuous – small tears and openings OK
� Usually placed near the warm side of the wall or roof --near the inside in our climates
� Semi-permeable barriers allow more design flexibility(and more drying)
Dr John Straube University of Waterloo
BalancedSolutions.com 8
CUFCA FoamDays'06 University of Waterloo BEG 29
Vapour Barriers
�Vapour barriers in Code: <1 US perm� based on Rowley 1937� no good science
�Vapour retarder approx 2-5 US perm�Measurement Units
�� MetricMetric perms ng /(s·m2·Pa)�� USUS perm grain/(hr·in Hg· ft2)� WVT grams/(sq ft/24 hours)
CUFCA FoamDays'06 University of Waterloo BEG 30
Vapour Retarders
� Inner permeance usually should be less than outer incold climates with few hot humid hours� E.g. unvented metal cladding, use low perm inside
� Walls with insulated sheathing do not need as muchinner resistance� e.g., low perm paint works well in this case
� Too low inner permeance resists drying, promotessummer condensation� e.g., polyethylene is often too much
CUFCA FoamDays'06 University of Waterloo BEG 31
Low-perm Materials (<1/60)
� 6 mil Poly 0.1 US perm (5.7 metric)
� Vinyl wall paper 0.3 perm (17.1)
� 8” Conc. Fdn. wall 1/2 perm (28.5)
� Drywall with a VB paint 0.1 to 1 perm (5.7- 57)
� Brick veneer 1/2 - 2 perms (28.5-57)
� Extruded foam 1/2 - 1 for 1.5” (28.5-85.5)
� Plywood 0.5 to 20 (dry to wet) (28.5-1140)
� Kraft paper 0.3 to 2 (dry and wet) (17.1-114)CUFCA FoamDays'06 University of Waterloo BEG 32
Mid-perm Materials (1-10)
� Plywood 0.5 to 20 (dry to wet) (28 -1100)
� Expanded polystyrene foam 2.5 - 5 permsfor 1 inch (150-300)
� Spray PUR about 1-2 perms/inch (60-120)
� Drywall with latex paint (2-8 perms) (120-500)
Dr John Straube University of Waterloo
BalancedSolutions.com 9
CUFCA FoamDays'06 University of Waterloo BEG 33
High-perm Materials (>10/600)
� Fibreboard over 20 (>1100)
� Plywood 0.5 to 20 (dry to wet) (30-1100)
� Icynene open cell spray foam 10-13 (500-750)
� Tyvek other housewraps20 to 50 perms (1100-2800)
� Building paper over 5 to 20 (250-1200)
CUFCA FoamDays'06 University of Waterloo BEG 34
Vapour Permeance: Sheathing
0
500
1000
1500
2000
2500
0 0.2 0.4 0.6 0.8 1
Relative Humidity
Perm
eanc
e (n
g/P
a s
m2) 11.1 mm OSB
12.7 mm Plywood
Dry
Cup
Wet
Cup
CUFCA FoamDays'06 University of Waterloo BEG 35
In the beginning
• Find the vapour barrier
CUFCA FoamDays'06 University of Waterloo BEG 36
Old Assemblies
� Integral vapour resistance� Massive moisture storage
MasonryMasonry
PlasterPlaster
NoNo vapourvapourbarrier of coursebarrier of course
Dr John Straube University of Waterloo
BalancedSolutions.com 10
CUFCA FoamDays'06 University of Waterloo BEG 37
Old Framed Assemblies
� Little to some vapour resistance� Little moisture storage� Little insulation / air leaky = dry!
tt
NoNo vapourvapourbarrier of coursebarrier of course
CUFCA FoamDays'06 University of Waterloo BEG 38
Changes . . .
