Crawlspace Drainage

 

ROB: Yes. First, thanks for taking my call.

 

TOM: You’re very welcome.

 

ROB: And the problem I’m having is that I have a sump pump in my crawlspace and whenever it rains quite hard, seems like the water level just comes up and puts water into it and my sump pump just can’t keep up.

 

TOM: OK.

 

ROB: And once it’s on the crawlspace and in the floor, it takes forever to get out.

 

TOM: Too late, yeah.

 

ROB: Yeah, it’s too late then.

 

TOM: Alright, well listen. The first thing is if you’re getting water in the crawlspace consistent with rainfall, then we need to figure out where that water is coming from and it’s usually because there’s a problem with the drainage outside your house, Rob. So I would be looking at the gutters first. You want to make sure they’re clean, they’re free-flowing. Make sure you have enough downspouts. You need one spout for every 400 to 600 square feet of roof surface and you want to take those spouts and extend them four to six feet away from the foundation. Don’t just dump them right at the corner of the foundation.

 

Once you get that working properly, then I want you to look at the grading. This is the angle of the soil around the house. You want it to drop about six inches over the first four feet. So if you need additional soil, add clean fill dirt into that space – clean fill dirt; tamp it down and then you can put a little topsoil or mulch or stone over that. But you want to basically improve that foundation perimeter so it stays as dry as possible.

 

ROB: Yeah, that makes sense and I’ve been looking at those points. The one thing that doesn’t make sense in my crawlspace is one of the wet areas is in the middle of my house.

 

TOM: No, actually that makes perfect sense because what happens is that water collects at the foundation perimeter; it pushes down and under the foundation and then it’s just going to find the point of least resistance. So it’s sort of like a geyser. It meets in the middle and it pushes up. So it’s not always related to the source of the leak. You can have a bad downspout in one corner and have it leak on the other side of the house. I’ve seen it happen many times.