Friday, November 16, 2007

Waterproofing The Foundation

Before I can backfill the basement, the outside of the basement walls have to be waterproofed. The traditional way of doing this was to spread (or spray) a thick, black, tar-like coating on the foundation walls and footings... a very messy job. With an ICF foundation, that process can be greatly simplified by using a peel-and-stick waterproofing membrane. It's basically tar-on-a-roll, with a layer of tar sandwiched between a plastic facing on one side and a peelable backing on the other side. In very simple terms, you cut a piece off the roll, peel the backing off, and press it into place. The tar-like substance sticks to the ICF block very well and it's relatively clean to work with.

You start by putting a short piece at the bottom of the wall and down overtop the footing and the plastic footing bag. Here's where the plastic footing bags that I used for the footing forms tie in nicely with the waterproofing membrane; any water that comes from the soil or comes down the side of the house in a heavy rain can't make it's way into the house because now the entire basement is encased in plastic. At least that's the theory.

After the footing piece is done, the walls can be done. You simply cut a piece about six feet long, hold it up against the wall, start peeling the backing off, and press it to the wall as you go. There are lines scribed into the ICF blocks that you can use as a reference to get everything straight. When you get down to the bottom, you overlap it right on top of the footing piece applied previously. Once it's all attached to the wall, you go over it with a rubber roller to make sure that it's really stuck well. Each subsequent piece overlaps its neighbour by about three inches and the corners will get a double layer.

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