Best Method to Waterproof a Crawlspace

LESLIE: Len in Iowa, you’ve got The Money Pit. What can we do for you today?

LEN: Well, I have a crawlspace. Now, we’ve got a couple of real bad storms. A lot of rain. It hasn’t flooded over the years that I’ve had the house but with all this rain concentrated in a couple of days, it has collected water. And I’m wondering, what’s the best method to waterproof a crawlspace?

TOM: Well, I have fantastic news for you. Waterproof a crawlspace is a really easy project because you’ve told me all I need to know in mentioning that you generally have never had to waterproof a crawlspace before. But with all the heavy rain, you did develop one. Because this points clearly not to a rising water table, which could be complicated to fix, but it points directly to an issue with the gutters around your house and the grading. There’s too much water landing right around the foundation perimeter. That can happen if your gutters are blocked, if they’re too small or if the downspouts aren’t extended away from the house enough. They need to be, in your case, 4 to 6 feet away to make sure that that water is not doing a U-turn back into that crawlspace. On top of that, you should take a look at the grade. And if the soil is flat, if it’s sloped into the house, that’s another issue. You need to add clean fill dirt – which is good news, inexpensive – and you could slope it to drop about 4 inches – 4, 5, 6 inches – over 4 feet. It’s just about a 10-degree slope. Tamp it down real well but you have that nice slope maintained. And then on top of that, you could plant grass, you could put stone, whatever you want. But you’ve got to have that base soil sloped properly. And those two things will make this problem go away. It might take a while because it’s in the crawlspace but it will go away when you waterproof a crawlspace.

LEN: The house sits down from the road about – if you look from the elevation of the sidewalk, it sits off from the road about 8 foot. But as I said, I don’t have this problem generally. It’s pretty dry. I have it inspected every year for termites. And I asked the guys if it’s dry and they said, “Yes, it’s dry.” It’s only been a problem – you know, in Raleigh, we had the hurricane and then we had a lot of rain. This is why I need to waterproof a crawlspace.

TOM: Right.

LEN: So, I’m just trying to make sure that – I think the furnace sits on a cinder block – couple of cinder blocks up. It hasn’t – the water hasn’t reached the furnace, so it’s not like it’s a major problem.

TOM: Right. No. And I know that when this happens, people tend to want to speculate and calculate and like you’re saying, “Well, the road’s here and the house is there.” It’s really simple. If you get water in a basement or crawlspace after a heavy rain, it’s always the grading and the gutters. Always. There are no exceptions to that, OK?

LEN: OK.

TOM: So the solution is just to figure out what part of that is not working in your house, OK?

LEN: You think I should replace gutters with the …?

TOM: No. I think you should clean your gutters and I think you should extend the downspouts 4 to 6 feet away from the house so you don’t have any water coming off that roof that’s not drained those several feet from the house.

LESLIE: Going away from your property.

LEN: I got it. I got it.

TOM: OK?

LEN: OK. Yep. Thanks a lot.

TOM: Alright. Good luck.

LEN: Appreciate it.

TOM: Thanks so much for calling us at 1-888-MONEY-PIT.