Leak Seal vs. Flex Seal: Which is the Better Fix?

Gaps, cracks, and holes on your RV roofs and walls are more than just minor inconveniences. They cause SERIOUS damage to both your home AND bank account.

The perfect fix? Liquid rubber sealants like the Rust-Oleum Leak Seal and Flex Seal.

Today’s review is all about Rust-Oleum Leak Seal vs. Flex Seal, the best sealing products in the market. Which is better and which one should you use?

Find out as we break each of them down!

Are Leak Seal and Flex Seal the Same?

Because it’s always the small things that get in the way the most, leaks worsen and lead to major problems overtime, which is why they need to be repaired immediately and efficiently.

Both Rust-Oleum Leak Seal and the American favorite, Flex Seal, are excellent choices for seal leaks as they are easy-to-use, durable, and inexpensive.

The liquid formulations dry quickly in order to fill holes and to provide a firm-yet-flexible protection against moisture and rust on a number of surfaces.

Simply spray the can of rubber sealant on the crack of your RV roof, and you’re good to go.

End of the story, right? NO. That’s where you’re wrong.

You see, while both products are designed to seal in leaks, they are NOT the same.

This may be confusing for a lot of people, and we don’t blame you. Being used as sealing tapes or in spray cans, they are similar in a lot of ways.

HOWEVER, Flex Seal and Leak Seal uniquely cater to specific purposes and aren’t made of the same stuff.

What Is Rust-Oleum Leak Seal?rustoleum.com

Leak Seal is a convenient spray for treating cuts, breaks, and leaks with its rubberized protective utility coating. It can be used on:

  • Bitumen roofs
  • Gutters
  • Drains
  • Exterior walls
  • Chimney edges
  • Windows

It has a semi-gloss finish that’s 100% water-resistant and adheres to almost any surface.

The Rust-Oleum sealant can easily coat and fix any small to medium-sized cracks and holes, not more than 1/8” in diameter.

Also, it comes in two types: the Regular Leak Seal, which is the spray type, and the Leak Seal Brush, a liquid sealant.

For the regular Leak seal, Rust-Oleum sells them in two sizes: 11 oz and 12 oz.

Meanwhile, the Leak Seal Brush is available at 8 oz and 30 oz.

Regardless, the products work in the same way with the same formulation, only that the spray gives you better precision control.

What Is Flex Seal?flexsealproducts.com

On the other hand, Flex Seal is a super strong rubberized sealant that keeps out air, water, and moisture. The product is meant for:

  • Concrete and asphalt repair
  • Home and RV roof repair
  • RV and motorhome weatherizing and repair
  • Outdoor ponds and bird baths construction

Compared to the Rust-Oleum Leak Seal, Flex Seal is much more suitable for heavy-duty use and even works on glass and asphalt materials.

Flex Seal comes in both liquid and spray types, in a variety of sizes:

  • Flex Seal Spray: 14 oz and 17 oz.
  • Flex Seal Liquid: 16 oz, 32 oz, 1 gallon, and 2.5 gallons.

FUN FACT: You might know the brand, Flex Seal, from this viral meme.

SO, which is better for RV owners? Is there a clear winner?

Let’s begin our in-depth investigation!

What’s the Difference?

OK, now that’s loud and clear, the next question is: “how are they different?”

For this Rust-Oleum Leak Seal vs. Flex Seal comparison, we will be looking at the products based on the TOP things to consider when purchasing a liquid sealant:

  • Material Compatibility
  • Application Method
  • Durability
  • Curing Time
  • Painting Over
  • Available Colors

Leak Seal vs. Flex Seal: Material Compatibility

The first order of business in the Rust-Oleum Leak Seal vs Flex Seal review is looking at how well the sealing products work on different materials and surfaces.

#1 Compatible Surfaces

You can utilize either of the sealants on a wide variety of surfaces such as:

  • Wood
  • Metal
  • Glass
  • Copper
  • Aluminum
  • Tile
  • Masonry
  • Dry wall
  • Rubber
  • Cement
  • Fabrics

They even work on certain types of plastics and vinyls, as long as the Rust-Oleum and Flex Seal products are NOT exposed to gas or any harmful chemicals. Why?

The flexible seal will break down and dissipate, which means that you CAN’T use Rust-Oleum and Flex Seal on gas tanks and oil containers.

