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Internal Insulation of Masonry Walls

I am renovating an Brick Home in Toronto. The exterior walls are Load bearing brick walls with some parging, furring, and plaster board. I want to add insulation on the interior using the wall assembly described on page 24 of the pdf guide "Internal Insulation of Masonry Walls: Final Measure Guideline" see below for URL. I have a question about this assembly... I noticed that there is no vapour retarder, should I install a vapour retarder on the warm side of the insulation between the insulation and the wood studs?

Also, would you recommend that I fully remove the existing furring and plaster board before added the new insulation assembly?


Thanks for any help.

Asked by david lam
Posted Jan 14, 2013 1:34 AM ET


1 Answer

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You'll notice that the experts at Building Science Corp. recommended the use of "semi-permeable rigid foam" -- for example, expanded polystyrene (EPS) -- for this detail. The reason that they specified semi-permeable foam is that it is desirable for this assembly to have some ability to dry to the interior. That's why you don't want to include an interior vapor barrier here. (The rigid foam is already a vapor retarder, but it isn't a vapor barrier.)

Whenever you insulate a multi-wythe brick building on the interior, it is essential to install the insulation directly against the bricks, with no intervening layers or air spaces.

For more information on these issues, see Insulating Old Brick Buildings.

Below is the detail under discussion.

Brick building with interior insulation.jpg
Answered by Martin Holladay, GBA Advisor
Posted Jan 14, 2013 8:57 AM ET

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