LESLIE: Paul in New York is on the line with some basement water leakage. What can we do for you at your money pit?
PAUL: I’d like to finish my basement, make it a more usable area. But I have a problem with some water leakage at times. I believe the construction is called a “floating slab” where there’s a weep channel around the edge of the basement that goes into a sump pit.
TOM: Tell me, when do you seem to have the biggest problem with basement water leakage?
PAUL: Heavy rains.
TOM: Alright. So I’ve got great news for you. You don’t need anything more than some minor adjustment in the grading and drainage outside to solve basement water leakage.
Whenever you have water that leaks and after a heavy rain, that’s always caused by exterior drainage conditions that are just not right. And usually, it’s as simple as not having the right gutter set up around the house. You need to have gutters. They need to be clean and free-flowing and the downspouts – now, this is where most people get it wrong – have to be extended a minimum of 4 to 6 feet away from the house. Because those first few feet at the foundation perimeter are where water collects and saturates and then goes down into those basement walls and shows up as a leak inside. So I want you to look at that very, very carefully.
The second thing is the angle of the soil at the foundation perimeter has to pitch away from the house. And it has to do so with soil that can drain. Sometimes we see people that pile up a lot of mulch around the house or they have a lot of topsoil around the house or they have sort of like a brick edging around some landscaping that kind of acts as a retention pond and it holds the water against the house. You basically want to move that water. That first few feet around the house, move it away. Get it going so that it drains away. It can drop about 6 inches over the first 4 feet. But after that, it can move slower with a gentler slope away from the rest of the house.
Those two things will solve the vast majority of flooded crawlspaces and flooded basements in this country. The only time you need to install a very expensive, sub-slab drainage system is when you have a high water table. And that behaves differently. When you have a high water table, water comes up very slowly. Generally, in the winter it’s typically higher and then goes down very slowly. And you can actually physically see that water sometimes ponding in the sump pit or something like that. But when you have rain or snow melt and you get water in your basement, that’s because of drainage and that’s really easy to fix.
Good luck with that project.