Spray Foam Depth in Renovated Basement?

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Posted by: from Calgary
6/14/2019 at 3:17:39 PM

I have a 1957 home in Calgary with an unfinished but apparently dry basement.

I had the framer in to put 2x6 walls up about 1" from the concrete and was going to add R22 fibreglass then 6mm poly then drywall.

Then I went to internet ...

So now, panicking about condensation and mold, I am considering spray foam against the concrete, then the fibreglass, then NO poly but just dry wall.

However, I am still worried that only 1 inch of closed cell spray foam will be cold enough the there will be condensation but now directly touching the fibreglass.

So, some options:

1) Replace fibreglass with rockwool - less susceptible to water but there may still be condensation

2) Spray foam out to 2 or more inches - expensive.

Is this is reasonable fear? I may be blowing this condensation risk way out of proportion but it is hard to tell.

Thanks for the advice.

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Date/Time6/15/2019 at 2:52:55 AM

Plain and simple answer to your question! There is nothing better than to lb spray foam insulation for your basement walls! You do not need a vapor barrier and you will never get mold penetration to the inside of your house for 25 years or more. A little bit more money that will save you money every day you own the house. Not to mention peace of mind that you did it right the first time!

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Matthew in Calgary
Date/Time6/15/2019 at 5:55:15 PM

Is 1 inch fine or should I do 2? Does it even matter?

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Date/Time6/16/2019 at 3:23:43 PM

2 inches of spray foam is typically considered a thermal break.

Therefore no poly is required as the spray foam itself replaces the need for poly.

Best way to go for sure. When you factor in the cost of batt insulation toward spray foam cost instead, it's well worth.

In fact, if you are that concerned about condensation, then this is the only route to consider.

Your condensation worries are justified but it depends on several factors. The proper install of batt, poly, acoustic seal etc being the biggest factor.

Best of luck....

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