Is Sealing Concrete Basement Floors a Good Idea? What’s the Best Waterproof Sealer to Use?

When it comes to maintaining a healthy and comfortable living space, one crucial area homeowners often overlook is their basement. A basement with a concrete floor is prone to moisture issues, leading to mold growth, dampness, and even structural damage. To prevent these problems, sealing it with a waterproof concrete sealer is an excellent solution.

This comprehensive blog post will discuss the benefits of sealing basement flooring, the best waterproof sealers available, and how to apply them properly.

Why Do Basements Leak?

Basements can leak for various reasons, often stemming from issues with the foundation, concrete construction, or surrounding environment.

Here are the most common ones:

1. Hydrostatic Pressure

Hydrostatic pressure is the force water exerts in the soil surrounding your basement walls and floor. When it rains or snow melts, the water table around your home rises, increasing the hydrostatic pressure against your basement walls and floor. This pressure can cause water to seep through cracks, joints, and porous concrete, resulting in leaks.

2. Poor Drainage and Grading

Improper drainage and grading around your home can cause water to pool near your foundation, increasing hydrostatic pressure and potential basement leaks. Ideally, the ground around your home should slope from the foundation to direct water away from the structure. Additionally, gutters and downspouts should be clear and functioning correctly to prevent water from overflowing near the foundation.

3. Cracks and Holes in Foundation Walls and Floor

Over time, basement floor cracks and foundation walls can develop holes due to natural settling, shrinkage, or external pressure. These openings allow water to seep into your basement, causing leaks. Hairline cracks may only result in minor leaks, while larger cracks and holes can lead to significant water intrusion and damage.

4. Cove Joint Seepage

The cove joint is the area where the basement walls meet the floor. This joint is a common source of basement leaks because it’s a natural weak point in the structure. As hydrostatic pressure increases, water can seep through the cove joint, damping or flooding your basement.

5. Window Well Leaks

Basement windows installed below ground level typically have window wells to prevent soil and water from entering the window. However, if the window well is not correctly installed or maintained, it can collect water, leaking through the window and into your basement.

6. Penetrations in Walls and Floor

Penetrations in basement walls and floors, such as pipes, conduits, or ductwork, can create openings for water to enter your basement. If these penetrations are not adequately sealed, they can be a source of basement leaks.

7. Sump Pump Failure

A sump pump is installed in a basement to remove excess water accumulating in a sump basin. If your sump pump fails due to a power outage, mechanical failure, or poor maintenance, it can’t effectively remove water from your basement, leading to leaks and potential flooding.

8. Construction Issues

Poor construction practices or materials can contribute to basement leaks. For example, if the concrete used for your basement walls and floor is not adequately mixed or cured, it can be more porous and prone to cracking, allowing water to seep.

9. Condensation

While not technically a leak, condensation can cause moisture issues in your basement. When warm, humid air comes into contact with cold basement surfaces, it can condense, creating moisture on walls, floors, and other surfaces. This moisture can mimic the appearance of a leak and contribute to dampness, mold, and mildew growth.

Why Seal Your Concrete Basement Floor?

Moisture Protection

Concrete is naturally porous that can absorb moisture from the ground and surrounding air. Over time, this moisture can lead to damp basements, water seepage, and even structural damage. Sealing your concrete basement floor with a waterproof sealer creates a barrier that prevents water and moisture from penetrating the surface, keeping your basement dry and protected.

Mold and Mildew Prevention

A damp basement creates the perfect environment for mold and mildew growth. These fungi thrive in moist conditions and can cause health problems, especially for those with allergies or respiratory issues. By sealing your concrete basement floor, you reduce the risk of mold and mildew growth by preventing moisture from entering the space.

Enhanced Durability

Sealing your concrete basement floor not only protects against moisture but also improves the durability of the surface. A high-quality sealer can help prevent hairline cracks, abrasions, and wear and tear caused by foot traffic, furniture, and other daily activities. This added protection ensures your basement floor remains in good condition for years.

Improved Aesthetics

Aside from its practical benefits, sealing your concrete basement floor can enhance its appearance. Sealers are available in various finishes, from matte to glossy, and can even be tinted to match your preferred color scheme. A well-sealed floor looks clean, polished, and inviting, making your basement a more attractive and usable space.

Choosing the Best Basement Floor Sealer

Several types of waterproof sealers are available for concrete basement floors, each with advantages and disadvantages.

Here, we will discuss four popular options:

1. Penetrating Concrete Sealers

A Penetrating concrete sealer is an excellent choice for those seeking long-lasting protection without altering the appearance of their concrete basement floor. These sealers penetrate deep into the concrete, filling tiny pores and capillaries to create a water-resistant barrier. Some popular types of penetrating concrete sealers include silicates, siliconates, and silane/siloxane blends.


  • Long-lasting protection
  • It does not alter the appearance of the concrete
  • Allows the concrete to breathe, preventing moisture buildup
  • Resistant to both water and water vapor


  • It may not provide as much surface protection as other sealers
  • It can be more expensive than other options

2. Acrylic Sealers

Acrylic sealers are a cost-effective option that provides a thin protective layer on the surface of your concrete basement floor. These sealers are easy to apply and dry quickly, making them popular for DIY projects.


  • Affordable and easy to apply
  • Enhances the appearance of the concrete
  • It offers UV resistance and protects against wear and tear


  • Less durable than other sealers, it may require reapplication every few years
  • Not as effective at preventing moisture penetration as penetrating sealers

3. Epoxy Coatings

Epoxy coatings are a heavy-duty sealer option that creates a thick, durable layer on the surface of your concrete basement floor. These coatings are highly resistant to moisture, chemicals, and abrasion, making them ideal for high-traffic or industrial basement spaces.


