Insulating top of foundation wall

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jjkas
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Joined: Thu Jan 03, 2019 12:59 am

Insulating top of foundation wall

Post by jjkas » Thu Jan 03, 2019 10:56 am

I’m finishing a portion of my basement where the exterior wall is sitting on a ~3 ft foundation wall. I am framing a half wall to cover the cement foundation wall, that will transition as a shelf. I’ve insulated the concrete wall with rigid foam as seen below.
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My question is whether I should insulate the top of the foundation wall that sticks out from the sill plate. See below.
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My thought was to cut rigid foam to fit, (as seen below) then seal the crack in the corner with spray foam, and tape over that.
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Note that the house is 102 years old, and is definitely not tightly sealed, but I did a water test on the walls, and it is dry. Also, I live in Seattle, where it is very wet, but not particularly cold in winter or hot in summer. Thanks for any help you can provide.


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Shannon
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Re: Insulating top of foundation wall

Post by Shannon » Thu Jan 03, 2019 5:01 pm

Yes that will work very well for you. If you want you can also add bat insulation in the wall cavity for more R value as that thin foam does not give you much at all.
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jjkas
Posts: 2
Joined: Thu Jan 03, 2019 12:59 am

Re: Insulating top of foundation wall

Post by jjkas » Thu Jan 03, 2019 5:10 pm

I will put bat insulation in the short wall as well.
Thanks, I really appreciate the feedback, and all of your videos!

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