Roof leaks are a major concern for any homeowner. If you think you may have a roof leak, it’s important to act fast and get it fixed. But what if you’re not sure if you have a roof leak? Can spray foam stop roof leaks?

The answer is yes, in most cases, spray foam can stop roof leaks. However, there are a few things to keep in mind. First, you need to ensure that the leak’s source is located and repaired. Second, you must ensure the proper application of the spray foam.

Below, we go into more detail about using spray foam for roof leaks.

Can Spray Foam Be Used On the Roof?

Spray foam roofing has three components:

  • Granules
  • Silicone coating
  • Spray polyurethane foam

When applied, the foam expands by 30 times and reaches a 1.5-inch height. Since the Sun’s UV rays can deteriorate spray foam, the silicone coating protects the foam and provides a long-lasting seal.

A single coat of silicone is added first. After that, a second coat is added, which is embedded with granules. The granules provide walking traction and add strength to the roof.

If you have an existing roof system with stones or gravel, you’ll have to remove the old roof before applying the spray foam. Do note that you can only install a spray foam roof in 50-degree weather.

If you install spray foam in winter, the chemicals in the foam will freeze and not expand. It will cause the roof to collapse. Here are some roofs that you can install spray foam on:

  • Metal Roof: Most metal roofs come with crimped panels, leaving holes for air and water to enter the building. By applying spray foam to the roof, you can fill in those holes and create a seamless barrier.
  • TPO: If you have a TPO roof, you can use spray foam to fill in the seams and create a watertight barrier. Since TPO is slippery, you’ll need a cover board for the best adhesion.
  • EPDM: You can apply spray foam on three EPDM roof types: ballasted, mechanically fastened, and fully-adhered. If you have a fully-adhered roof, you can install spray foam on top of it directly if the roof has aged over five years. In the case of a mechanically-fastened roof, you need to install a cover board first. Lastly, if you have a ballasted roof, you must remove the rocks first. Then, install a cover board and follow it up with spray foam.

Can Spray Foam Stop Roof Leaks For Good?

Spray foam can provide an airtight and watertight seal, preventing roof leaks. Not only does it fill in gaps and cracks, but it also adheres to the roof surface, providing a long-lasting solution.

When installed correctly, spray foam can last for decades without any issues. It’s also resistant to high winds, making it an ideal solution for hurricane-prone areas.

What Spray Foam To Use?

When choosing between open and closed-cell spray foam for the roof, it’s best to go with the closed-cell version. Closed-cell spray foam has a higher R-value, meaning it’s better at insulating the building.

It also has a higher density, which makes it more resistant to water and air leaks. Some notable brands that offer closed-cell spray foam are Icynene and Roxul.

How to Stop Roof Leaks With Spray Foam

You can use spray foam to stop roof leaks in these steps:

Step 1: Find the Source

It’s imperative to identify and fix the source of the leak before applying spray foam. Otherwise, the leak will continue, and the spray foam will eventually fail.

The most common sources of roof leaks are holes, cracks, and gaps. Once you’ve found the source, repair it with tape or caulk.

Step 2: Prep the Area

After repairing the source, you need to prep the area for spray foam application. First, clean the surface with a power washer to remove any dirt, dust, or debris.

Then, use a putty knife to scrape off any loose paint or cracks. Make sure the surface is dry before proceeding to the next step.

Step 3: Apply the Spray Foam

Now, it’s time to apply the spray foam. For best results, use a closed-cell spray foam.

Start by wearing protective gear, including:

  • Respirator
  • Goggles
  • Long-sleeved shirt
  • Long pants
  • Gloves

When you’re ready, hold the spray foam can 8 to 10 inches away from the surface and start applying the foam. For best results, use a zig-zag pattern.

If you’re using a large can, it’s best to apply the foam in sections to avoid overfilling the area. After applying the foam, use a putty knife to level it out.

Step 4: Let It Dry

Spray foam cures quickly, so you don’t have to wait long for it to dry. In most cases, it’ll be dry within 24 hours.

Once it’s dry, you can apply a topcoat or sealant for extra protection.

Alternative Ways to Stop Roof Leaks

Besides spray foam, you can use these materials to stop roof leaks:

  • Roofing Cement: Roofing cement is a type of sealant that’s often used to repair cracks and gaps in the roof. It’s easy to apply, and it dries quickly.
  • Tar: Tar is another type of sealant to repair roof leaks. It’s best for small holes and cracks.
  • Roofing Tape: If you have nothing else on hand, you can use roofing tape to repair leaks temporarily. It’s not a permanent solution, but it’ll hold up until you can get a proper repair.

As mentioned earlier, spray foam application requires a high temperature. Plus, spray foam can be expensive, and the application process is time-consuming.

If all these are limiting factors for you, it’s best to use one of the alternatives listed above.

Some roof leaks are too big for DIY fixes. If the leak is coming from the chimney, vent pipes, or skylights, it’s best to call a professional.

It’s also a good idea to call a roofing contractor if the leak is severe or if you can’t find the source.

A professional roofing contractor will have the tools and experience to quickly fix the problem, preventing further damage to your home.


Evan has decades of experience as a project manager for large-scale commercial renovation home-building projects throughout the US. Currently, Evan runs a successful construction management company in Virginia.

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