Basement waterproofing can seem daunting, but with the right approach, you can tackle it yourself. Whether you’re dealing with water damage or mould or want to prevent future leaks, understanding the common causes and practical solutions is essential. This guide will walk you through waterproofing your basement, ensuring your space remains dry and usable.
Let’s get straight to the point.
Waterproofing your basement involves external and internal measures to prevent leaks and moisture buildup. Start by inspecting the exterior of your home, ensuring gutters and downspouts are clear, grading slopes away from the foundation, and sealing any cracks in walls and floors. Interior waterproofing includes:
- Applying masonry waterproofers.
- Using a dehumidifier for humidity control.
- Potentially installing a sump pump.
Avoiding common mistakes includes relying on temporary fixes or ignoring proper grading. Long-term maintenance is essential, such as regularly cleaning gutters, monitoring the grading, inspecting for new cracks, and maintaining a dry environment with a dehumidifier.
Exterior Basement Waterproofing Steps
Addressing water issues from the outside is the first line of defence, as most basement moisture problems originate there. Here’s how to begin:
1. Walk Around The House
- Inspect the perimeter: Take a thorough walk outside your home, especially after a rainstorm. Look for standing water or spots where water may pool near the foundation.
- Fill low spots: If you notice dips or low spots around the foundation, fill them with additional soil to create a gentle slope away from the house. This prevents water from gathering near the foundation, which can lead to leaks.
- Signs of damage: Also, check for cracks in the exterior walls or any signs of water damage, such as discolouration or erosion.
2. Check Gutters And Downspouts
- Clean gutters regularly: Clogged gutters prevent proper drainage and can cause water to overflow directly near the foundation. Ensure they are free from leaves, twigs, and debris.
- Proper downspout extension: Downspouts should channel water at least 2.4 metres (about 8 feet) away from your home to prevent it from pooling near the foundation. If necessary, use extensions or splash blocks to divert water further away.
3. Inspect Window Wells
- Remove debris: If not properly maintained, window wells around basement windows can trap water. Clear out any leaves, dirt, or debris to keep them functioning correctly.
- Add stone layers: For improved drainage, consider adding a layer of gravel or crushed stone at the bottom of the window well. This helps direct water downward, away from the windows and into the ground.
4. Ensure Proper Grading
- Grade the soil: The ground surrounding your home should slope away from the foundation. A good grading rule is a drop of 1 inch vertically for every 12 inches horizontally. This slope helps redirect rainwater away from the house, preventing it from seeping into the basement.

Interior Basement Waterproofing Steps
If you’ve addressed external issues but still find moisture or leaks inside, interior waterproofing becomes necessary. These steps will help mitigate internal moisture issues:
1. Seal Cracks In The Walls And Floors
- Locate and repair cracks: Check the basement walls and floors for cracks where water might seep through. You can use an epoxy injection kit or hydraulic cement for small cracks, both available at most hardware stores.
- Temporary fix: These solutions can temporarily stop minor leaks, but larger cracks or structural issues may require professional repair.
2. Waterproof The Walls
- Apply masonry waterproofing: Waterproofing paint or masonry sealer should be applied to the interior surfaces of the basement walls. These coatings help block water from penetrating through porous concrete or masonry.
- Preparation: Remove any existing paint or dirt from the walls before applying the waterproofing product to ensure proper adhesion and effectiveness.
3. Install A Dehumidifier
- Manage humidity: If the basement feels damp or you notice condensation on walls and windows, a dehumidifier can help control the moisture levels. This is especially helpful in naturally humid climates or during certain seasons.
- Choose the right size: Ensure the dehumidifier is appropriately sized for the basement space for optimal performance.
Consider Adding A Polyethylene Membrane
- Install a moisture barrier: A polyethylene membrane may be necessary if water continues infiltrating the walls, even after other measures. This plastic sheeting acts as a barrier to water and is installed on the walls behind a drainage system.
- Drainage system and sump pump: In severe cases, the membrane channels water to a drainage system, often connected to a sump pump, which pumps the water away from the basement. This system ensures that water is continuously removed, preventing flooding or significant water accumulation.
Following these steps can significantly reduce or eliminate water problems in your basement. However, if you continue to experience water intrusion despite these measures, consulting a professional waterproofing contractor may be necessary for more extensive solutions.
Avoiding Common DIY Mistakes
When waterproofing your basement, it’s important to avoid common mistakes that many homeowners make:
- Please don’t Rely on Quick Fixes: Products like hydraulic cement or waterproofing paint can offer a temporary solution, but they will only last a while. These products don’t address the root cause of the water problem.
