How to prevent basement water infiltration

How to tell if your basement has water infiltration issues

Watch for these common signs of basement water infiltration inside your home: 

• Excessive basement humidity, visible through damp spots on walls or floors (wet walls after heavy rain) 

• Musty or mouldy odours 

• Peeling paint or blistering on walls 

• Visible mould or mildew 

• Warped or uneven floors 

• Presence of puddles (standing water) after heavy rainfall 

Is your basement at risk of water infiltration?

Your basement may be at risk of water infiltration if certain warning signs or conditions are present. A sloped yard that directs water toward your home, a property near a groundwater table, clay soil, foundation cracks, missing or clogged French drains and drainage pipes, or poorly directed gutters can all increase the risk of infiltration. 

Proper yard maintenance, foundation waterproofing, and drainage system upkeep can significantly reduce the likelihood of water entering your basement. 

How to prevent basement water infiltration

To prevent infiltration, divert water away from your home. Make sure it cannot enter through walls, windows, or the foundation. Here are several actions that can make a difference: 

Adjust the slope around your home

Maintain proper grading around your house to direct rainwater away from the foundation. Add soil where needed to correct the grading. Also, ensure sidewalks, patios, and driveways are properly sloped. Any uneven surfaces could channel water toward your foundation. 

A well-designed slope improves water drainage and helps prevent infiltration around the house. 

Install or replace gutters

Install new gutter and downspout systems or replace existing ones with properly sized models. Ensure downspouts discharge water at least two metres (six feet) away from the foundation. Don’t forget to clean your gutters regularly to prevent clogs. 

Check the condition of your drain

Your foundation drain plays a key role in directing water away from the base of your home. If it’s missing, damaged, or blocked, water may pool against the foundation and cause leaks or infiltration. 

Fixing the problem often involves excavating around the foundation walls to repair or replace the drain. Take the opportunity to add a waterproof membrane and improve drainage around your home to prevent future issues. 

For more details, read our guide Drains and Foundations: Prevention or Repair? 

A well-designed drainage system minimizes water accumulation near your foundation and lowers the risk of basement flooding. 

Seal basement windows and install window wells

Check and improve the caulking around your basement windows. Install properly drained window wells—also known as dry wells—to prevent water from seeping in through windows located close to the ground. 

Seal foundation cracks to block water entry

Inspect your home’s foundation for cracks. Clean them thoroughly to remove dust and debris. Then apply a suitable crack sealant using a trowel or caulking gun. 

Ensure the sealant penetrates deep into the crack and smooth the surface for an even finish. Unsealed cracks are an easy entry point for water infiltration. 

Waterproof basement walls

To protect your basement walls from excessive moisture levels, apply a basement waterproofing product. These coatings create a watertight barrier that prevents water from seeping through. Clean the walls first to remove dirt or mould, apply one coat of waterproofing paint, let it dry, and then apply a second coat for optimal protection. 

Install a sump pit and sump pump

A sump pit is a sealed basin installed in the basement and connected to the foundation drain. Water flows into the pit by gravity and is collected there before being pumped out by a sump pump. The water is discharged into the sewer or away from the house, where the ground can absorb it. Inspect and clean both the sump pit and pump annually to keep them working efficiently. 

How much do basement water infiltration repairs cost?

The cost of repairing basement water infiltration can vary depending on the scope of the work required. 

Simple interior crack repairs may cost a few hundred to a few thousand dollars. More extensive work, such as foundation excavation, membrane installation, or drain replacement, can quickly become expensive. In some cases, the total can reach several thousand—or even tens of thousands—of dollars. 

Act quickly if you notice water infiltration

Even a small water leak can cause major structural damage to your home. If you suspect a problem: 

• Contact your home insurance provider as soon as possible. Some types of water damage are covered, while others are not. Take photos to support your home insurance claim. 

• Dry affected areas and belongings quickly to prevent mould growth. For thorough cleaning and water damage restoration, hire a professional service. 

In summary, a dry, waterproof basement depends on a combination of prevention, regular maintenance, and targeted repairs. By acting before water infiltration occurs—or at the first signs of trouble—you protect not only your home’s structure but also your comfort and peace of mind.