Rigid foam on the outside of my house

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Posted by: from Calgary
2/21/2017 at 11:13:00 AM

Should I add rigid foam to the exterior of my house to get more R-value? I have 2x4 walls with vapor barrier. I was thinking of adding 2"-4" of rigid foam to try and get a R-value of R20-R30 including the insulation already in the walls.

I am worried about trapping moisture in the walls.

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Date/Time2/21/2017 at 1:09:09 PM

Yes, it is a good idea to insulate the outside of your house to increase your R-value. SM blue is the best Ridgid foam to use. If you're concerned about moisture the best way to beef up your R value is to sprayfoam from the inside.


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Date/Time2/21/2017 at 1:55:46 PM

Foam Board is a solution. Being that your home is framed with 2/4 the chances of the insulation in the walls being installed correctly is slim to none. Inspections on a Building Envelope didn't exist. Outside Stucco is a great look and provides a insulated exterior without creating a VapourBarrier. Just adding foam board to a exterior is not ensuring your home will be properly insulated. Attic venting are just some of the other areas to consider.

Good Luck!



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Date/Time2/21/2017 at 1:55:55 PM

I agree with jeff, 2" exterior with 2x4 interior sprayed foam for best results. If you do'nt want to demo interior 2" outside with new windows will beef up you R-value. Do air test prior and after completion for peace of mind.

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Yucel from CPM Group Inc. in TORONTO
Date/Time2/21/2017 at 7:22:29 PM

Adding rigid insulation is going to increase the R value of the building. Keep in mind there are other issues if the EPS is not installed correctly.

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Date/Time2/21/2017 at 8:12:08 PM

What is your exterior wall now ?

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Steve in Calgary
Date/Time2/21/2017 at 8:55:43 PM

Right now it is vinyl siding.

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