Spray Foam Question

If I use spray foam inside my garage do I have to install a vapour barrier over it like ordinary insulation ? I'm in Canada, so I have no clue if the Ontario Building code says that you have to install a vapour barrier.
Thank you.
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Sir:
The reason for installing a vapor barrier is not related to code. If you want your insulation to stay free of moisture and remain an insulation a vapor barrier should be placed on the warm side of the insulation. If you are going to use air conditioning the requirement would be to place a vapor barrier on the walls and ceiling prior to placing the insulation. If you are planning to heat the area a vapor barrier and a flame barrier should be placed on the exposed insulation.

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Hate to break it to you but there is obviously a huge difference between cold storage and residential construction because that is flat out wrong.
Vapor barrier in a house goes on the warm side. The only place the vapor barrier goes up before the insulation is in the very far Southern US. In Canada it is ALWAYS on the inside under the drywall regardless of air conditioning.
Closed cell foams, such as Corbond, do not require a vapor barrier. Open cell, such as Icynene, do.
Steve.
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It depends on the type of foam used. Low density (open cell) foam requires a vapour barrier. High density, closed cell foam is completely air tight and waterproof, so it requires no other vapour barrier.

I am in Calgary, so I can't help you with Ontario code requirements. The companies that do foam insulation will know the local code requirements.
--
Murray Peterson


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Hey Murray:
Let's not lead this man astray. There is no closed cell spray foam. High density foam is not as high as one would think. It is used for exterior roof applications to prevent marring from foot traffic. There is no sprayed on foam insulation that does not require a vapor barrier. I have been in the Cold Storage Design and Contruction industry for 30 years and stay on top of my work. Please don't get this man in trouble with poor advice and have him replacing the insulation in a year or two.

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Art Yokell wrote:

Art,
I'm not saying you're wrong about sprayed in foam needing a vapor barrier, but can you provide some verification? The info I've come across tends to lead me to believe no vapor barrier is required (even building codes). Or, are you referring to specifically cold storage design?
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Strange -- the manufacturers of the foam products are asserting otherwise (including the ones that insulated the walls of my house). For example:
http://www.energsmart.com/images/Builder_0306.pdf
page 8-9 indicates that their product meets Canadian building standards for air infiltration, and no that additional vapour barrier is required.
--
Murray Peterson

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The on-line vendor of http://www.tigerfoam.com/ claims their insulation serves as a vapor barrier and needs no protection from fire. They also claim the R-value is superior to standard glass batt insulation, and that it is non-toxic. Maybe the cold storage guy should check this out and reply again...
Murray Peterson wrote:

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Well, sales literature like this has been around for years. Please note that none of the testing indicates no vapor barrier only the claims of the manufacturer. None of the companies mentioned are amongst the major spray foam suppliers of the world.
I have had the pleasure of either adding refrigeration equipment within a year of the initial installation or removing and replacing the insulation that has had moisture driven into it by the difference in vapor pressure created by the temperature difference. granted this may not be as pronounced in a residence but the facts are the facts.

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I think it's a bit more than just sales literature. My house walls are insulated with 2-lb SPF, and have no vapour barrier. Both the foam contractor and the building inspector believed that this fully met all Canadian (residential) building code requrements. I can't speak for refrigeration facilities -- that's a different kettle of fish entirely.
--
Murray Peterson

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Murray: I started out in my initial post saying the the vapor barrier has nothing to do with buidling codes. The fact that your house has no vapor barrier has no impact on the discussion. It will in my opinion take some time in a home for this to become noticable. However, you will slowly but surely be paying for the lack of a vapor barrier in higher heating or cooling bills.
As a final note I checked the Bayer site and found that they are in agreement with me. Bayer is the world's foremost producer of raw materials for foam systems and also produces some of the finest systems themselves. I am done with this nonsense!

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I don't know what's in the Canadian Building Codes, but it is certainly required here in the US (by building codes). And my guess is that they are also required by the CBC as well.
In the 2003 IRC, "Moisture Vapor Retarders" are required by Section 318 except for certain counties in the extreme southern states or where wall cavities have beed designed to allow for ventialtion of the moisture.
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Here is the "final word" as given by the Canadian National Research Council (NRC):
http://irc.nrc-cnrc.gc.ca/pubs/ctus/32_e.html
The report is detailed, but under the right circumstances (>40mm thicjness, no impermeable barrier on he cold side), they consider closed cell foams to be acceptable for vapour barrier in residences.
--
Murray Peterson

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Interesting read, thanks for posting. Have they adopted this into the NBC?
Anyone have a rough guess as to what the installed price of closed (such as Corbond) or open (Icynene) cell foam is going for (per sq. ft.)

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Murray, you were absolutely correct. Not only does the closed cell not require a vapor retarder, it should not be used at all, especially on the exerior side.

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I'm not familure with the Ontario Building code, but it's required everywhere here in the US [using the IRC] (except for certain warm counties in the extreme southern US, and where the cavity has been designed to ventilated to allow for moisture to escape. This would not be desirable in your neck of the woods.)
Keep in mind that the purpose is to prevent moisture-laden air from penetrating the exterior walls and (when it reaches the dew point inside the insulation) condensing into liquid water. (Moisture in air is measured as a pressure, and can (and will) push through any building product to equalize in dryer air. You need to protect not only insulation, but the studs as well. The entire wall needs to be protected.)
You may also run into other minor problems with spray foam, including protecting it from fire with a fire-protective barrier (all codes regulate when & where foam can be used, most either limit the thickness that can be used, and/or require 1/2" gypsum or concrete), and protection from termites (bugs love to burrow through it). The IRC requires a minimum of 6" clearance above ground level.
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