Preventing basement water damage

Risk factors

There are several factors that contribute to basement water infiltration.

• Soil type Foundations backfilled with materials that retain water, such as clay, are more likely to lead to infiltration.
• Slope of the land If water from melting snow or rainwater runs toward the house instead of away from it, the problem isn’t going to go away any time soon.
• Normal wear and tear on materials The lifespan of the waterproofing membrane that protects the foundation, and of the foundation drain (also called a French drain), whether it’s made of clay or plastic, is about 40 years. The foundation drain pipe can also shift, collapse or become blocked. And if your house is more than 50 years old, it may not even have a foundation drain. 
• Rising groundwater The groundwater table may rise as far as your foundation at certain times of year—and potentially cause significant damage to your basement.

Solutions

Your action plan for preventing water damage to the basement must simultaneously ensure that water flows away from the house, and keep it from seeping in. To learn the main options for achieving this, read on.

Adjust the slope of the land

Maintain a positive slope around the house to drain water away from the foundation. Add soil, if need be, to change the slope. Also, correct any problematic sidewalk, patio and driveway inclines. Any sinking could funnel water toward the foundation.

Install or replace gutters and downspouts

Install gutters, or replace the existing ones, with models of sufficient dimensions. Make sure the downspouts and extenders channel runoff water at least two metres away from the foundation. Remember to clean the gutters regularly.

Prevent infiltration through basement windows

Check and repair, if necessary, the caulking around window frames. Make sure there are window wells, with proper drainage, to keep water from getting into the house around windows that are close to or below ground level.

Repair the foundation, membrane or drain

To repair cracks in the foundation, replace the waterproofing membrane, or repair the foundation drain, you will need to excavate. Some cracks, however, can be sealed from indoors.

Install a sump pit and sump pump

A sump pit is a watertight well installed in the basement and connected to the foundation drain. Water flows into the well by gravity. When it fills up to a certain height, this triggers the sump pump, carrying the water either to the city sewer system or far enough away from the foundation for it to be safely absorbed into the ground. Both pit and pump must be inspected and cleaned every year.

To learn more

For more comprehensive coverage of these topics, read our guide Drains and foundations: prevention or repair? If you do experience a basement flood, read our advice to learn how to act quickly.