  • It provides a strong, durable protective layer
  • Resistant to moisture, chemicals, and abrasion
  • It can create a smooth, glossy finish


  • It can be more challenging to apply than other sealers
  • It may require professional installation
  • It can create a slippery surface when wet

4. Polyurethane Coatings

Polyurethane coatings are similar to epoxy coatings, offering a thick, durable layer of protection for your concrete basement floor. However, these coatings are more flexible than epoxy, making them less prone to cracking and chipping.


  • Durable and long-lasting protection
  • Resistant to moisture, chemicals, and abrasion
  • More flexible than epoxy coatings, reducing the risk of cracking and chipping


  • It can be more expensive than other sealers
  • It may require professional installation
  • It can create a slippery surface when wet

How to Seal Your Concrete Basement Floor

Step #1: Prepare the Surface

Properly preparing the surface is essential before applying a sealer to your concrete basement floor. This includes:

  • Cleaning the floor: Remove any dirt, debris, and grease from the surface using a broom, vacuum, or power washer. Make sure the floor is completely dry before proceeding.
  • Repairing cracks and holes: Fill any small cracks or holes in the floor with a concrete repair product or epoxy filler. Allow the repairs to dry and cure according to the manufacturer’s instructions.
  • Etching the surface (if necessary): Some sealers, such as epoxy coatings, require etching the concrete surface to ensure proper bonding. Follow the manufacturer’s recommendations for etching and rinsing the floor.

Step #2: Choose the Right Sealer

Select the best waterproof sealer for your specific needs based on durability, appearance, and budget. Carefully read the manufacturer’s instructions and recommendations for application and drying times.

Step #3: Apply the Sealer

Once the surface is prepared and you’ve chosen the appropriate sealer, follow these general steps for application:

  • Ensure proper ventilation: Open windows and doors for adequate airflow during sealing.
  • Mix the sealer (if necessary): Some sealers require mixing before application. Follow the manufacturer’s instructions for proper mixing ratios and techniques.
  • Apply the sealer: Using a roller, brush, or sprayer, apply the sealer evenly to the concrete basement floor. Make sure to cover the entire surface and avoid puddling or pooling.
  • Allow the sealer to dry: Follow the manufacturer’s recommended drying times between coats (if multiple coats are required) before allowing foot traffic on the surface.

It’s worth noting that concrete walls may also need sealing if your basement has a poured concrete wall. Choose a waterproof sealer approved for use on walls and follow the manufacturer’s instructions for application.

Step #4: Allow the Sealer to Cure

After applying the sealer, allowing it to cure properly is essential. This ensures the sealer bonds effectively with the concrete and provides the desired level of protection. The curing time varies depending on the type of sealer used and the environmental conditions, such as temperature and humidity. Refer to the manufacturer’s instructions for specific curing times and guidelines.

Do Sealers Trap Moisture in the Concrete Slab?

A basement slab sealed with a moisture barrier is designed to protect the concrete from water seepage. However, some sealers can trap moisture inside the slab and cause mold or mildew growth. This is why you must choose a breathable basement sealer that allows moisture to escape from the slab without entering your home. If you want added protection against moisture, consider using two coats of sealer and paint the surface with epoxy or latex paint. Doing so will help keep water from getting through while still allowing vapors to escape, preventing trapped moisture damage.

It’s also important to note that sealing a basement slab does not guarantee that water won’t enter your home in the event of flooding, as floodwaters can rise high enough to go around the slab sealer. If you live in an area prone to flooding, it’s a good idea to have your basement waterproofed to provide extra protection.


1. Should I seal my basement floor before finishing?

Yes, it is strongly recommended that you seal your basement floor before finishing. This will help protect the surface from moisture and mold growth and make it more comfortable to walk on. Sealing your basement floor can also make the finished surface last longer by providing an extra layer of protection. Additionally, sealing your floor before finishing will save you money in the long run since it can extend the life of your floors and reduce maintenance costs.

2. Can you seal old basement floors?

Yes, you can seal old basement floors with various materials. Epoxy coatings are a popular option for sealing concrete basement floors. These coatings provide a durable, waterproof barrier that will protect your floor from water damage and mold growth. Another option is to use paint-on or roll-on waterproofing membranes. These products create an effective barrier against moisture and come in several colors to match any décor. Additionally, there are various types of vinyl sealants available that can be used to protect your floors from moisture and provide extra insulation as well.

3. How much does hiring professionals to seal my basement floors cost?

The cost of hiring professionals to seal your basement floors will depend on the size of the area, the material being used, and other factors. Generally, you can pay between $1-$3 per square foot for professional basement floor sealing services. However, it is important to note that this cost can vary widely depending on the scope of work required. It is always best to get multiple estimates before deciding so that you can find the most affordable option for your project.

4. Can I seal my basement floors myself?

You can seal your basement floors with the right materials and tools. However, you must remember that this type of work requires expertise and should only be done with proper safety precautions. Sealing your basement floor is a complex job that requires precision to ensure it is properly sealed and protected from moisture and mold growth. If you are unsure about the process or feel uncomfortable doing the job yourself, hiring professionals with experience in this type of work is best.


Sealing concrete floors of a basement is a wise decision that offers numerous benefits, including protection against moisture, mold and mildew growth, enhanced durability, and improved aesthetics. Understanding the various types of waterproof sealers and following the proper application techniques can ensure a successful sealing project that will keep your basement dry and comfortable for years. So, give your basement the protection it deserves with a high-quality waterproof sealer!

Don’t know how and where to start? Call us now, and let us help you create the perfect sealed basement floor. We have the experience and expertise to get the job done right.

Leave a Comment

Your email address will not be published. Required fields are marked *