What Causes Water to Seep From a Foundation Wall?

Soil Types

• The foundation of a home may be sitting on top of mixed soil, and there may be soil that is clay on one side of the house with more sandy soil on the other. This causes shifting in a foundation and can crack the walls, allowing moisture to seep through foundation walls. Soil expands when it is wet and contracts when dry. This constant expansion and contracting is one source of moisture seeping in from the foundation wall through cracks.

  Clay also expands when wet and contracts when dry, making it unstable in shallow foundations, because clay is active close to the surface and puts pressure on foundation walls. Heavy backfill soil coupled with moisture causes hydrostatic pressure to build around the foundation walls, which can causes the walls to bulge inward.

Soil Grading

• Rain, snow and sleet will cause water to collect around your foundation, especially if the house is on a slope or facing uphill. The loose backfill makes the soil around the house more porous, allowing water to collect around the foundation, which eventually can seep into concrete walls or blocks. The best way to prevent this is to grade the soil enough so water flows away from the house. Some homeowners build a trench close to the foundation with the hope of carrying the water away from the house. In many cases, though, this simply traps water against the foundation walls.

Gutters

• Trees close to the house have a habit of dropping leaves, branches and pine needles onto the roof and into gutters. When gutters clog with debris, water collects on the roof and eventually runs off the roof onto the ground near the foundation.

  Downspouts that extend from the gutters to the ground also can cause water to pool around the foundation, which is another way moisture seeps into the walls of the foundation. Gutters should extend away from the house by 10 to 15 feet.

Tree Roots

• Roots from trees may swell and push against the foundation and find their way through cracks in the foundation walls. Roots can cause water to seep through the foundation. When the soil is wet, water follows the path of the roots, directly into your basement. Water also follows the path of holes dug in the soil by burrowing animals.