How long does Flex Seal stay waterproof?

Author: Hubert Ernser  |  Last update: Monday, October 13, 2025

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.

Is Flex Seal a permanent fix?

It is also important to note that while Flex Seal may be a temporary fix for leaks and cracks, it is not a permanent solution and may need to be reapplied over time.

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 stop a water leak?

Flex Seal can be a temporary solution for a leaking water pipe, but it may not be a permanent fix. It works by sealing cracks and leaks with a waterproof coating, which can be effective for small leaks or drips. However, for larger leaks or significant damage, it's best to repair or replace the pipe properly.

How long does Flex Seal last on a leak?

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: USE Flex Seal LIQUID? *Tips & Tricks*

Will Flex Seal hold under water pressure?

Q: How much pressure will it withstand? A: Flex Seal will withstand normal hydrostatic water pressure such as rainwater, but it is not made to withstand extreme pressure.

How long does Flex Seal need to dry before rain?

Q: Can I apply it on a wet surface or when it's raining? A: It's always best to apply Flex Seal Liquid on a clean, dry surface free of grease and oil. If applied during heavy rain, some of the product may wash away. Therefore, we recommend applying it 24 hours prior to any heavy rain, hail or snowfall (if possible).

What is the most effective water sealant?

The best product for keeping water out is a waterproof silicone sealant. The silicone improves the quality of your sealant by upping both the flexibility and adhesion.

What will Flex Seal not stick to?

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.

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.

Why not to use Flex Seal?

Flex Seal Isn't Safe for Use Around Food or Potable Fluids

Even the Flex Seal manufacturer asserts that these products shouldn't be used near consumables. Having a product like Flex Seal leach harmful chemicals into your water supplies can have widespread consequences.

How do you keep Flex Seal from drying out?

To increase the life of your Flex Paste, store it in an air-conditioned, humidity-controlled environment.

Is Flex Seal good for roof leaks?

This product is most effective for small cracks and holes, particularly in areas that are not under constant pressure or load. For minor leaks, such as those around vent pipes or small cracks in flat or sloped roofing materials, FLEX SEAL might be a suitable solution.

Can you use Flex Seal in a shower?

Many people have had success using Flex Seal Aerosol to seal their shower tiles.

What is the strongest waterproofing?

POLYURETHANE

Polyurethane is considered one of the best waterproofing materials. It can be applied seamlessly and penetrates the surface deeply and evenly. Thus, the polyurethane membrane will fill in even the finest cracks in concrete, reducing its water absorbency capacity.

What is the best sealant to use in wet conditions?

Hybrid Polymers such as Everbuild Stixall are fantastic for use outside. They can literally be used while under water! Hybrid polymers are both a sealant and an adhesive, and have extra qualities due to mixing two or more chemicals together.

What is the best thing to stop a leak?

Silicone sealant: Silicone sealant is a versatile sealant that can be used on a variety of surfaces, including glass, metal, and plastic. It's ideal for sealing leaks in pipes, as well as around windows and doors.

Can you waterproof with Flex Seal?

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. Start by taping off the walls you will be waterproofing with blue painter's tape.

How long does Flex Seal take to harden?

Flex Seal will usually dry to the touch within 2-3 hours of application and fully cure in 24-48 hours. Dry time depends on the temperature, humidity, and thickness of the coating.

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.

How long will 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.

Previous article
What cookware does Gordon Ramsay use?
Next article
What are the three main types of roofing materials used today?