Basement-Waterproofing101 Waterproofing Information

June 4, 2010

Wall Cracks

Filed under: — admin @ 2:12 pm

Once the wall is poured it is a solid mass and typically a pretty consistent pour. It is not likely that water would pour thru a solid concrete wall, of course, unless there is a crack. Cracks are due to the concrete settling, shrinking, or later movement of the foundation. That concrete cracks is well known and every home with a poured concrete foundation will crack somewhere eventually. The problem is that if a foundation wall is underground and it cracks it will leak.

Below are some photos of foundations cracking. In the first photo notice how serious the leaking is. The second is a typical block wall stair crack coming from a corner. The third is the most common crack, the crack from the bottom corner of a window well. Once this crack allows the water inside the wall you can see the effects upon the wall by looking at the wall/floor seam directly below and toward the corner.

Sealing cracks
Epoxy Injection
Because of the natural movement of a foundation trying to seal a crack with hard resins like epoxy are not going to work long term. Couple this with the fact that epoxy is many times stronger than concrete and that it is placed inside the concrete makes it clear that it will be the concrete that gives over time, forcing the crack to get larger. Not a good solution.

Sealing the Outside
The next most common approach is sealing the outside with either tar, or vapor barrier (see exterior waterproofing for the pros and cons of this approach). Or Drainage is set up outside to simply keep the water away from the crack. Sealing a crack from the outside (if a permanent solution is desired) is really only logical if the wall is under 30 inches underground. The amount of digging and fact that if the wall is low enough and given enough water pressure the water will travel under the wall and still show up on the floor having arisen out of the center of the crack inside the wall where it sits on the footer. This is a problem that no amount of sealing can solve.

What will work
What will work is an interior system that incorporates a vapor barrier that is run under the floor to a sub-floor drainage system and then to a sump well (see photo here). Mil plastic vapor barrier cannot leak and given a place to go water will pour downwards. The problem is if you area is finished or if you do not have a sump pump close by the cost can be considerable. Pair this with the fact that most people prefer a sump pump to be in a closet or utility room. Such convenient placement
only adds to the cost of the drainage. Upside: it works 100%. Downside: its more expensive.

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