What causes basement leakage? “Water in the wrong place” is the most obvious answer to that question, but there are a number of other issues that are not quite as obvious, but are just as important. Since 85% of all basements built leak at some point in their life cycle, they all must have some common problems.
Hydrostatic Pressure: Hydrostatic pressure is a result of water at the surface being pulled downward by gravity. The pressure increases as you go deeper into the soil next to your foundation wall, because of the weight of the water above.
Here are five common ways water can enter your basement or crawl space:
- Through floor cracks
- Through wall cracks & mortar joints
- From bleeding and sweating of walls
- Over the footer
- Under the footer
Basements are built to leak. That’s a shocking statement, we realize, but it’s a true statement. Common, approved construction methods build in potential basement leakage problems at almost every step of the process. Think about it—a basement is nothing more than a large hole in the ground, surrounded by soil that can be saturated with water, over and over again. As the house ages, it becomes more susceptible to leakage, as new pathways are created for groundwater to follow, directly into the basement.
Basement construction begins with site preparation. Excavation creates a large hole, slightly larger than the foundation “footprint”. The more compacted undisturbed terrain that can be left in place, the better, since this virgin soil typically sheds water naturally. After the hole is dug, the next step is to create the footing. The footing is the base of the foundation and consists of poured concrete, sometimes reinforced by steel rebar. The construction of the footing is very important, since it is designed to permanently support the house and distributes the weight of the structure into the ground.
The principle of the French drain is a sound one—devise a way to position a drainage pipe in the correct place so that it quickly eliminates water that could otherwise enter your lower level. Historically, the French drain is a concept from the 1800’s. Henry F. French introduced the concept in 1859 and surprisingly, for the last 150+ years there have been only a few changes. The result remains the same—the French drain continues to be a limited and temporary method in many situations.
Hydrostatic Pressure is an important concept to understand, when faced with basement leakage. Hydrostatic pressure is a measurement of the amount of force that is being exerted against your foundation walls, the footing and the floor slab, by any water in the soil. This pressure is a result of water at the surface being pulled downward by gravity. The hydrostatic pressure increases as you go deeper into the soil next to your foundation wall, because of the weight of the water above.
If you look at the walls in your basement and notice wet areas, darker areas that appear to feel cooler or even damp to the touch, or a fuzzy white deposit, or even water trickling down your walls, then you have seepage. This is not an ideal situation, and it can be unhealthy for both people and pets because it can provide ideal conditions for mold, mildew and odors to develop. If you are experiencing this type of water entry into your lower level, you should seek the help of a professional, because these problems don't go away unless something is done to change the situation.