foam sealants

Foam sealants are used to air-seal holes and cracks with different sizes, though mostly used in medium openings, that is, in holes, cracks and penetrations between 1/4 inch (5 mm) and 3 inches (60 mm) wide.

Common non-foam caulks are typically used for smaller gaps and holes, while very large surfaces and penetrations are usually air sealed with rigid foams or sheet goods as plywood (see Air Barriers vs. Vapor Barriers).

Foam sealants are also great to get airtight-insulated solutions, and come with different properties.

Polyurethane foam Sealants

Sealing foam from Dow , the main foam sealant manufacturer Most foams are polyurethane-based, but that doesn't mean that they all have the same properties and uses. Namely, you should distinguish between high-expanding polyurethanes and non-expanding polyurethane foam sealants.

Expanding-polyurethane foam sealants involve two varieties: one to adhere directly to surfaces and other to apply in cracks.

Expanding-polyurethane is excellent to apply in rough surfaces and irregular cracks. This variety will easily fill the whole crack or the whole surface, despite possible irregularities.

Low-density polyurethane foam sealants aren't as strong and do not offer the same air-tightness.

foam Sealants application

Be aware. Use protective measures. Always wear gloves, protective glasses and proper clothing when using foam sealants. It will be painful if the foam sticks to any part of your body. Pay attention to the package instructions.

Foams and windows and doors

Foams are excellent for sealing holes and cracks around the exterior side of windows and doors, and to apply to cracks exposed to sun and moisture.

In case of deep penetrations, consider also the use of a backer rod (closed-cell material, typically sold in long coils with a quarter-inch to an inch in diameter). Backer rods provide the ideal backing for sealing, ensuring flexibility to caulks and foams.

Chimneys and high temperature…

To seal around chimneys, flue pipes and other structures associated to combustion you need high-temperature materials such as metal flashing and high-temperature foam sealants.