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Flat Roof Sealant: What Is The Best Sealant For My Flat Roof?

Sean Levine  |  October 25, 2021  |   |  No Comments

With many options and no one size fits all, choosing a roof sealant for your roof can be difficult overwhelming, but it's still not impossible. Flat roofs over the years have been built to serve both residential and commercial structures. While they can prove quite undaunted to the elements, they will finally get subdued, leading to many common flat roof problems like standing water, blistering, and alligatoring.

The best way to tackle these problems is to apply a sealant to your roof. But then, what is the best sealant for your flat roof? How can you spot the best product that will serve your roof?

Factors To Consider When Choosing A Roof Sealant


Every roof sealant has only one core purpose: to protect your roof and help you dodge unnecessary repairs. Other times, sealants are applied to fix minor roof problems. What do you want your sealant to do for you? Is it to protect your roof or fix minor problems? Do you need it to repair a leak before it becomes a major problem leading to roof replacement, or do you need it to protect your roof from standing water, moisture, deluge, and sun exposure?


There are two categories of roof sealants

  1. Solvent-based roof sealant
  2. Water-based roof sealant

Solvent-based roof sealant is thicker, harder to apply, and more expensive, but it has a longer life span than water-based roof sealant. As a rule of thumb, the thicker the sealant, the more resistance it carries and higher the lifespan. Solvent-based roof sealant has a strong, unbearable, and unhealthy smell for your nose. Therefore, you need a respirator before you can apply it to your roof.

Water-based solvent, on the other hand, is soluble in water. Therefore, it is lighter, easy to apply, and less expensive. And you don't need a mask or respirator to use it.

Types of Roof Sealants

Acrylic Roof Sealants

This is a type of roof sealant. It has a bit of moisture resistance and also deflects UV rays. Unfortunately, it has no waterproofing element. Therefore, even after its application, if continuous moisture and deluge happen, your roof is likely to develop standing or pooling water. That said, the acrylic sealant might not be the best for your flat roof.


This is also known as PU. It is popularly known for its ability to resist any moisture, whether it is rain, snow, and precipitation. However, it is not resilient to sun exposure. So you can only use it in areas where there is less sun and mostly moisture.


This is one of the best among them. Silicone has resistance against UV rays and moisture. That is, you can apply it on any roof and in any city you reside in. And while it may be quite costly, it is worth the money. When sealing a commercial building, the price may get higher as the size gets more extensive, but the quality and the aesthetic appeal make the price you'd be paying for a silicone coating seem like a steal.


This is also a great sealant. Like silicone, the rubber sealant can withstand both UV rays (Sun) and moisture (rain, snow, precipitation. It's usually in a thin-based water formula. It can be used on any flat roof. But it is cheaper than the silicone but never beats the silicone's sealant quality.

Sealant Tape

Sealant tape, unlike others, is not a water-soluble sealant. As its name suggests, it's a moisture-resistant tape that applies to your roof to repair leaks, seal cracks, and exposed roof layers and seams.

Top 4 Sealants For Your Flat Roof

Liquid Rubber Waterproof Sealant

This is a rubber sealant option. And as you already know, it can be used under any weather condition. This waterproof sealant can be used on any roofing material, whether flat or pitched. It has power, and it's unfriendly to standing water. It is also UV resistant, making it one of the best choices you can make.

And the great news is that you can apply it with a brush, roller, etc. And definitely, it's affordable and suitable for your budget.

Gorilla Waterproof Patch And Seal Tape

As the name suggests, it is a sealant tape product. It is usually used for small projects around or on your roof. If you don't want to buy a whole pack of sealants, you should go for this. It can be used to patch a leak, bond your flat roofs together, etc.

Rubber Seal Liquid Waterproofing Coating

This is a solvent-based sealant category as well as a Rubber type of sealant. It has many advantages and has been reckoned for its effectiveness in the sealant industry. Starting with:

  • It is highly moisture resistant; therefore, it prevents any form of standing or ponding water, leaks, etc.
  • It is also effective in solar reflectivity. It can withstand the heat from the sun. It reduces the energy your roof consumes and gives you a warmer and healthier environment,
  • It is available in diverse colors. And in a sunny climate, using the white color is very prudent as it is more effective in reflecting the sun.

Loctite PL S30 Blackproof And Flashing Sealant

As a flat roof owner, you should know that one of the common problems you are likely to encounter is failed or worn-out flashing, which can lead to leaking and blistering. In this case, even when you change the flashing, there is a high chance that the damaged flashing might create some gaps that even the new flashing cannot occupy.

Here is where the polyurethane sealant comes in. It restores the moisture and the resistance level of your flashing. And also serve as an adhesive by closing the gap between your flashing and your flat roof. If you are particular about your flashing, then this is your best choice.

You can get all these solution-based sealants on Amazon.

For more information, consultation about the best sealant for your flat roof, or any flat roofing services, including roof inspection, reach out to us at 68-38 Main Street #2 Flushing, NY 11367 (718) 489-4009 https://www.kingsqueensroofing.com/.

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