Will flex seal stop basement leaks?

Author: Abigayle Barrows  |  Last update: Sunday, May 24, 2026

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

Does Flex Seal work for basement leaks?

The only sealing of basement walls that will actually work, is sealing them from the outside. And flex seal wont do well in that application.

What is the best product to stop water leaks in a basement?

Once the area is clean and dry, you can begin plugging any holes or cracks in the walls with hydraulic cement. This will prevent water from entering the basement. An excellent product for this purpose is DRYLOK® Fast Plug. In only three to five minutes, Fast Plug creates a waterproof seal on any surface.

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 way to seal a leaking basement?

Use Hydraulic Cement: For cracks, apply hydraulic cement to fill and seal them. This type of cement expands as it cures, making it effective for stopping leaks. Apply a Waterproofing Sealant: After the hydraulic cement has cured, apply a waterproof sealant or paint designed for concrete surfaces.

Does Flex Seal Work On Concrete?

How do I stop water from seeping in my basement floor?

How to prevent a wet basement
  1. Improve outside drainage. ...
  2. Install or replace sump pump. ...
  3. Add interior drainage. ...
  4. Protect against plumbing leaks. ...
  5. Install new windows and window well covers. ...
  6. Repair foundation cracks. ...
  7. Check roof for damage.

Can you waterproof a basement from the inside?

Interior basement waterproofing involves waterproofing basement walls from the inside. This way, the water that leaks into the basement is re-routed, before it can come in, out and away from your home. It is an effective waterproofing method and a much less offensive alternative to exterior waterproofing.

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.

Is Flex Seal a permanent fix?

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

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.

How do you permanently waterproof a basement?

Apply a Waterproof Coating

Masonry paint, epoxy paint, and acrolein elasticized paint are all highly water-resistant. Make sure the wall is clean, dry, and free of loose debris so the paint will stick, and apply it on a day with no forecasted rain. You'll usually need two to three thick coats for the job.

What is the cheapest way to waterproof a basement?

The least expensive basement waterproofing methods include grading soil away from your home, installing downspout extenders on your gutter system, and applying a waterproof paint on the interior of the foundation walls.

Why is my basement leaking after heavy rain?

Cracks in the foundation walls or basement floor can allow water from the ground outside to leak into the basement, especially after heavy rain when the hydrostatic pressure is greater. An interior sealant might be enough to fix basement wall leaks if the cracks are small and leakage is minimal.

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.

Which Flex Seal is best for concrete?

Flex Seal Liquid is optimal for sealing, repairing, and weatherizing concrete. It works by sealing out air, water, and moisture and is mildew, chemical, and UV resistant. You can either brush, roll, dip or pour the liquid directly onto the concrete surface.

How to fix basement leak between wall and floor?

The most common solutions are the DRY-UP baseboard or a drain tile system. Baseboard system – The baseboard waterproofing system is a method that channels water from the walls or holes that are drilled through cement blocks to a sump pump.

What is the lifespan of Flex Seal?

Answer. Flex Seal Clear's longevity can vary depending on the conditions and surfaces to which it's applied. Generally, it can last for several years when applied properly and used in environments that don't involve extreme wear and tear.

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.

What will Flex Seal not stick to on concrete?

I have used Flex Seal to close up cracks in concrete. However if the surface you apply the Flex Seal to is "granular" and flaking off, the Flex Seal will not stick to it. Keep in mind that Flex Seal is a coating, not a bonding agent.

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.

Can I put drylok over Flex Seal?

Flex Seal Liquid is not compatible with Drylock.

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.

How to fix leaky basement from inside?

To waterproof your basement from the inside, apply a high-quality masonry waterproofing product to the interior walls. Once the coating dries, it creates a strong, watertight barrier that prevents water from penetrating the walls. This method effectively seals your basement against moisture infiltration.

What is the most effective way to waterproof a basement?

Foundation crack injection is a highly effective basement waterproofing technique used to repair cracks in foundation walls and prevent water intrusion. It is a specialized process that involves injecting a sealant into the cracks, effectively sealing them, and creating a watertight barrier.

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.

Previous article
Why is my AC outdoor not working?
Next article
Can rubbing alcohol remove blood stains?