Adding Drain System to a Concrete Foundation

by | Sep 6, 2021

Today we’re looking at a drain tile system in a cast-in-place foundation, or poured concrete basement. “Cast in place” means the concrete is poured between forms. Usually, the finished walls and concrete floor all sit on a footing. But…

The Problem

The drainage system was installed with a finished basement already in place and the floors were poured afterward. This is a bad idea because it leaves the bottom sill board with no concrete under it. That means the wood is vulnerable to water, bugs and other damage. In this case, after the drainage system was put in, the concrete was actually poured up and onto the wood. All of this was an extreme no-no. 

The Solution

The good news is, it’s an easy fix. So, how do we handle these kinds of situations? There are no police for us. So we handle it the same way any major engineering group would.

First, we remove the old drainage system. We put geotech in the trench. Geotech is a fabric that allows water through, cleaning it as it moves.

Then, instead of using a crushed rock with a minus (minus gravel compacts and can cause binding and clogging) or even clean gravel, we use river rock. So it goes in this order- fabric, river rock, drain tile pipe, another layer of river rock, then plastic over the top of that. And we’ll bring the drain tile system across the front of the house.

After that, the place will be in good shape. If the poured concrete walls were in rough shape, we’d put a cove plate in. But there’s no need for a cove plate for this house. And we’re talking about 45′ of drain tile. That’s not a giant situation, just  20 x 25 feet.  

After we replace the drain tile, we’ll put in a closed basin for the sump pump in the back corner. There’s an outlet above it already. And the panel is grandfathered. Then we’ll fix the discharge pipe that’s already  in place too.

The concrete walls are in good shape,  but we do have to pull up the rest of the drywall. And since we’re going to do this job right and pour new concrete, the bottom sill board will be pulled out too.

It’s really important that the new sill board be made of treated lumber. It’s also important that it be glued down rather than nail it to the new concrete. Then the homeowner can scab into their two by fours and put the drywall back up.  This place will be in good shape at that point in time.

Other Notes

 We’ve discussed the basement floor with the homeowner who wants to do something with it. An epoxy resin is really easy to apply and it’s attractive. But the concrete has to be clean and dry when it’s applied, and if it’s not dry, it could start to fog and will turn white. Staining the concrete is usually a better idea in the long run. 

 The homeowner is also planning to add a porch. They will need to show our information to the gentleman that’s going to be doing that work. The real issue is the big void that’s in the front corner of the house by the foundation. We want to make sure that it’s filled with a cementitious material and it is mechanically tamped, so that there are no voids. And we want to stay away from loose rock because we don’t want to entomb a bunch of water there.

The reason? We know that 36 gallons of water is 300 pounds. The strength is 3,000-pound force, (300 pounds, 10 percent). So we have to be very careful not to put hydrostatic pressure on the foundation. If we keep up with this, it will be fine. If not, there will be cracks in the front walls and foundations.

This is Steve with Waterproof Solutions! Thanks for joining me!

 

 

 

The Drain System

First, we would remove what’s there. We would put a geotech style on the trench, which is fabric that allows water through, cleaning it as it moves.

Then, instead of using a crushed rock that has minus on it and (minus is what’s left on your hands from a crushed rock), and it can cause binding and clogging. Instead we use River Rock. So the fabric, river rock drain tile pipe, river rock, then plastic over the top of that.

So now you’re in good shape. If the walls were in rough shape, we’d put a cove plate in. But there’s no need for a cove plate for this house. We’re talking about 45′ of drain tile. That’s not a giant situation, 20 feet and 25 feet over here, pump in the back corner. There’s an outlet above it already. The panel is above it, so it’s grandfathered. We’re going to put a close base in and fix that discharge is already in place.

The walls are in good shape, we’re going to have to have the rest of the drywall taken up, though, because we’re going to do this right in this bottom sill board will get taken out. What’s really important about this now is that the sill board is treated lumber. It’s also important that it be glued down rather than nail it to the new concrete. Then you can scab into your two by fours and put the wall back up.  You’ll be in good shape at that point in time.

What About the Floor?

We talked about the floor. You know, trying to do an epoxy floor is real easy to apply and it’s attractive. But if it isn’t clean and dry enough before installation, it could start to fog. Staining the concrete is usually a better idea in the long run. We could talk about that another time.

So we are going to bring the drain tile system from this area. We’re going to bring across the front of the house.

Adding a Patio

We talked about, a patio outside. Show this to the gentleman that’s going to be doing the front porch. The real issue is the big void that’s in the corner over here. We want to make sure that’s filled with a cementitious material and it is mechanically tamped, so that there are no voids. We want to stay away from rock because we don’t want to tomb a lot of water there. We know that 36 gallons of water is 300 pounds.

The strength is 3,000 pound force, (300 pounds, 10 percent). So we have to be very careful. So that’s the whole issue with the front porch. By keeping up with this, we’re going to be fine in the sense that we’re going to get rid of our hydrostatic pressure. But it’s just the idea of having cracks on the front wall.

We’ll put it in a folder and we’ll send it to you with the bill. We appreciate the opportunity.

Thanks.