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9 Tips for Waterproofing Your Basement Walls

Published April 4, 2024
Updated: April 4, 2024
Est. Reading: 8 minutes

A dry basement is essential for maintaining the structural integrity of your home, preventing unwanted mold and mildew, and maximizing the usable space in your house. Unfortunately, water intrusion is a common problem for many homeowners, leading to dampness, damage, and unpleasant odors. In such cases, there's one good solution: basement waterproofing. 

This process involves various techniques to prevent water from entering your basement. A combination of interior solutions and exterior fixes work together to keep your basement dry. Here’s how you can go about it:

1) Identify the source of the problem 

Before tackling waterproofing, the most crucial step is pinpointing where the water is coming from. This will guide your repair strategies and ensure you're addressing the root cause of the problem. Look for signs of water intrusion, such as visible cracks in the walls or floor, water stains, or white mineral deposits (efflorescence). These clues can give you information on the entry points of water into your basement. 

Pay close attention to areas like basement windows, the perimeter where the foundation walls meet the floor, and any plumbing penetrations passing through the walls. Other common culprits include faulty window wells, which can collect water and pressure the foundation. You can also check for poor grading around your home, allowing water to pool against the foundation, and clogged gutters that can't effectively divert water away from your house. 

If you struggle to find the source of the leak or suspect a more complex hidden issue, don't hesitate to invest in a professional inspection. A basement waterproofing expert can thoroughly assess using specialized tools and expertise. They might use moisture meters to detect dampness behind walls or employ infrared cameras to identify water flow patterns. Experts say proper diagnosis is key when waterproofing a basement – treating the symptom without addressing the source won't stop the problem for long. 

2) Repair cracks and holes 

Small cracks and holes in your basement walls are a common entry point for water. For hairline cracks and minor holes, you can use hydraulic cement. This material expands as it dries, forming a watertight seal and preventing further water from seeping in.  

However, larger cracks might require polyurethane caulk for its flexibility or epoxy injections for a more robust structural fix. Polyurethane caulk can accommodate some movement in the crack, while epoxy provides a high-strength bond for situations where structural integrity is a concern. 

Don’t attempt DIY repairs if you notice significant structural cracks or suspect serious foundation issues. It's crucial to consult a professional. They may need to implement more substantial repairs using specialized techniques to ensure your home's long-term stability and prevent worsening water intrusion problems. 

3) Fix exterior drainage issues 

Your home's gutters and downspouts protect your basement from water. Neglecting them can be detrimental, as basement water problems can stem from issues with unmaintained gutters and downspouts. As such, ensure gutters are cleaned regularly and free from leaves and debris, which can prevent proper water flow. Install downspout extensions that carry water well away from the perimeter of your house, ensuring water is expelled far enough from the foundation.  

A good rule of thumb is to have extensions directing water at least 5-10 feet out from the base of the house. Moreover, these downspouts should be placed on the gutters every 40 feet to prevent water overflowing. You should also inspect the grading around your home's foundation. The soil should slope away from the house at a minimum of six inches of drop for the first 10 feet. This helps surface water drain away from the foundation instead of pooling against it.  

Add soil to achieve better drainage and prevent water from reaching your basement if necessary. In areas with significant rainfall or high-water tables, a French drain system (also called weeping tile) may be needed to capture and divert large amounts of groundwater away from your foundation. It works as a hidden trench, using perforated piping and gravel to collect subsoil water and safely redirect it away. 

4) Seal windows and window wells 

Even seemingly small gaps around windows and window wells can offer entry points for water. To combat this, use a high-quality exterior caulk designed for masonry to seal gaps between window frames and the foundation. Choose a caulk that provides excellent adhesion, flexibility to accommodate movement, and weather resistance for long-term durability. 

Inspect window wells carefully and ensure they’re functioning correctly. They should be properly installed with adequate drainage, such as gravel or drain pipes in the well. This helps prevent rainwater from collecting and building pressure to force water into your basement. If there's an issue with the windows, such as broken frames, cracked glass or the seals have weakened, it could be the best time to replace them

Consider using window well covers to prevent them filling with debris and leaves, adding an extra layer of protection. They come in various materials like plastic or metal grates. Choose ones strong enough to withstand foot traffic if someone needs to access the window area. Make sure any cover you choose allows airflow to prevent moisture buildup inside the well. 

5) Interior waterproofing coatings 

For persistently damp basement walls, waterproof coatings offer a valuable solution. There are several types of coatings available.

Crystalline coatings penetrate the concrete and react with the moisture to form crystals that block future water penetration. Elastomeric coatings are rubber-like and provide a flexible barrier that can accommodate minor movement in the concrete. For walls without active leaks, a masonry sealant can provide a basic layer of protection against moisture.

Before applying any coating, it's essential to prepare the surface thoroughly. Clean the walls to remove dirt, grime, and efflorescence.  

Make sure you patch any existing cracks or holes to prevent water from seeping through those areas. Most coatings are applied with a roller, brush, or sprayer, and usually require multiple coats for maximum effectiveness. Always follow the manufacturer's instructions for the best results. 

6) Install a sump pump system 

If water frequently pools in your basement, a sump pump is invaluable to your waterproofing setup. This system involves a basin dug into the lowest part of your basement floor. As water collects in the basin, a float switch automatically activates the pump, discharging the water through a pipe that runs outside, well away from your foundation. 