� Increase in wood frame, esp. post WW1� Began to add insulation
� comfort� wood scarcity, coal
� Moisture problems in cold climatesnoted in 1930’s
� Paint peeling of siding
tt
CUFCA FoamDays'06 University of Waterloo BEG 39
Dr Frank Rowley
� Professor of Mechanical Engineering atUniversity of Minnesota
� ASH&VE 1932 president� Proponent of using heat flow analogy for
vapor flow in calculations� Conducted full scale house in climate chamber
studies –paid for by insulation companies
CUFCA FoamDays'06 University of Waterloo BEG 40
The One US Perm
� “Test house” inside climate chamber
--29 C/29 C/--20 F20 F
21 C/ 70 F40% RH
No VB:No VB:21.5 g/m21.5 g/m22/day/day(0.07 ounce/ft(0.07 ounce/ft22/day)/day)
This research resulted in 1 perm / 60ng/Pa s m2 or less vapor barriers
ASH&VE Transactions No 44,“Condensation Within Walls”1938
Dr John Straube University of Waterloo
BalancedSolutions.com 11
CUFCA FoamDays'06 University of Waterloo BEG 41
Air barriers discovered
� Air leakage identified by : “The rate ofcondensation is about ten times that at which vapourmight be expected to diffuse through …It seemsnecessary to assume some other mechanism … theleakage of warm moist air outward ..” Neal Hutcheon,1950
� Solution suggested by many:� Why not use the vapour barrier
� Add “sealed” or “continuous” to codes language� Air barriers spelled out in 1985 NBCC
CUFCA FoamDays'06 University of Waterloo BEG 42
When and where
� Choice of vapour permeance and location ofvapor barrier depends on� Exterior Climate� Interior Climate� Wall Assembly
�Any “rule” that does not considerthese factors cannot provide correctguidance
CUFCA FoamDays'06 University of Waterloo BEG 43
When and Where
� Place on warm side of enclosure� summer and winter balance
� If you use a VB on cold side of wall -ventilate!
� If extreme temps/RH, use VB� If moderate, use VR (retarder, like paint)� Insulated sheathing changes everything� If in doubt - figure it out� Climate is one guide
CUFCA FoamDays'06 University of Waterloo BEG 44
Cold
Severe Cold
Hot-Dry
Mixed-Humid
Dr John Straube University of Waterloo
BalancedSolutions.com 12
CUFCA FoamDays'06 University of Waterloo BEG 45
Climate and VB
� Florida is hot and humid� moisture is outdoors� place VB near outside� allow vapour to flow INWARD
� Winnipeg/Bismark is cold/dry� bitterly cold winters� summers are hot and dry� place VB near inside� allow vapour to flow outward
CUFCA FoamDays'06 University of Waterloo BEG 46
Climate and VB
� Vancouver� moisture is both indoors outdoors� allow vapour to flow inward and outward� use VR near inside (paint)
� Toronto� summers are hot and humid, winters cold� if rain-wetted cladding, inward is important!� allow vapour to flow inward and outward� use VR near inside (paint) or exterior insulation
CUFCA FoamDays'06 University of Waterloo BEG 47
VB and Wall design
� Likely need vapour barriers:� low integral vapour resistance
� framed walls with batt� Rarely need VB:
� Integral vapour resistance� SIPS� spray foam
� Built in VB� concrete
� Kept warm� insulating sheathing
CUFCA FoamDays'06 University of Waterloo BEG 48
Foam Insulation outside block
� Works everywherewithout calculation
Courtesy: Joe Lstiburek
Dr John Straube University of Waterloo
BalancedSolutions.com 13
CUFCA FoamDays'06 University of Waterloo BEG 49
Wall permeable insulation, no VR
Vapour Diffusionin faster than flowout
Cold =Cold =CondensationCondensation
Sheathing Vapour PermeableInsulation and finish
CUFCA FoamDays'06 University of Waterloo BEG 50
Semi-permeable insulation, no VR
VapourDiffusion inslowed to matchflow out
Cold but NOCondensation
Sheathing Vapour Semi-Permeable Insulation
CUFCA FoamDays'06 University of Waterloo BEG 51
Drying
� Vapour barriers stop wetting andand drying� Overkill (e.g. poly) can cause problems!� Inward drying is useful in many climates
CUFCA FoamDays'06 University of Waterloo BEG 52
Summary for Vapour Barriers
� Vapour flows from moremore to lessless� It goes bothboth ways (In-Out & Out-In)
� Vapour Barriers do notdo not need to be continuous�� DonDon’’tt always need a separate vapour barrier
many walls have integral resistance� Be careful to allow drying
�� Vapour Barrier = Drying RetarderVapour Barrier = Drying Retarder
Dr John Straube University of Waterloo
BalancedSolutions.com 14
Back to Air Barriers
A strong, continuous, durable, stiff airimpermeable layer must be provided to
stop uncontrolled airflow in allbuilding enclosures.