- Refrain from ignoring Grading: Improper grading is one of the most common reasons for basement leaks. Ensure the ground slopes away from the foundation before trying other solutions.
- Be Careful with Temporary Solutions: Avoid plastic vapour barriers or other temporary fixes. Over time, these barriers can disintegrate, allowing water back into the basement.
Products For DIY Basement Waterproofing
When choosing waterproofing products, always invest in high-quality materials. Here are some recommendations:
- Sealants for Cracks: For minor cracks, use epoxy or hydraulic cement. These products are available at most home improvement stores.
- Waterproofing Paint: For larger areas, use masonry waterproofers or waterproofing paint. These coatings are designed to seal the entire surface of the wall.
- Dehumidifiers: A dehumidifier can help control the moisture levels if your basement is prone to condensation.
Why Do Basements Start Leaking?
Basements often leak due to several external factors. Every time it rains, water runs off the roof, around the foundation, and through the soil surrounding your house. A 1,500 sq. ft. roof can shed nearly 1,000 gallons of water for every inch of rain. If your gutters and downspouts aren’t directing water away from the foundation, it can seep into the basement walls, resulting in moisture problems.
Here are the main reasons basements leak:
- Debris-Clogged Gutters and Downspouts: Rainwater must be properly directed away from the house.
- Reverse Grading: Water collects around the basement walls when the ground around the foundation slopes towards the house.
- Footing Drain Failure: Over time, footing drains can clog or break, allowing water to pool around the foundation.
Addressing Hydrostatic Pressure And Rising Groundwater
One of the most common causes of basement leaks is hydrostatic pressure. This pressure builds up when water collects around the foundation and pushes against the walls. If the soil contains clay, the problem can worsen as water gets trapped against the foundation, seeping through cracks and pores in the concrete.
Sometimes, the issue can be traced back to rising groundwater or underground springs. If new construction alters groundwater flow, it may unexpectedly cause your basement to leak.
Settling Cracks And Efflorescence
As houses settle over time, cracks can form in the foundation, which allows water to penetrate the structure. Additionally, efflorescence—the white, powdery residue left behind by water seeping through porous concrete—can be a telltale sign that water is entering your basement. If you spot efflorescence, it’s time to address the moisture problem.
Long-Term Maintenance And Prevention
Even after waterproofing, it’s important to continue maintaining your basement to prevent future issues:
- Regularly Clean Gutters: Keeping gutters and downspouts clear of debris is essential for directing water away from the house.
- Monitor Grading: Check the grading around your house periodically to ensure that water isn’t pooling near the foundation.
- Inspect for Cracks: Look for new cracks in the walls or floor and address them promptly.
- Use a Dehumidifier: Maintain a dry environment in the basement by running a dehumidifier during humid months.
Conclusion
In conclusion, waterproofing your basement is a crucial step in maintaining the structural integrity of your home and preventing costly water damage. By addressing both exterior and interior factors, such as proper grading, sealing cracks, and managing humidity, you can significantly reduce the risk of moisture problems. While DIY methods can be effective for minor issues, always invest in high-quality materials and proactively maintain your waterproofing systems. For more severe or persistent water issues, consulting a professional may be necessary to ensure your basement stays dry and safe for the long term.
FAQs About Waterproofing Basement
How Do They Waterproof A Basement From The Inside?
Apply a masonry waterproofing product to the walls.Seal/coat the interior of the walls with a suitable masonry waterproof product. When the paint dries, the sealant forms a watertight bond to prevent water from seeping. This is how you can waterproof your basement walls from the inside.
Should I Waterproof My Basement?
Ideally, the exterior walls of a basement should be waterproofed during construction. Newer construction mandates this procedure because of many state and local building code requirements, but many older homes may still need exterior waterproofing.
Should I Waterproof My Basement From The Inside Or Outside?
Though labour-intensive and expensive, waterproofing your basement from the outside is the most efficient way of preventing water and moisture build-up around the house’s foundation.
Should You Seal Basement Walls Before Finishing?
Nothing will ruin a beautiful remodelling job like soaked carpets, mouldy drywall and damaged furniture, so a basement must be fully waterproofed before finishing work begins.
What Is The Cheapest Way To Finish A Basement Wall?
If you’re wondering if panelling or drywall is the cheaper finishing option, drywall is generally cheaper than panelling. This is because it requires less attention to detail and finishing work during installation. Drywall also adds better soundproofing than panelling, and it’s easier to repair.