Choosing the right sump pump depends on several factors, including the size of your basement, the typical water volume, and whether you need a backup power source. While some basic sump pump installations can be handled as DIY projects if you have experience, hiring a professional is usually recommended. They can assess your needs, recommend the proper system, and ensure correct installation and wiring. 

7) Consider exterior waterproofing 

For homes with severe or recurring moisture problems where interior solutions aren't sufficient, exterior waterproofing offers a more comprehensive approach. This involves excavating around the foundation, cleaning the surface, and applying a waterproof membrane or coating. It usually also involves installing a new drainage system to divert water more effectively. 

Exterior waterproofing is a more extensive project with a higher cost than interior methods. Usually, exterior waterproofing costs around CAD $11,500, while interior waterproofing costs only around CAD $7,100. However, these costs vary depending on the waterproofing method and the size of the basement.

Due to its complexity and the disruption it can cause to landscaping, it's generally best handled by professional basement waterproofing contractors. Exterior waterproofing is not a DIY project. They have the knowledge, experience, and equipment to execute such a project correctly. 

8) Additional Prevention Measures 

Besides addressing leaks and drainage, consider a few additional measures to help keep your basement dry. A dehumidifier can significantly reduce basement humidity, making the environment less hospitable to mold and mildew growth. Proper insulation on basement walls can help regulate temperature and minimize condensation, another potential source of moisture. 

Modest improvements in ventilation can also aid in moisture control. If your basement has poor air exchange, consider installing vents or periodically opening windows for fresh air circulation. This helps reduce trapped moisture that can contribute to dampness or condensation problems. 

9) Know when to consult a professional 

While many basement waterproofing tasks can fall within the realm of DIY, because the ramifications of water damage to your foundation, or the health impacts mold and mildew can have on your health, we recommend you seek professional help to ensure the job is done right. If you observe significant structural cracks, suspect foundation issues, or if simple fixes don't resolve ongoing water intrusion, consult a basement waterproofing specialist or a structural engineer.

Usually, basement waterproofing solutions can last at least 10 years. Between this period, you may need to do DIY repairs, such as caulking, ensuring clean gutters and downspouts, and potentially upgrading the drainage. However, severe cases such as the foundation degrading and high hydrostatic pressure from groundwater may require you to call a professional. 

For projects like exterior waterproofing or extensive interior renovations, professionals are invaluable. They possess specialized knowledge and equipment to handle these complex jobs effectively and to code. While working with a professional adds cost, it provides peace of mind knowing the job is done right the first time, saving you future headaches and costly repairs. 

Why you need basement waterproofing 

A dry basement isn't just a luxury; it's a cornerstone of a healthy, functional, and valuable home. Waterproofing offers several benefits that make it a worthwhile investment for any homeowner. 

Protects your foundation 

Water is incredibly destructive to building materials, and your foundation is no exception. Concrete is porous, allowing moisture to seep in over time. Constant moisture exposure can cause concrete to deteriorate, leading to cracks, leaks, and overall weakening of the foundation walls. This compromises the structural integrity of your whole house. 

Waterproofing creates a barrier between your foundation and the moist soil, preventing water from reaching the concrete. This protects your house's foundation and maintains its structural integrity. 

Prevents mold and mildew growth 

Basements are naturally prone to higher humidity levels. The excess moisture creates an ideal breeding ground for mold and mildew spores when coupled with a leaky basement. Recent studies show that about 47% of American and 21% of European homes have dampness and indoor mold indicators.  

These harmful organisms cause unpleasant, musty odors and can trigger respiratory problems, allergies, and other health concerns for those sensitive to them. Waterproofing reduces the available moisture in your basement, making it a far less hospitable environment for mold and mildew to thrive, improving indoor air quality and protecting your family's health. 

Increases usable living space 

A damp, leaky basement is far from inviting and is often relegated to basic storage. You can transform a previously unusable basement into a dry and welcoming environment through effective waterproofing. This opens up numerous possibilities! Utilize the additional space as a cozy family room, a home office, a dedicated gym area, a playroom for children, or simply for extra storage that's safe from water damage. 

Improves home value 

A dry and functional basement is a major selling point for real estate. Potential buyers know the problems of leaky basements, and a dry basement adds significant value to your home. Waterproofing can attract more buyers and often leads to a higher selling price as buyers know the basement is in good condition. 

Reduces maintenance costs 

Water problems in basements have a way of escalating. A small crack can worsen over time, and dampness often leads to more extensive damage. Ignoring these issues almost guarantees the need for costly repairs down the road.  

Waterproofing your basement is a proactive investment. It prevents water damage that can affect your foundation and the structure of your basement walls, flooring, and any belongings stored in the space. 

Addressing water intrusion early prevents small issues from becoming major problems, saving you significant money on repairs and replacements. On average, foundation repairs can cost CAD $7,400. This can be high as it will also be followed by subsequent waterproofing compared to just waterproofing your basement and protecting your foundation from the initial start. 


A dry basement significantly contributes to a healthier and more valuable home. By addressing water problems promptly and employing the right waterproofing techniques, you can prevent costly damage and enjoy a functional and comfortable basement space. Remember, some situations require professional assistance to ensure the best long-term results.

Investing in a dry basement is, indeed, an investment in the overall well-being of your home.

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