CUFCA FoamDays'06 University of Waterloo BEG 54
Remember
�� Vapour Barriers Control Vapour DiffusionVapour Barriers Control Vapour Diffusion� Why? 1. Wetting and drying
�� Air Barriers Control Air LeakageAir Barriers Control Air Leakage� Why control air leakage? Six reasons.� Heat (for 1. comfort & 2. energy considerations)� 3. Fire & Smoke & 4. odours� 5. Moisture� 6. Sound
CUFCA FoamDays'06 University of Waterloo BEG 55
Why Air Barriers for Moisture?
�� Air leakageAir leakage moves moistmoist air (vapourvapour)through the assembly to locations where itcan condense
� Two air leakage concerns for moisture:1. Through Wall2. Wind Washing Air Barrier
CUFCA FoamDays'06 University of Waterloo BEG 56
Condensation: Cool air containsless vapor
Cool air – increase RHHeat air – decrease RH
Dr John Straube University of Waterloo
BalancedSolutions.com 15
CUFCA FoamDays'06 University of Waterloo BEG 57
Air leakage vsDiffusion
� Air leakage is much morecritical
� Walls sensitive todiffusion-relatedcondensation will be moresensitive to air leakage
CUFCA FoamDays'06 University of Waterloo BEG 58
Airleakage
CUFCA FoamDays'06 University of Waterloo BEG 59
Diffusion
CUFCA FoamDays'06 University of Waterloo BEG 60-10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
Temperature (°C)
0
500
1000
1500
2000
2500
3000
3500
4000
Vap
ou
r P
ress
ure
(P
a)
100% RH75% RH50% RH25% RH
Air Leakage vs Diffusion
Summer
Winter
Air LeakageCondensation
Diffusion
1. Air leakage occurs at higheroutdoor temp than diffusion
2. Air leakage results in a muchgreater rate of condensation
Dr John Straube University of Waterloo
BalancedSolutions.com 16
CUFCA FoamDays'06 University of Waterloo BEG 61
Glass is a perfect VB but …tiny cracks
CUFCA FoamDays'06 University of Waterloo BEG 62
Bigger cracks =more condensation
CUFCA FoamDays'06 University of Waterloo BEG 63
Air Leakage & Condensation
�� DamagingDamaging airflow direction is:� cold weather inside to outsideinside to outside� warm weather outside to insideoutside to inside
� Condensation can ONLYONLY occur if both:� air contacts a cold surface (no ABS), andand� air flow is in the direction of more to less vapour
(driving forces)
CUFCA FoamDays'06 University of Waterloo BEG 64
Driving Forces
Wind Effect Stack Effect Combustion and Ventilation
Dr John Straube University of Waterloo
BalancedSolutions.com 17
CUFCA FoamDays'06 University of Waterloo BEG 65
Controlling Air LeakageCondensation
1. Stop all airflow2. Control driving forces
(HVAC/ air pressures)3. Control Temperature
of condensing surface4. Reduce interior
moisture load
CUFCA FoamDays'06 University of Waterloo BEG 66
Air leakage (Convection)
MorePressure
LessPressure
Cold WeatherCold Weather
AirAirLeakageLeakage
Warm WeatherWarm Weather
MorePressure CondensationCondensation
if T < Dewpointif T < Dewpoint
Cold Surface
CUFCA FoamDays'06 University of Waterloo BEG 67
Airflow Control: Where
� Stop airflow = stop many problems= Air BarrierAir Barrier= SPUF= SPUF
�Can locate anywhere in enclosure� Important in all climates, and all interior
conditions�The more extreme, the more important
CUFCA FoamDays'06 University of Waterloo BEG 68
� Air barrier systems are required to stopstopairflow through enclosureairflow through enclosure
