Grading and Drainage to Help a Wet Basement
LESLIE: Taking a call from Joe in New Jersey regarding his basement. What’s going on?
JOE: Hi. I’m trying to waterproof my basement. I have the cylinder block walls and I purchased Behr paint specifically for the walls. But on the floor in the corners I have a gap; about a two-inch gap between the cylinder walls and the actual cement floor. And I really want to waterproof it so what can I do to either plug that up with some maybe cork or something?
TOM: Well (clears throat), first of all, buying the Behr basement masonry paint was a good thing because that, when you place it on the walls, is going to stop that soil evaporation where the water gets – collects on the outside and evaporates and eventually leaks into the basement. But there’s a couple of other things that you should be doing outside to improve the grading and the drainage so that you reduce the volume of water that gets there in the first place.
LESLIE: Yeah, you really want to look at the outside of your house, Joe, before you even think about the inside. Number one, you want to make sure that there are gutters, you know, and sufficient amount of gutters and downspouts all along your house’s roof line. You want to make sure that if you’ve got those gutters that they’re clean; that the downspouts are free-flowing. You know, really take the time to clean out these gutters a couple of times a year and if you don’t feel like doing it yourself you can hire a service to come and do it quarterly or go ahead and put some sort of guard cover on top. The ones that sort of flap over the entire top of the gutter are a lot better than the screen-like ones, which tend to just macerate everything and then get clogged down in there.
Then you want to look at where those downspouts deposit all of that water that they’re collecting off of the roof line and you want to make sure that they extend, you know, three feet or more away from your home’s foundation; otherwise, that water’s going to get right back into there.
And then also look at the grading all around your property. And you want to make sure that all of that dirt is going to slope away from your house. You want to go down about six inches over four feet and you want to make sure that the grading is done with clean fill dirt and not topsoil; otherwise; it’s just going to hold the water right there against the foundation.
TOM: Now Joe, let’s talk about that gap. How old is your house?
JOE: It’s about 12 years old.
TOM: OK. Well, the way your foundation was constructed – if it’s like most 12-year-old homes – is the footing is poured and the block is built right on top of that. And then there’s probably stone put down. You may or may not have a stone trench under the outside edge with a curtain drain in it. But the cement slab is the last thing that’s put in and they specifically leave a gap between the slab and the wall so if there’s any water that gets onto the walls it will fall down into that crack and then go under the floor as opposed to across the floor. So that’s not necessarily something that we would tell you to seal up. In fact, the only time that sealing that up is a good idea is when you’re dealing with a radon problem and you have to use the floor as sort of the barrier that you’re drawing the gas from under to get outside of your house.
But if you follow the steps of improving the grading; improving the drainage; being really, really careful with your gutter system and then you use the Behr basement and masonry paint, that’s probably going to solve this issue for you once and for all. It’s all about outside maintenance.
JOE: OK. I appreciate your help.
TOM: Thanks so much for calling us at 888-MONEY-PIT.