How To Waterproof Basement Windows?

How To Waterproof Basement Windows

Waterproofing basement windows is a critical task for any homeowner looking to protect their property from water damage. Basements are particularly susceptible to water infiltration due to their location below ground level, making them vulnerable to leaks through windows. Water leaks through basement windows can lead to a myriad of problems, including mold growth, structural damage, and ruined personal belongings. 

This guide “How To Waterproof Basement Windows” aims to provide a comprehensive, step-by-step approach to effectively waterproofing your basement windows, ensuring a dry and safe basement environment. Readers can expect to learn about the necessary tools and materials, detailed waterproofing steps, and additional tips to prevent water from entering their basements.

Tools and Materials Needed to Waterproof Basement Windows

Before starting the waterproofing process, it’s essential to gather all the necessary tools and materials. Having everything ready will make the process smoother and more efficient.

Essential Tools for Waterproofing

Caulking gunUsed to apply waterproof sealants and caulks
Putty knifeHelps to smooth and finish caulk and sealant applications
Utility knifeUseful for cutting and trimming materials
Screwdriver setNeeded for installing window well covers and other hardware
Tape measureCrucial for accurately measuring and planning waterproofing projects
LevelEnsures proper installation of waterproofing components
Safety glovesProtects hands during the waterproofing process
Safety gogglesPrevents eye injuries from debris or chemicals
Cleaning brushHelps to prepare surfaces for waterproofing applications

Waterproofing Materials

Waterproof sealant (silicone-based or polyurethane)Seals cracks, gaps, and joints to prevent water intrusion
Exterior-grade caulkProvides a flexible, waterproof seal around windows, doors, and other openings
Window well coversHelps to direct water away from the foundation
Gravel and landscape fabricImproves drainage around the foundation
PVC pipesUsed in drainage systems to channel water away from the home
French drain componentsHelps to intercept and divert groundwater away from the foundation
Waterproofing coatings (liquid or membrane)Provides a continuous, waterproof barrier on walls and floors
Cleaning solution (mild detergent or vinegar solution)Prepares surfaces for waterproofing applications
Waterproofing paintAdds an extra layer of protection to walls and floors

Step-by-Step Guide For How To Waterproof Basement Windows

Waterproofing basement windows is crucial to prevent water damage, mold growth, and structural issues. Here’s a comprehensive guide to help you ensure your basement windows stay dry and secure.

Step 1: Inspect and Clean the Area

Start by thoroughly inspecting the window area for any signs of damage or leaks. Look for cracks, gaps, and any deterioration in the window frame or surrounding walls. Pay close attention to the caulking and seals around the window, as these are common areas where water can seep through. Use a flashlight to check for hidden issues and ensure that no small cracks are missed.

Once the inspection is complete, clean the window frame and the surrounding area thoroughly. Remove any dirt, debris, and old caulk or sealant. Use a wire brush to scrub away any loose material, and clean the surface with a mild detergent and water solution. Rinse well and let it dry completely. A clean surface ensures better adhesion of the waterproofing materials.

Step 2: Seal Cracks and Gaps

After cleaning, carefully examine the window frame for any cracks and gaps that could allow water to enter. Use a magnifying glass if necessary to spot smaller cracks. Mark these areas so you can address them systematically.

Choose a high-quality waterproof sealant or caulk suitable for exterior use. Silicone-based sealants are often recommended due to their flexibility and durability. Apply the sealant to the identified cracks and gaps, ensuring it penetrates deeply to provide a solid seal. Smooth the sealant with a caulking tool or your finger to ensure an even application and to avoid air bubbles. Let it dry according to the manufacturer’s instructions.

Step 3: Install Window Well Covers

Window well covers are essential for preventing water, debris, and pests from entering your basement through the window wells. They also help in reducing energy loss by providing an extra layer of insulation.

Choose window well covers made from durable materials like polycarbonate or reinforced plastic, which are resistant to cracking and can withstand harsh weather conditions. Measure your window wells accurately to ensure a proper fit.

To install the covers, place them over the window wells and secure them with the provided hardware. Make sure they fit snugly against the well walls and that there are no gaps where water can seep through. Some covers come with adjustable clips or brackets to ensure a tight fit.

Step 4: Improve Drainage Around the Window

Good drainage around basement windows is vital to prevent water accumulation and seepage. Start by checking the slope of the ground around your home. The ground should slope away from the foundation to direct water away from the windows.

Consider installing or improving drainage systems around your basement windows. French drains or gravel trenches are effective options. These systems help to collect and redirect water away from the windows. Install a perforated pipe at the bottom of the trench, covered with gravel and landscape fabric to filter out debris. Connect the drain to a suitable outlet away from the house to ensure proper water diversion.

Step 5: Regular Maintenance and Inspection

Regular inspections are essential to maintain the effectiveness of your waterproofing efforts. Schedule periodic checks, especially after heavy rains or during seasonal changes, to identify any new issues early.

Maintain the area around your basement windows by keeping it clear of debris and vegetation. Clean the window wells regularly to prevent the buildup of leaves and dirt. Reapply sealant as needed if you notice any cracks or gaps reappearing. Ensure that the window well covers remain securely in place and replace them if they show signs of damage.

By following this step-by-step guide, you can effectively waterproof your basement windows, ensuring a dry and safe basement environment. Regular maintenance and timely repairs will help prolong the life of your waterproofing efforts and protect your home from potential water damage.