� ABS can be placed anywhere in the enclosure� Must be strong enough to take wind gusts
� Air barrier systems must be continuouscontinuousThey leak at joints, interfaces, penetrationsjoints, interfaces, penetrations
� multiple air barrier planes are useful forredundancy
Air Barriers are Systems(not materials)
Dr John Straube University of Waterloo
BalancedSolutions.com 18
CUFCA FoamDays'06 University of Waterloo BEG 69
Air Barrier Systems Summary
� Buildings leak at joints, interfaces, penetrationsjoints, interfaces, penetrations� Hence
� “The air permeance of materials used is less importantthan continuity of the system”
� Air permeance of wall/roof etc should be low� Suggest less than about 0.2 lps/m2@75 Pa, usually better� Any material that allows this is OK, even if >0.02 lps
required by CCMC
CUFCA FoamDays'06 University of Waterloo BEG 70
Air Barrier System Requirements
� Continuous� primary need
� Strong� designed for full wind load
� Durable� critical component - repair, replacement
� Stiff� control billowing, pumping
� Air Impermeable� (may be vapour permeable)
CUFCA FoamDays'06 University of Waterloo BEG 71Typical Air Leakage Points CUFCA FoamDays'06 University of Waterloo BEG 72
Big Air LeakagePoints
Dr John Straube University of Waterloo
BalancedSolutions.com 19
CUFCA FoamDays'06 University of Waterloo BEG 73
Big Air LeakagePoints
CUFCA FoamDays'06 University of Waterloo BEG 74
Why was a poly sheet added to the interior?
A wonderful air barrier system ifjoints sealed too.
CUFCA FoamDays'06 University of Waterloo BEG 75
Sealed poly is a mediocreair barrier system
CUFCA FoamDays'06 University of Waterloo BEG 76
Air sealingaroundwindows andotheropenings
Dr John Straube University of Waterloo
BalancedSolutions.com 20
CUFCA FoamDays'06 University of Waterloo BEG 77
Cracks and OpeningsCracks and Openings
CUFCA FoamDays'06 University of Waterloo BEG 78
Internal Moisture Loads
� Important for cold climate use of 0.5 pcf SPUF!Primary load for vapour diffusion and air leakage
condensation� More unknown (!) than exterior� Temperature
� 8 to 76 F (21 to 26 )
� Relative Humidity� 20 to 75% ?
CUFCA FoamDays'06 University of Waterloo BEG 79-10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
Temperature (°C)
0
500
1000
1500
2000
2500
3000
3500
4000
Vap
ou
r P
ress
ure
(P
a)
100% RH75% RH50% RH25% RH
Air Leakage vs Diffusion
Summer
Winter
Air LeakageCondensation at High
Interior Moisture
Condensation at LowInterior Moisture
Reduce moisture loads= reduced condensation
CUFCA FoamDays'06 University of Waterloo BEG 80
Control Interior RH!
Canadian Climate� Exhaust ventilation
� $150 + operating� Air-to-Air Heat
exchanger� $1000 + operating
Dr John Straube University of Waterloo
BalancedSolutions.com 21
CUFCA FoamDays'06 University of Waterloo BEG 81
Air Barrier Systems Summary
� Air barrier systems are required tostop uncontrolled airflowstop uncontrolled airflow
� ABS can be placed anywhere in the enclosure� Must be strongstrong enough to take wind gusts� Must be continuouscontinuous� Must be durabledurable� Should be stiffstiff enough not flap around
The CUFCA Study
CUFCA FoamDays'06 University of Waterloo BEG 83
Objectives
� Answer“When and where do I need a vapor barrier?”
