Roof Coating Blisters

Membrane systems are most susceptible to blistering because blisters are formed by voids between the plies or at the point between the substrate and the membrane.

Roof coating blisters.

Blisters may occur below or between ply sheets in a built up roof system at the roof coating interface with the roof surface or between coating layers when multiple coats have been applied to the roof. Bubbles across your foam roof will look like small or large rounded domes that stick up from the surface. This roof has way more blisters on it than normal. Foam roofs are made from spray foam polyurethane by mixing two different materials together.

Generally speaking unless its at a scupper or in a ponding area one broken blister is not an emergency. It is important to recognize the difference before proceeding. These bubbles are often referred to as blisters and they are a sign that moisture has reached the inner layers of the polyurethane material. When you coat a roof you seal moisture inside the substrate.

Most blisters are caused by the same thing moisture. When the roof heats up due to the sun or internal building heat this moisture evaporates and becomes water vapor that expands by up to 1300x its volume. Loss of gravel granules or another surfacing membrane deterioration blisters in seams which have reduced lap coverage blisters that have breaks that can. Once broken water is more likely to get under the coating or leak into the roof.

Blisters may be filled with water or air. They are usually formed by the pressure of moisture beneath the surface of from lack of adhesion causing dry spots.