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Basement Water Infiltration

Causes of Basement Water Infiltration

Improper surface Grading/Drainage is responsible for the most common household maladies: water penetration of the basement or crawl space.

Curing Wet Basement Blues

For some homeowners, a wet, dank basement is as sure a sign of spring as the first tulips blooming in the garden.

Some basements actually flood with water during heavy rains. Other signs of dampness may include excessive condensation on windows resulting in frame rot or simply a musty smell caused by the mould and mildew that thrive in a damp environment. Efflorescence, a whitish powder that appears just above ground level on the outside walls or at the base of the inside basement wall, is a sure sign of dampness.

The first step in curing chronic basement dampness is discovering the source of water leakage. Here are some of the common causes and cures for basement dampness:


Condensation within the basement can come from a number of sources including washing machines, improperly vented dryers, a basement shower, sweating cold water pipes and leaking pipes. Condensation can also form when warm basement air comes in contact with cold outside walls and basement floor.

To counter condensation problems, consider lining the walls with a layer of rigid-foam board insulation. Wrap plumbing pipes with insulation or snap on preformed foam pipe insulators. The use of a dehumidifier is effective in drawing excess moisture from a damp basement. Open the windows occasionally to allow air to circulate. Consider installing a basement vent.


If the soil around the foundation is saturated, the excess water will find its way into the basement through cracks in the walls and floor, or by seeping through untreated walls.

Make sure the soil is graded away from the basement wall at the rate of about a half inch slope per foot. Check that the gutters are clear of debris so that the rainfall is not overflowing and running down the wall of the house. Downspouts should direct the runoff from the roof and discharge it well away from the foundation. If the downspout is not doing its job, water will pool up along the foundation wall and eventually find its way into the basement.

Discourage the growth of clinging vines along foundation walls and locate foundation plantings (shrubs, etc.) well enough away from the walls so air can circulate around the house and through the basement. Keep the bottom gravel surface of window wells clear of debris.

If your basement is damp, it is wise to call in a professional for a site inspection. Leaving the problem untreated can damage the structure and the resale value of your home.

The Year of the Wet Basement

WEDNESDAY, June 22, 1994
Orangeville Banner

(NC)-The arctic temperatures and record precipitation that home owners in Ontario witnessed this winter spawned a common problem this spring- BASEMENT LEAKAGE!

The potential for basement leakage was increased this spring in particular because we experienced rainfall while the ground was still frozen. Frozen ground prevents rain and melting snow water from draining down through the soil. Many home owners that had previously experienced dry basements were faced with leakage and the resultant damage to interior finishes and storage.

Corrective Action

Poor surface drainage of water is one of the main causes of basement leaks. The ground around your home should slope away from the foundation at a rate of one inch per foot, for at least the first six feet. Check the land around your home for proper grading.

It is also important that eaves troughing and downspouts are working effectively. Regular cleaning and repairs are essential. If downspouts are ever suspected of being clogged, disconnected or broken below ground level, they should be redirected to discharge water at least six feet away from the building.

Problem downspouts are usually characterized by basement leakage adjacent to the downspout.

Newer Homes

Even homes built within the past ten years are subject to basement leaks. Leakage commonly occurs from shrinkage or settling cracks in poured concrete foundations. While these cracks do not typically represent a structural problem, repairs are usually desired to prevent further leakage.

As a first step, the surface drainage should be checked. If leakage persists, the cracks can be sealed either by injecting an epoxy resin from the interior, or by excavating the soil beside the crack and patching from the exterior. The exterior repair is more often effective. Crack repair costs vary from $400 to $800, depending on the specific situation. If the home is less than two years old, basement leakage repairs may be covered by the warranty.

More extreme measures

In the vast majority of cases basement leakage is not significant from a structural point of view and can be controlled relatively inexpensively, as discussed above.

However, the presence of damaged perimeter drainage tiles, a high water table or underground streams may call for more extreme corrective measures. These measures should only be used when chronic flooding occurs and surface drainage improvements have been exhausted.

Excavation, damp-proofing and in stalling perimeter foundation drainage tiles (sometimes referred to as weeping tiles) is the typical approach when deemed necessary.