Additional Methods to Prevent Water from Entering Your Basement

Keeping your basement dry is essential for preserving your home’s structural integrity and preventing water damage. Besides waterproofing basement windows, there are several additional methods to prevent water from entering your basement. These methods focus on proper drainage, foundation maintenance, and effective water diversion techniques.

Proper Grading Around Your Home

Ensuring proper grading around your home is a fundamental step in preventing water from entering your basement. The ground around your house should slope away from the foundation to direct rainwater away. Regularly check the grading to ensure it remains effective and make adjustments as necessary. This helps to prevent water from pooling near your foundation, which can lead to leaks and basement flooding.

Install Gutters and Downspouts

Gutters and downspouts are essential for effectively managing rainwater. Install gutters along the edge of your roof to collect rainwater and direct it into downspouts. Ensure these downspouts extend at least six feet away from your home to prevent water from pooling near the foundation. Regularly clean the gutters to avoid clogs, which can cause water to overflow and seep into the basement.

Use a Sump Pump

A sump pump is a vital device for any basement prone to water accumulation. Install a sump pump in a sump pit at the lowest point of your basement to collect and pump out any water that gathers. Regularly test the sump pump to ensure it functions properly, especially before periods of heavy rainfall. Maintaining the sump pump can prevent significant water damage during floods.

Apply Waterproof Coating to Basement Walls

Applying a waterproof coating to your basement walls can create a barrier against moisture. Use a high-quality waterproof sealant on both the interior and exterior surfaces of the walls. This extra layer of protection helps to keep water from seeping through cracks and porous areas, maintaining a dry basement environment.

Install a French Drain System

A French drain system is an effective way to manage water around your home. This system consists of a trench filled with gravel or rock containing a perforated pipe that redirects surface and groundwater away from the foundation. Installing a French drain can significantly reduce water accumulation around your home, thereby preventing basement flooding.

Maintain Your Landscaping

Proper landscaping maintenance is essential to prevent water from entering your basement. Ensure that plants and landscaping elements are not planted too close to the foundation, as roots can cause cracks and allow water to seep in. Opt for native plants that require less water, reducing the risk of water buildup near your home.

Seal Cracks in Foundation Walls and Floors

Regularly inspect your foundation walls and floors for any cracks or gaps. Seal these cracks with appropriate materials, such as hydraulic cement or epoxy, to prevent water from infiltrating your basement. Consistent maintenance and timely repair of any new cracks will help preserve the integrity of your foundation and keep your basement dry.

Install Window Well Drains

If your home has below-ground-level windows, consider installing window well drains. These drains prevent water from accumulating in the window wells and seeping into the basement. Properly installed window well drains can protect your basement from water intrusion through the windows, particularly during heavy rains.

Common Mistakes to Avoid When Waterproofing Your Basement Windows

When waterproofing basement windows, avoiding common mistakes is crucial for a successful project:

  1. Ignoring Small Cracks: Small cracks can quickly become larger problems if left unaddressed. Always seal even the smallest cracks and gaps.
  2. Using the Wrong Sealant: Use a high-quality waterproof sealant suitable for exterior use. Not all sealants are created equal, and the wrong type can fail under pressure.
  3. Poor Drainage Solutions: Improperly installed drainage systems can cause more harm than good. Ensure that drainage systems are correctly installed and maintained.
  4. Neglecting Regular Maintenance: Waterproofing isn’t a one-time task. Regular maintenance and inspections are necessary to ensure continued protection.
  5. Incorrect Installation of Window Well Covers: Ensure window well covers fit properly and are securely fastened to prevent water from getting in.


Waterproofing basement windows is an essential step in protecting your home from water damage. By following the steps outlined in this guide—inspecting and cleaning the area, sealing cracks and gaps, installing window well covers, improving drainage, ensuring proper grading, installing French drains, applying waterproofing coatings, and performing regular maintenance—you can effectively keep your basement dry and safe. 

Avoid common mistakes and consider additional preventive measures to enhance your waterproofing efforts. With diligence and the right approach, you can safeguard your basement and enjoy a dry, comfortable living space.

Boston Foundation Repair is your trusted concrete contractor in Boston, MA, specializing in foundation repair services. We ensure your home’s stability and safety with expert solutions. Our team also provides top-notch waterproofing for basement windows, protecting your property from water damage. Choose us for reliable, high-quality repairs that last. Contact us today to secure your home’s foundation and prevent future issues. 

Frequently Asked Questions

Q.1 How to protect a basement window from rain?

Ans To protect a basement window from rain, install window well covers to prevent water accumulation. Ensure proper drainage around the window well, and seal any gaps or cracks with waterproof caulk. Adding exterior drainage systems and maintaining gutters can also help divert rainwater away from the basement window.

Q.2 How do you divert water from a basement window?

Ans Divert water from a basement window by installing a window well with a cover to block rain. Ensure proper drainage by adding gravel at the bottom of the window well. Use downspout extensions and grading around your home to direct water away from the foundation. Seal any gaps with waterproof caulk.

Q.3 How do I stop my basement window from leaking?

Ans Stop a basement window from leaking by sealing cracks and gaps with waterproof caulk. Install window well covers to keep out rain and debris. Ensure proper drainage around the window well with gravel and a drainage pipe. Regularly check and maintain gutters and downspouts to direct water away from the foundation.

Q.4 Is it OK to seal basement windows?

Ans Yes, it is OK to seal basement windows. Sealing prevents water leaks and drafts, enhancing your basement’s insulation and protection. Use waterproof caulk to seal gaps and cracks. Ensure proper ventilation to avoid moisture buildup. Combining sealing with window well covers can further protect against water intrusion.

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