Can I use flex seal in my basement?

Author: Donnie Cruickshank  |  Last update: Tuesday, March 18, 2025

Flex Seal Liquid is thicker than paint and dries into a strong, rubberized coating. It can also help seal out air, water, and moisture and is chemical and mildew resistant - making it a great choice for your basement walls.

Does Flex Seal work in basements?

Flex Shot and Flex Seal Liquid are great options for attacking a basement wall leak.

Where should you not use Flex Seal?

We do not recommend using Flex Seal on foam. Some foams may react poorly with Flex Seal, and may warp or dissolve. We also do not recommend using it in situations where it is subjected to high heat or pressure (such as engine radiators) or gas tanks. We do not recommend the use of Flex Seal spray on vinyl.

How long does Flex Seal last on concrete?

Depending on the environment, coats added, and maintenance, many people have found Flex Seal will last for years without cracking, peeling, or losing any of its strength or sealing properties.

What is the best thing to seal a basement?

Use Hydraulic Cement: For larger cracks or holes, hydraulic cement is a good choice. It expands as it cures, creating a watertight seal that's effective for waterproofing basements.

How to Waterproof Basement Walls With Flex Seal Products

What is the cheapest way to seal a basement?

Which is the cheapest basement waterproof? The cheapest basement waterproofing method is typically applying a waterproof paint coating, which can cost as little as a few dollars per square foot for materials if doing it yourself. Caulking cracks and opting for interior solutions is cheaper than exterior excavation.

Can I seal my basement from the inside?

Seal/coat the interior of the walls with a suitable masonry waterproof product. When the paint dries, the sealant forms a watertight bond to stop water from seeping through. This is how you can waterproof your basement walls from inside.

What happens if Flex Seal gets wet?

Once dry, Flex Seal's watertight, rubberized coating can withstand water, heavy rains, snow, and more. Flex Seal can be applied to a wet surface or moist environment in the event of an emergency. However, it will always adhere better to a clean, dry surface.

Will Flex Seal stick to concrete?

Yes, you can use Flex Seal Spray on concrete. Flex Seal seeps into cracks and holes and dries to a watertight, flexible rubberized coating. Flex Seal can also be used on many other surfaces, including wood, metal, tile, masonry, fabric, glass, plastic, aluminum, porcelain, drywall, rubber, cement, and vinyl.

Can Flex Seal be used indoors?

Before using Flex Seal, make sure that you have a well-ventilated area. Your garage could be the perfect space (with the door open). Or you could use a room in your house with windows opened and a fan running. If you're more of an outdoor kind of guy (or gal), try your backyard.

Is gorilla seal as good as Flex Seal?

It's not like Flex Seal, which coats in a thick, black, rubbery, “substance”. Gorilla Seal sprays on clear, wet, soaks in, and is for all intents and purposes “invisible” when dry. More importantly – it works! There were a number of rainy days in the week after installing the coated wood into the bay window frame.

Is Flex Seal a permanent fix?

Flex Tape is a temporary, emergency repair and is not meant to be a permanent fix.

Can I put drylok over Flex Seal?

Flex Seal Liquid is not compatible with Drylock.

How much does 1 gallon of Flex Seal cover?

However we have Flex Seal Liquid that comes in Gallons each gallon covers approximately 150 square feet and depending on how thick you roll or pour it you will need 3-5 gallons on your Shop roof.

Why is the top of my basement wall leaking water?

Water leaking through walls may result from plumbing issues, clogged gutters, faulty irrigation, or improper drainage. Common signs include expanding stains, peeling paint or wallpaper, mold in dry areas, buckling ceilings, dripping sounds, and wet spots.

Is Flex Seal really waterproof?

Flex Seal floated our boat, and Teddy stayed dry. But with other uses, we hit rough seas. It took three coats of Flex Seal to plug the pipe holes, and larger holes blew out under water pressure. Even three coats didn't seal vertical sections of our gutter's end caps and joints: The product dripped down.

Can you use Flex Seal to seal a basement?

Basement Waterproofing

Flex Shot is often used alongside Flex Seal Liquid to provide a superior water shield. For a thorough how-to with step-by-step instructions on waterproofing your basement, check out Flex Seal Liquid for Basement Waterproofing.

How long does Flex Seal last?

Q: How long will it last? A: Depending on the environment, coats added, and maintenance, many people have found Flex Seal will last for years without cracking, peeling, or losing any of its strength or sealing properties.

How to seal a leaking basement floor?

5 Steps to Waterproof Your Basement Floor
  1. Clear out the basement. The first thing you'll want to do is clear the basement of your belongings, so you have room to work. ...
  2. Clean the floor. ...
  3. Check for radon leaks. ...
  4. Fill in the cracks. ...
  5. Apply waterproofing coating.

Can Flex Seal be removed after it dries?

If the Flex Seal is still wet, it can be removed with a dry cloth or paper towel. If the Flex Seal is cured/dry, it can be removed with acetone, denatured alcohol, or mineral spirits. When using solvents to remove Flex Seal, make sure to read the instructions and follow all safety precautions.

What happens if you paint over Flex Seal Liquid?

Flex Seal Spray can then be painted over with almost all commercially available paints and urethanes. Flex Seal Liquid cannot be top coated with anything other than Flex Seal Liquid, however, you can add as many coats as you like. Just allow Flex Seal Liquid to fully dry between coats.

Is it a good idea to seal your basement floor?

Absolutely! Sealing your basement floor offers numerous benefits: – Protection: It guards against moisture penetration, which is crucial in preventing mold and mildew. – Longevity: A sealed floor is more resistant to wear and tear, helping to extend the life of the concrete.

What are the disadvantages of basement waterproofing?

Exterior basement waterproofing has a few downsides, though.
  • Cost. It's a more involved process that requires digging up your yard, which is expensive and time-consuming.
  • Damages landscaping or hardscaping elements. ...
  • Not serviceable.

Should you waterproof your basement?

Deciding to waterproof your basement is a key step in making your home a safer, healthier place. It will help you avoid insect infestations and potentially dangerous mold, as well as protecting your home's structure from damage.

Previous article
How long do you drain a water heater for?
Next article
How to sanitize well water?