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Does spray insulation have to be covered?

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Posted by: from Laval Quebec
11/2/2015 at 11:48:39 AM

I am presently having my garage walls sprayed with insulation. My question is once the work is done, does it have to be covered or can it stay like that?

REPLIES (5)
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Date/Time11/2/2015 at 2:05:51 PM

You do not have to put any vapour barrier as spray foam acts as a vapour barrier and an insulator, unlike blown in insulation where with blown in insulation you must put a vapour barrier since blown in insulation is not solid like spray foam, just make sure it is the right type of spay foam insulation. Here at Arcamm Roofing, Insulation & Eavestrough we do our best to stay ahead of the market ensuring our customers get above and beyond building code to ensure we are at least meeting manufacturer's standards or better.

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Date/Time11/2/2015 at 5:39:56 PM

Hi Laval,

You don't have to cover it but it isn't a bad idea to do so. Depending on the product, it may discolour and/or attarct bugs or small rodents and by covering it, the issue is lessened. Also, if any area has been missed, the added vapour barrier will help. If it were me, I'd cover it (small added cost) and be done with it.

Regards from Alberta.

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Date/Time11/2/2015 at 10:43:22 PM

Cover it, Vapour barrier, drywall, plywood and finish. It will give you a better product and be code complying.

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Matthew from Matt of All Trades in Kitchener
Date/Time11/3/2015 at 7:50:15 AM

Check with your local authorities, but in Ontario spray foam must be covered as it is highly flammable. A vapor barrier is not required if greater than 2" in thickness.

If in your garage, some plywood is the best choice.

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Date/Time11/4/2015 at 10:01:39 AM

Hi there,

Matt above is correct about it being covered. Here in Ontario, yes it is required to be covered by Gypsum wallboard (drywall) because it is flammable.

The vapour barrier is a separate issue. There are generally two different types of spray foam, Open cell (also called Icynene) and closed cell. The closed cell has a higher R value or Resistance to Heat Transfer than the open cell and has a "Perm rating" that allows it to act as a vapour barrier, however, some municipalities may take issue (although rare, it does and has happened). There are some Inspectors that are concerned with the possibility of shrinkage of the wood framing materials over time as they reach equilibrium and are concerned that once the foam has cured (hardened) the shrinkage of the wood could cause slight gaps which would then become a direct thermal bridge, allowing the potential for condensation to form on the back of paper faced gypsum wall board.

Again this is uncommon as spray foam insulation is widely used now in the southern Ontario market.

To summarize, in Ontario, yes spray foam insulation is required to be covered with drywall.

If you use open cell spray foam, you require a vapour barrier of at least 6mil.

If you use closed cell spray foam, in most cases you do not require a polyethelene vapour barrier, but check with your Inspector first.

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