� Provide Scientific, third-party, openinformation
CUFCA FoamDays'06 University of Waterloo BEG 84
Approach
� Full-scale field measurements of real walls� Laboratory Climate Chambers of different
types of foams� Computer modeling of different climates
Dr John Straube University of Waterloo
BalancedSolutions.com 22
CUFCA FoamDays'06 University of Waterloo BEG 85
Walls
� Four different types� ½ pcf wood frame� 2 pcf wood frame ( types)� 2 pcf exterior spray, steel studs
� Pair of each installed: north and south facing
CUFCA FoamDays'06 University of Waterloo BEG 86
Walls #6/7:two densities no poly
CUFCA FoamDays'06 University of Waterloo BEG 87
Walls#8/9:high-density, commercial/residential
CUFCA FoamDays'06 University of Waterloo BEG 88
The Beghut
Dr John Straube University of Waterloo
BalancedSolutions.com 23
CUFCA FoamDays'06 University of Waterloo BEG 89 CUFCA FoamDays'06 University of Waterloo BEG 90
Sensor Package
� Within walls� Temp, RH, MC
� Interior and Weather conditions:� Temp, RH, sun, rain, wind,
� Every 5 minutes, saved hourly
CUFCA FoamDays'06 University of Waterloo BEG 91 CUFCA FoamDays'06 University of Waterloo BEG 92
Dr John Straube University of Waterloo
BalancedSolutions.com 24
CUFCA FoamDays'06 University of Waterloo BEG 93 CUFCA FoamDays'06 University of Waterloo BEG 94
CUFCA FoamDays'06 University of Waterloo BEG 95
Environmental Conditions
� Interior� Warm (21 C) and very humid (50%)
� Exterior� Cool 4650 DD, design temp -21 C
� Computer modeling allows us to extrapolateto other conditions – colder, warmer, drier
CUFCA FoamDays'06 University of Waterloo BEG 96-20
-15
-10
-5
0
5
10
15
20
25
2005/11/1100:00
2005/11/1900:00
2005/11/2700:00
2005/12/0500:00
2005/12/1300:00
2005/12/2100:00
2005/12/2900:00
2006/01/0600:00
2006/01/1400:00
2006/01/2200:00
Tem
pera
ture
(C)
Ext TempInt DewPointInterior Temp
Exterior and Interior Conditions
Dr John Straube University of Waterloo
BalancedSolutions.com 25
CUFCA FoamDays'06 University of Waterloo BEG 97
0
5
10
15
20
25
2005
/11/11
2005
/11/18
2005
/11/25
2005
/12/02
2005
/12/09
2005
/12/16
2005
/12/23
2005
/12/30
2006
/01/06
2006
/01/13
2006
/01/20
OSB
She
athi
ng M
oist
ure
Con
tent
(w%
)
N6 (0.5 pcf) N7 (2 pcf) N8 (2 pcf)
S6 (0.5 pcf) S7 (2 pcf) S8 (2 pcf)
OSB moisture Content to end of January
CUFCA FoamDays'06 University of Waterloo BEG 98
Preliminary Results
� Performance as expected� 2 pcf closed cell foam controls vapor flow even
in challenging conditions� ½ pcf foam requires consideration – in high
humidity conditions may need paint layer
CUFCA FoamDays'06 University of Waterloo BEG 99
Future
� Climate chamber� 14 or more combinations of foam, and poly� Run at for a few weeks at large temperature and
humidity differences� Computer model
� Show that they work� Extend results to different climates/conditions
CUFCA FoamDays'06 University of Waterloo BEG 100
Conclusions
� Existing vapor barrier rules are based onlittle science and often wrong
� SPUF can provide an excellent air barriersystem� This is more important to moisture control than
vapor barriers� Closed cell SPUF does not require special
VB layer, certainly not poly!� ½ pcf SPUF may need vapor control in some
cases
Dr John Straube University of Waterloo
BalancedSolutions.com 26
CUFCA FoamDays'06 University of Waterloo BEG 101
Website
� University of Waterloo
BBuilding EEngineering GGroupwww.civil.uwaterloo.ca/beg
Building Science Textbook atwww.johnstraube.ca
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