How Effective is Waterproofing Paint for the Basement?

LESLIE: Next up is Evelyn in Minnesota who listens to The Money Pit on KNUJ and you want to talk about waterproofing the basement.

So how can we help?

EVELYN: Hi. Yeah. Our son recently bought a house and there is not a huge moisture problem; just a small problem which he is trying to take care of with landscaping and so on. But the question mostly is, is the waterproofing paint that you put on the inside on the block walls, is that really a good idea or are you sealing a moisture problem behind it that you might not see if the water is still trying to come in. So basically, is it a good idea or isn’t it?

TOM: That’s an excellent question and I would say that waterproofing paint, or the so-called waterproofing paint, it’s not really waterproofing paint because if you have a water problem it’s still going to find its way through. But that is a good part of an overall water management solution to a damp or a wet basement.

It starts outside, right where your son is working, by taking a look at the outside drainage conditions. The gutter system and the grading are both important. The grading has to slope away from the wall. It can’t have a lot of materials used in it that absorb water. Like topsoil, for example, would be a bad thing to put around a house that has a drainage problem or a wet basement because it’s just going to hold a lot of water. You want to use clean fill dirt. And then looking at the gutter system is even more important because you want to make sure the gutter system is clean and free-flowing and that all the downspouts discharge away.

So if you did those two things and you really got the water managed right on the outside, Evelyn, then like the last step is maybe to paint the walls with a waterproofing paint. Because what that’s going to do is that’s going to stop the evaporation of moisture that remains in the concrete walls into the basement. It’ll slow down that evaporation. So certainly it’s part of it but it should be done last, not first.

EVELYN: OK. That makes sense. Yes. Well, OK. I think that answers my question wonderfully. Thank you so much.