Basements

Published on June 15th, 2014 | by Henri

0

Frost causes cracks in foundation

Q.    I have a room in the basement that was built as an addition afterwards by previous owners. Above it is a cement parking area. The area is damp in the summer so I use a dehumidifier. With this long winter in Canada, with thaw and freeze cycles, I have noted cracks in the foundation bricks. Prior it was treated with Zinsser WaterTite Waterproofing Paint.

The ideal situation is to excavate from the outside but it is not my property and the expense is high for a non-used room.

Questions:

  1. Should I continue to use the Zinsser WaterTite for repair?
  2. Should I look at supporting inside foundation with cement brick foundation on 3 sides?
  3. What do the cracks indicate?

A.    The cracks indicate that frost pressure from outside has pushed the walls in slightly. This may have been caused by extensive water penetration, perhaps from a negative-grade condition outside, which could include the parking area. If the ground and the concrete slope toward the foundation, rain and melting snow in sufficient amounts can saturate the soil, and frost does the rest.

A dehumidifier is fine to use in the summer to lower the relative humidity, which could cause molds to grow.

Painting the inside of hollow block walls with waterproofing coatings is a bad idea. Water can accumulate in the blocks’ cores and cause serious moisture problems in the living areas. I would not recommend using any of these coatings.

The photos you sent do not show that the situation is very serious at this time. But recurring yearly events are likely to aggravate the situation.

The outside grading should be examined carefully, and so should the slope of the parking area. Adding soil to change the slope of the grade is relatively simple, but the concrete area is more involved. Discharge from downspouts should also be checked to make sure that it does not remain close to the foundation.

Since this is not your property, any repairs should be the responsibility of the owners.

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