Moisture in a home is one of the biggest concerns that most buyers have when they are considering the purchase of a home. There is a lot to say about this issue because there are many factors to consider, so this is the first in a series addressing wet basements and this article will start with the big picture.
There are usually two reasons a basement might get water in it or suffer from excessive dampness. First is from water that comes in through the foundation walls when it is raining, and the second is from what might be called underground streams – the natural flow of underground water. Rain water is usually not difficult to eliminate under normal conditions; underground water is almost impossible to eliminate and must be dealt with in the basement.
We’ll start with the easier part: rain water. When it rains it is important to get the water moving away from the house. In our experience, attention to this detail can keep basements dry 99% of the time, and it is usually no more difficult than ensuring that the ground slopes away from the house and that the water from the gutters gets at least 5-6 feet away from the foundation. When a house is built, the ground surrounding the foundation is backfilled after the forms have been stripped away and the water-proofing system is installed. The problem is that the backfill is not normally tamped down and can settle up to 6-8 inches over the course of several years. Additional dirt needs to be added (sometimes several times) to eliminate the sunken areas around the house but this can be a hassle once the landscaping matures. Imagine the situation where someone builds a patio on the back of the house without taking this into account and the patio settles right along with the backfill. A settled patio that drains water toward the foundation usually needs to be replaced. Another problem occurs when homeowners bury the downspouts and they don’t terminate to daylight. Underground drains often fail by separating at joints, collapsing or getting clogged by critters and debris. If underground drains cannot be verified to be working properly they should be considered to be not working at all.
In future articles I will discuss the occasional house that was built in the middle of an underground stream and how that should be handled, water proofing systems, the impact of radon mitigation systems on water proofing systems and backup sump pumps.
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