Interior concrete wall paint / Drylok

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pshep123
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Joined: Thu Aug 08, 2019 6:32 pm

Interior concrete wall paint / Drylok

Post by pshep123 » Mon Oct 28, 2019 6:56 pm

My basement walls are cinder block, some above and some below grade. I live in upstate New York (average January high is below freezing) but the walls are not insulated at all. I plan on putting 2" rigid foam directly on the walls then a 2x4 stud wall inside that with batt insulation, but my question is actually around waterproofing.

I've seen a lot of people recommend Drylock or other "waterproofing" paint applied directly to the concrete wall, both above and below grade. However, this seems to me that if any moisture is getting through the wall, trapping it with paint could cause a serious foundation issues during freeze-thaw cycles.

I realize any moisture should be stopped from the outside, but that's not a project I'll be able to handle prior to this coming winter.

So my questions are:

1. Are there any downsides to a Drylok type of paint?
2. Does rigid foam act as a moisture barrier anyway?
3. Does the insulation of the wall / Drylok differ based on being above / below grade?

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Aaron
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Location: St. Paul, MN

Re: Interior concrete wall paint / Drylok

Post by Aaron » Tue Oct 29, 2019 6:27 am

Like you, I don't really understand the practical purpose of Drylok. I personally wouldn't trust the waterproofing of my basement to a membrane of paint.

Honestly I would wait until next Spring when you can address all the things you need to do outside to correct any water intrusion issues you have and take the necessary steps to rememdy those the sound and traditional ways, such as grading a slope away from the house, installing gutters, etc.

A more expensive permanent solution would be to dig a trench around the house and apply a thick poly shield stuck with tar around the base of the house. Of course that is a pretty big expensive project but long term it is an effective solution.

Once you're confident you have a bone dry basement, then I would proceed with finishing it.

pshep123
Posts: 15
Joined: Thu Aug 08, 2019 6:32 pm

Re: Interior concrete wall paint / Drylok

Post by pshep123 » Tue Oct 29, 2019 6:53 am

I had a feeling that's the advice I'd get, and also glad to hear my thinking on Drylok isn't off-base.

That said, I just don't want to deal with 4 months of winter without some kind of insulation. Good news is that the west side of the basement is mostly above grade and the ground naturally slopes toward the west. I don't think there is much (if any) water intrusion on that side, so I feel pretty confident I can insulate at least one wall.

The east side is completely below grade may have water intrusion issues, but I think could be warmer due to deep soil (well below the frost line) and it's the side that is far less exposed to cold winter winds.

Thanks for your help Aaron.

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Shannon
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Re: Interior concrete wall paint / Drylok

Post by Shannon » Tue Oct 29, 2019 7:46 am

If you don't have leaking basement walls then you should have no issues. Slight moisture is not usually a problem and the rigid foam does act as the moisture barrier. Those paint products I would not even waste my $$ on.
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pshep123
Posts: 15
Joined: Thu Aug 08, 2019 6:32 pm

Re: Interior concrete wall paint / Drylok

Post by pshep123 » Tue Oct 29, 2019 8:07 am

Alright, that settles it, no Drylock.

Thanks Shannon.

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