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Community and Q&A

Foundation insulation: fix it or forget it?

Tom Wheeler | Posted in General Questions on

Here is a picture of the corner of my catastrophe house that has the most water intrusion in the basement. 

I cleared out a significant amount of roots, and last summer we had a huge any colony coming inside here too. The water on the inside block starts at the top block and spreads from there. 

From the big picture picture, you can see I have no gutters, but I already moved the rocks that were the run off splash blocks that helped rot that log. 

I am getting gutters Friday,  and I am planning on doing solid corrugated pipe and even a bit of french drain since the topography is so crazy.  That should deal with most of the bulk water pretty well. 

But what should I do with this opening in the insulation?  Cut out the area in question and replace with sections on xps?  Spray foam the whole thing. Slap some tar on there?  

I was leaning towards a careful cutout of the corner, and measuring out 2 new pieces to fill the area. Then caulk with foam safe sealant at the joints. 

Or I could back fill and ignore. 

Standing water in close-up picture is from rinsing the area off. 

What do you think?

Northern Wisconsin zone 7


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  1. Expert Member
    Zephyr7 | | #1

    I think this is a perfect application for one of the little 12 board foot close cell spray foam kits. Submerge the cans in a bucket of warm water while you're using them to keep them warm and help maximize the amount of useful foam material you get. Make sure to clean the existing foam as well as you can so that the spray foam can adhere to it and make a good seal.

    Your new gutters will be a BIG help to keep the problem from recurring. Any grading you can do to help shed water away from the foundation will also help.


  2. Tom Wheeler | | #2

    I have some left from a prior interior application, so hopefully it will still be good. That just sounds too easy, can it be that easy??? I am leaning this way now. Thanks for your advice.

    Just wondering what the negatives to this option might be, other than cost of I had to buy new.

  3. Expert Member
    Zephyr7 | | #3

    The really small 12 board foot kits are under $50, as long as you don’t look online where they are usually sold in at least a two pack. It’s not the greenest option due to the material, but it’s probably the best option for what you’re trying to do.


  4. Expert Member
    Akos | | #4

    If you can get the foam cleaned up a bit, I would also tape the corner with some peel and stick. This way the corner will stay water tight even if the foam cracks down the road.

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