HOW TO INSTALL SPRAYED POLYURETHANE FOAM
Installing Sprayed Polyurethane Foam is initially a very difficult process that takes years of practice. The only way to get better is to install foam over and over again. After practicing over and over again, an installer can hone his skills and it will eventually become a very easy process.
Depending on the condition of the existing roof surface, there is usually some sort of tear-off required before foam can be installed. This may mean vacuuming off rock, tearing off old foam, or removing metal panels. Once the tear-off is complete, it’s time to build the deck that the foam will be sprayed to.
Foam adheres to many surfaces, but the surface must be structurally sound. If your roof was in poor condition and tear-off was required, the metal deck may also need to be replaced to provide a structurally safe substrate. It is also common for ISO board to be laid down on top of the new metal, or in the flutes of the metal, to provide a perfectly flat surface for the foam.
Once the roof surface and deck have been prepped, all roof features such as drains, vents, pipes, AC units, and access holes that aren’t being foamed must be covered or removed. The foam will adhere to all of these features if they aren’t covered, and that’s a difficult mess to clean up.
And now for the tricky part. After covering these features and prepping the roof surface, the foam is applied through a spray gun that mixes two chemicals together at the nozzle. This is the first time these two materials come in contact with one another, and when they are combined a chemical reaction occurs which causes them to expand and harden. The foam comes out as a liquid, so it fits into all the nooks and crannies of the roof. It adheres to the roof, and then expands and fills every gap. This creates a seamless, monolithic roof surface that is extremely strong, well-insulated, and resistant to severe weather.
The Achilles heel of spray foam is the sun. UV rays eat up the foam and cause it to deteriorate rather rapidly. However, the application of an acrylic or silicone roof coating protects the foam from the sun and extends the life of the foam significantly compared to exposed foam. Every 10-20 years, the coating over the foam needs to be replaced to continue providing adequate UV resistance. As long as the coating is maintained, essentially nothing can damage the foam.
Spray foam that is properly installed according to these guidelines can be expected to last 30 years or more. As long as it is properly maintained and the coating is re-applied on schedule, foam is virtually indestructible. There are many spray foam roofs that were installed 30, even 40 years ago that are still in great condition today; a testament to the longevity of this system.