While blisters or bubbles on a rubber roof can be unattractive, they won’t necessarily cause the membrane to fail. If you are still troubled by their appearance, however, there are some things you can do. First, it helps to understand what might have caused the bubbling in the first place.

A Common Issue

Known in the roofing business as EPDM, rubber roofing has a lot of benefits and only a few drawbacks. Not only is the material itself cheaper than many other choices; the product is very lightweight, and installation is relatively simple and easy. This helps reduce labor costs, resulting in a less expensive overall product.

Rubber is also very durable. Most EPDM roofs are laid as one piece, which means there are few – if any – seams, depending on the roof’s layout. Fewer seams mean fewer places for water to leak beneath the roofing and destroy the home. Since the rubber is glued into place, it negates the use of heat, which can adversely impact a homeowner’s insurance policy. Because modern rubber isn’t susceptible to ultraviolet rays, a properly installed roof can last five decades or even longer.

Unfortunately, rubber roofing can also develop bubbles, which occur for a variety of different reasons.

How Do Rubber Roof Bubbles Develop?

Vapor from Bonding Adhesive

Installers use contact bonding adhesive to affix the EPDM membrane on upstands and all around the roof deck perimeter. Because the adhesive has a solvent base, it should be allowed to “gas off” until it is dry to the touch. If the membrane is bonded into position too early, bubbles or blisters will develop beneath the membrane due to trapped vapor from the adhesive.

These bubbles usually aren’t particularly severe and will dissipate over a relatively brief period of time, since EPDM membranes are partially breathable. You can accelerate the process by adding an even amount of weight to the affected area. In severe instances where the adhesive hasn’t been allowed to adequately dry, the membrane might need to be peeled away and re-bonded.

bubbles in rubber roofing

Trapped Air

This kind of bubbling often occurs with warm deck roofs where the EPDM is fully bonded directly onto the insulation or onto a timber deck. If the structure beneath the insulation is somewhat damp or the underlying boards are fitted with big gaps, the moist air will remain trapped. As the sun warms the roof, it will begin to appear as bubbling along seams. The EPDM membrane will often contract back into its normal position after the sun sets and the temperature cools.

When installing the warm deck insulation, it’s important to make sure the underlying roof structure is dry. It’s also important to make sure the insulation boards are tightly fitted together. Any large gaps should be filled with some type of expansive foam adhesive to keep the trapped air from lifting the rubber membrane. If you plan to install a timber deck atop the insulation, consider installing an inexpensive Visqueen membrane beneath the timber deck. This will help keep the expanding air from causing the membrane to lift.

What You Can Do

Unfortunately, if bubbles are appearing on your rubber roof, there’s not much you can do on your own. In most cases, this is a sign of improper installation and will require a professional to remedy the problem. This is yet another example of why it’s so important to hire a reputable roofer to install your roof.

All too often, inexperienced roofers claim to have the required expertise to properly install EPDM roofing, when they actually have limited experience working with the product. There are lots of different types of roofing materials. Just because a contractor claims to be a roofer doesn’t mean he or she has spent a lot of time installing rubber roofing.

With this in mind, it’s important to check a contractor’s credentials before you hire them to install your roof. If you are noticing signs of bubbling, it’s best to call a professional to come and look at the problem, since do-it-yourself remedies can lead to costly leaks that can result in thousands of dollars in damages.

Need a new roof or help repairing flaws or damage? A to Z is ready to help. We’ve spent decades developing a widespread reputation as one of Colorado’s leading roofing contractors by providing reliable, expert workmanship and honest, courteous customer service. Contact our team to learn more.