By seeping into the surface holes and cracks, it prevents moisture penetration and further leaks―so much so that both the Leak Seal and Flex Seal liquid rubber sealant spray and brush can be applied over a caulking job.

AND, yes, you can use the two products to fill in the gaps of your RV roof and even your motorhome’s toilet bowl.

Since the surfaces Flex Seal and Leak Seal are well suited with most materials, you won’t have a hard time applying it, given that you’re working on COMPATIBLE surfaces.

#2 Water Resistance

Then, how about wet surfaces like water barrels?

A common question that often gets asked is: “do both Rust Oleum and Flex Seal work on a wet surface?” The simple answer is yes.

They are 100% waterproof.

Although, be warned. Waterproof doesn’t always mean it holds up well.

A point to consider for RV owners when buying a spray sealant or any other sealing product is how much pressure can it withstand.

  • The Flex-Seal spray will withstand a normal hydrostatic pressure like that of rainwater, but it’s not designed for extreme pressure.
  • The same goes for the Rust-Oleum Leak Seal. It can handle up to 16 PSI which slightly one-ups its rival, BUT not by much.

Though, don’t get us wrong. The sealants are still water-tight and flexible enough to endure the moist environment and the rain, just NOT continuous submersion in water.

Basically, you can only use the rubber sealants to prevent leaks in water containers from the outside but NOT on kitchen sinks or any surface where water continually pounds.

In terms of wet surfaces resistance, again, the Rust-Oleum Leak Seal vs. Flex Seal are at par with one another.

#3 Food Safe

Finally, if you’re concerned whether Leak Seal and Flex Seal are food safe or not.

They AREN’T.

Unless you want serious consequences, NEVER apply Rust-Oleum Leak Seal and Flex Seal products on any drinking water or food containers. These include:

  • Fish tanks
  • Rubber Maid food containers (or any storage box where food is kept)
  • Water bottles

The liquid rubber sealants are ONLY food safe and plant safe once it completely dries.

Leak Seal vs. Flex Seal: Durability

Durability is the make-or-break factor for RV owners when looking for the perfect flexible sealant.

  • “How long do the products last?”
  • “Does Flex Seal work the way it’s supposed to? How about Leak Seal?”
  • “Which is more suitable for indoor and outdoor use?”

We’re sure you have these in mind. And they’re great questions to ask.

The only problem? There’s not one straight answer.

In the battle of durability, the difference between Rust-Oleum Leak Seal vs. Flex Seal is very apparent, especially with weather resistance.

#1 Temperature Resistance

In terms of strength, Flex Seal is tougher and thicker than the Rust-Oleum Leak Seal.

Its consistency is chunkier than the traditional spray paint, so it adheres to the surfaces of your recreational vehicle better.

BUT, there’s one trade-off.

Versus Leak Seal, Flex Seal is quite vulnerable to extreme temperatures. When it’s too hot or too cold, the product will peel off and disintegrate.

Once this happens, you’ll have to re-apply multiple coats, which is INCONVENIENT to do especially when you’re on the move.

Although Phil Swift, owner of Flex Seal, swears that the liquid rubber sealant expands, stretches, and stays flexible during the winter cold and the summer heat, between -80 to 350 degrees Fahrenheit, customers do NOT agree.

On the other hand, the Rust-Oleum Leak Seal is found to be the better outdoor solution. The formula is UV resistant and can hold up well during both cold and hot weather.

It has a solid performance as long as it is applied on a DRY surface. Beyond that, there isn’t anything to worry about.

Overall, Flex Seal is well suited for an indoor fix, while Leak Seal is for the outdoors, coming in perfect for RV roofs and the likes.

#2 Shelf Life

Because the sealing products are a great bang for the buck, you can store and stash them away for a very long time.

Flex Seal has a shelf life of 2 years when it’s properly sealed with a cover. Whereas, the Rust-Oleum Leak Seal has a longer shelf life of 5 years.

Leak Seal vs. Flex Seal: Application Method

The best thing about using liquid rubber sealants is you can easily do it by yourself.

