Concrete Block Foundation Internal De-Watering

A relatively inexpensive and highly effective waterproofing technique, compared to external excavation and waterproofing, is internal de-watering. This technique, used for getting rid of the water that pools withing concrete or cinder block foundation walls, effectively replicates the weeping tile system around the footing on the exterior of the foundation, by creating a perimeter drainage system on the inside of the basement, so that no outside digging is required. Concrete block/cinder block foundation de-watering allows a block foundation, into which water has pooled, to drain; thus preventing the wall from leaking into the basement and preventing the concrete blocks from deteriorating further. Properly installed, an internal de-watering system will keep your basement dry for many years.

Internal de-watering requires exposure of the bare walls inside the home. Once the walls are exposed, de-watering is accomplished via a series of simple steps as follows:

1. A trench is cut into the basement floor slab;

2. The fully exposed bottom blocks have weeping holes drilled into them;

3. A 3" perforated PVC pipe is installed next to the footing;

4. An air gap membrane is installed along the wall to grade, or slightly below grade;

5. If not already installed, a sump liner and submersible pump are installed beneath the floor, with the top flush with the floor;

6. The PVC pipe is connected to the sump liner, beneath the floor, so that the water draining out of the blocks will be mechanically evacuated to the exterior; and

7. The PVC pipe and lower portion of the membrane is then covered with a gravel layer and concrete is poured over top and levelled. On completion, all you will see is a scar in the floor along the wall, a membrane fastened to the wall, and a sump pump discharge pipe to the exterior.

The following illustration depicts how water enters and pools within a concrete block foundation:

The following illustrations depict the steps involved in performing internal de-watering:

Here is what a finished job looks like:

Below is a typical sump pump installation that is part of the internal de-watering system. Note: It is possible to conceal the discharge pipe within the framed basement walls by modifying the configuration of the discharge so that it is "discrete" (beneath the concrete floor and travelling up the wall behind the drywall).

For a dry and healthy basement call AquaGuard Injection and Waterproofing™ today at 1.888.284.2384.