Does Flex Seal Work On Concrete? (Find Out Now!)

Ossiana Tepfenhart
by Ossiana Tepfenhart
Flex Seal produces some of the best adhesives that you can use with materials such as wood, glass, and plastic. Luckily, you can use Flex Seal on concrete, and 1 gallon can cover 150 square feet. Let’s explore the important factors in applying Flex Seal to concrete such as application, price, and coverage.

Flex Seal is a brand that people relied on for ages. It’s a brand that’s known for creating adhesives that lock out moisture, keep things glued together, and prevents damage from exposure to the elements. Unfortunately, every sealant has its limits. If you’re currently working on a concrete project, you might be curious about whether Flex Seal is a good choice for you.

Few, if any, sealants are as versatile as Flex Seal. Along with more common materials like wood, glass, metal, plastic, and ceramics, Flex Seal is also compatible with concrete. If you have a concrete project that needs sealing from the elements, you can use a sealant from this brand to protect it.

Though you can generally assume that Flex Seal will work with your project, it’s important to know what it can and cannot do. This guide will give you the scoop on what you should expect.

Do You Need Foundation or Basement Waterproofing?

Get free, zero-commitment quotes from pro contractors near you.

How Well Does Flex Seal Work On Concrete?

Like most other moisture-locking protective sealants, Flex Seal has certain degrees of usability that one can expect from it. When it comes to concrete, ceramics, stone, and wood, you can expect Flex Seal to work exceptionally well. The unique formula of Flex Seal is incredible when it comes to porous surfaces. This means concrete of all types will work fairly well.

Are There Any Materials That Are Not Compatible With Flex Seal?

Flex Seal is great for most projects, but not ones that involve rubber, plastics, or vinyl. A good rule of thumb to follow is that you shouldn’t use Flex Seal on a rubbery-feeling surface. If you intend on using the materials in question in areas of very high pressure and temperature, it’s best not to use Flex Seal. Try something else instead.

What Can You Use Flex Seal For When It Comes To Concrete Projects?

It’s important to remember that Flex Seal acts a lot like a super thick sprayable (or brushable) paint without the actual tincture. The thickness offers a lot of excellent perks, including:

  • A Smoother Surface. Flex Seal fills in gaps and pores, making it easier to get a smooth, touchable surface with concrete. Sometimes, Flex Seal spray is even used as a primer. Just take note, you can’t paint over Flex Seal Liquid. So if you need to seal stuff with liquid, get a color you like.
  • Crack Sealant. Is your concrete cracking up? Flex Seal can fill in the crack while keeping things flexible enough to move with changes in temperature.
  • Paint Sealant. Got a graffiti problem? Sealed concrete is easier to remove paint than unsealed concrete.
  • Moisture Protection. Want your concrete to look snazzy and avoid moisture cracks? This is the stuff. It’ll prevent you from removing rust stains on concrete for a long, long time.
  • Leak Coverage. Both Flex Seal Liquid and Flex Seal Shot can be used for basement wall leaks with great success.
  • Gluing Stuff. Flex Seal Glue is a hybrid between sealant and glue. Enough said.

How Do You Apply Flex Seal To Concrete?

Flex Seal comes ready to apply, right in the can. All you need to do is spray it on directly or use a paintbrush to apply it directly to the concrete item of your choice. To help you make the most of your use of Flex Seal, check out these tips below:

  • Apply your Flex Seal on a dry, clean surface. While you could try to do it on a wet surface, it’s far from ideal. Doing this can cause your sealant to dry unevenly or may cause your sealant to last for a shorter amount of time.
  • Do not dilute your Flex Seal. The reason it is as thick as it is, is for your benefit. While you may want to dilute it, this only attacks the quality level of the sealant.
  • Do not use Flex Seal on flooring or in vinyl pools. If you want to protect a concrete floor, you will need something more specialized. It’s best to look for a flooring-specific sealant or a pool-specific sealant. The reason why you shouldn’t try to use this stuff on underfoot surfaces is because it becomes very slippery when wet.
  • If you have a spill or a bad application, you have about 10 minutes to adjust the Flex Seal before it’s stuck in the shape that it’s in. You can use a putty knife, a scraper, a paintbrush, or even a tray to readjust things. On a similar note, you should make a point of readjusting quickly.
  • The best temperature range for application is between 50 to 80 degrees Fahrenheit. While Flex Seal has a remarkably large range of temperatures it can withstand, it’s best to keep things in a happy medium.

How Much Coverage Do You Get From A Gallon Of Flex Seal Liquid?

If you want to get a lot of coverage, Flex Seal Liquid is a great pick. According to the actual Flex Seal site, you can get up to 150 square feet of coverage from a gallon can of Flex Seal. This is enough for a 10 by 15-foot wall.

How Much Does Flex Seal Cost?

While Flex Seal remains a leader in the sealant industry, it’s not something that you can expect to be cheap. A gallon of Flex Seal costs around $90. So if you want to use this stuff, it’s important to budget a lot more than you typically would for sealant. The only thing that’s pricier that’s regularly used is radon sealant, which is almost double.

How Long Can You Store Flex Seal Before You Use It?

Like all other sealants, Flex Seal does not have an indefinite shelf life. When kept at a stable temperature in the can it’s been placed in, you can expect your Flex Seal to last for approximately two years.

How Long Does Flex Seal Last?

This all depends on the application and the material that you’re coating in sealant. Most projects will not need another coat of Flex Seal for a very long time. In fact, it’s safe to assume that a coat of Flex Seal will last for a minimum of 30 years in most environments. This remains true, even in outdoor areas.

How Safe Is Flex Seal?

There are multiple types of Flex Seal products, but all of them were designed with safety in mind. They are not toxic once they dry, nor are they flammable once they are applied. So, you can use them in environments where you know your pets and kids will stay. Since most of the product lines act as liquid silicone or rubber, you also do not have to worry about allergens.

Do You Need Foundation or Basement Waterproofing?

Get free, zero-commitment quotes from pro contractors near you.


Related Questions

How can you make your Flex Seal dry faster?

Dry times with Flex Seal are fairly long, which is why many people opt to speed things up through their own means. The most common way to make your sealant dry faster is to use a high-powered fan, a heat lamp, or to turn the air conditioner up to max.As long as you have some form of wind blowing around the sealant, you should see a faster dry time. Some people use a blow-dryer to speed things up, but this is not advisable since it can cause uneven drying. It’s better to stick to large-scale forms of ventilation.


How long do you have to wait before Flex Seal becomes waterproof?

If you were hoping to spray sealant on and have waterproofing in a matter of minutes, think again. Flex Seal needs to cure for at least 24 hours before it makes the surface it’s protecting waterproof. If you applied the sealant in a damp or wet environment, you may need to wait as long as 48 hours before you can spray water on the surface.


How strong is Flex Seal Glue?

People in search of a seriously strong glue may want to check out Flex Seal Glue. Commercials regularly boast that this glue can hold up to 1,000 pounds together with minimal problem. With that said, you probably should just bolt stuff down if you need to bind thousands of pounds together. It’s just more convenient, not to mention safer.

Read These Guides For More Ways To Use Flex Seal

Ossiana Tepfenhart
Ossiana Tepfenhart

Ossiana Tepfenhart is an expert writer, focusing on interior design and general home tips. Writing is her life, and it's what she does best. Her interests include art and real estate investments.

More by Ossiana Tepfenhart

Next