In this criteria, there is no difference between the application method of the Rust-Oleum Leak Seal vs. Flex Seal. The process is the same for both of the products as instructed below:

  • Remove dirt and area to be coated. Make sure the treated surface is completely DRY before you apply the Flex Seal or Leak Seal or else the product will just wash itself off. You can use a wire brush or sandpaper to smoothen for the sealant to stick longer.
  • Mark up the gap so you can apply coating with precision. To keep things from becoming messy, cover the rest of the surface with plastic or fabric, so you won’t accidentally spray over it.
  • For brush sealants, dip, roll, and pour from the sealing containers to the surface.
  • If you’re using the Flex Seal Spray or the regular one, shake the can well for about 1 minute, pop open the lid, and give it a shot. According to Rust-Oleum, the spray needs to be done 8 to 12 inches away from the treated surface.

Once you apply Flex Seal or Leak Seal, it’s highly recommended to do multiple coats for the best results. 3 to 4 coats of either of the products would be good enough compared to one heavy coat.

And, just a hot tip, make sure to wait for the formula to dry after every coat if you want Leak Seal and Flex Seal to work the way they’re supposed to.

Customers who are impatient end up with a rubberized coating that won’t dry.

Leak Seal vs. Flex Seal: Curing Time

There seems to be a huge load of disparity in the Rust-Oleum Leak Seal vs Flex Seal curing time.

For the Leak Seal, whether it’s its regular or brush product, it easily dries up to touch in 20 to 30 minutes, a reasonable amount of time for a second and third layer of coating. It fully dries up in 24 hours.

On the flip side, Flex Seal products take and cure fully in 48 hours.

So, does this make the Flex Seal the slower drying liquid options between the two?

While it may seem like Rust-Oleum is the better choice for applying multiple coats, it’s good to keep in mind that air temperature, humidity, and thickness of the coating also play a factor in curing time.

Depending on how much coat you put in and if it’s exposed to air, the sealant may get cured earlier or much later.

Leak Seal vs. Flex Seal: Painting Over

So at this point, you’re gonna want to explore many DIY options for your RV.

If you’re all for the aesthetic, Leak Seal products will help make your dream design come true. Unlike Flex Seal, Rust-Oleum can be painted over without any issues.

The company’s products come in black, aluminum, white, brown.

Because Rust-Oleum Leak Seal is available in more colors, you can use latex-based paints oil-based paints for the sealants.

In contrast, Flex Seal isn’t designed to be coated in paint, and this goes for both its spray and liquid formulas.

The Rundown: Rust-Oleum Leak Seal vs. Flex Seal

Here’s a little summary of everything we’ve talked about:

  • Leak Seal and Flex Seal share similar material compatibility and water resistance. The sealants can be used on surfaces such as: wood, metal, tile, concrete, masonry, fabric, glass, plastic, aluminum, porcelain, dry wall, rubber, cement, some vinyls.
  • They should not be used to seal gas, harmful chemical containers, or anything you eat and drink from.
  • Flex Seal is thicker than Leak Seal, the only downside is that it’s more vulnerable to extreme weather.
  • Rust-Oleum has a key advantage over Flex Seal for outdoor sealing. The latter products are more suited for indoors.
  • Rust-Oleum sealants have a shorter curing time and longer shelf life than Flex Seal.
  • Leak Seal can be painted over, while Flex Seal can’t.

Leak Seal versus Flex Seal: Who is the Winner?

SO, who’s the winner?

WELL, we don’t want to be a spoilsport, but whatever you decide, they’re both GREAT options.

BUT, if you’re looking for something that’s more flexible, go with a Flex Seal.

For long haul trips in the great outdoors, Leak Seal is up for the job and are great Flex Seal alternatives.

Liquid rubber sealant is an immediate solution to gaps, holes, and cracks, so don’t sweat the small stuff and let Flex Seal and Leak Seal deal with it.

Before setting out for your trip, don’t forget to grab a liquid rubber sealant and fill those cracks up!

Pick up some leak seal

Pick up some flex seal

2 thoughts on “Leak Seal vs. Flex Seal: Which is the Better Fix?”

  1. The core idea of RV camping is to get together with family members and create cherished memories. Create a memorable travelling experience and make your entire family involved. This is your trip do things you enjoy doing the most. Happy camping! Please don?t forget to read out my blog and give reviews.

  2. Instead of using ordinary sealants, I recommend using Liquid Roof. Liquid RV Roof is a one coat system for your RV. The result is customers saving labor costs and material costs since many of the other systems on the market require multiple coats and provide no warranty.


Leave a Comment