Roof Synergy

Here's a video of a Spray Foam Roof application. This roof has already been "prepped", and they are in the process of spraying the foam on to the roof. Foam is kept as two separate components, often referred to (in the industry) as simply "A" and "B". These two components are pumped through a heated hose, and they are combined with an applicator gun. Foam rises to a few thousand times its original size (millions of small air bubbles are created inside the foam, which is one reason it's such an incredible insulator). Due to the way foam expands, only an experienced applicator can create a really smooth surface. Of course, this becomes exponentially more difficult if the base surface is too rough (yes, it's obvious, but some people might overlook this). On a tear off, or new construction, generally something like rolled roofing is applied to the roof to create a smooth base layer to spray on the roof. Vents, skylights, AC units, pipes and other obstructions may also require special preparation in order to properly install a foam roof.



Foam is self flashing and requires no fasteners to securely attach to a roof. The only requirement is that the substrate is slightly rough (not perfectly smooth), and very clean. In order for the foam to adhere, the existing substrate must be thoroughly cleaned, and all loose dirt, rocks or other material must be removed. If there is substrate damage, and the existing roof is wet, sometimes a torch is used to completely dry out the surface. Sometimes, as requirements dictate, sections of an old roof must be torn off completely. This is much cheaper than making a mistake and foaming over a bad area which must later be torn off (foam can be difficult to remove--it is extremely rigid). Also, tearing off foam on an existing foam roof can result in a somewhat unsightly appearance. However, tearing off bad sections of a roof, or an entire roof in advance, allows for a smooth clean resulting SPF roof.

It's amazing how fast foam hardens and sets. It seems to only take about 1 minute to do this. Watching a highly skilled applicator is quite interesting as well. It takes skill to take a material that expands at a 1000:1 ratio and get a really smooth result. Products like paint are really forgiving--if it's twice as thick in some places, no one notices. But if foam is twice as thick, you're looking at a 4 inch vs 2 inch lump.

Some places like the edges of a roof, drains, and a few other areas often need to be trimmed.

I have noticed that having a perfect 80 degree day with almost no humidity makes it easier to get a really smooth finish. A smooth foam roof can still be produced in relatively poor weather (e.g. colder--let's say 60 degrees, but dry). If the applicator is skilled enough it's possible.

The real killer is humidity though. If the humidity is too high, the foam wont properly adhere to the surface--this can be evidenced by blisters. Blisters are not a sign necessarily that the foam was installed under poor conditions. A dirty surface, lack of proper venting, or other factors can cause blisters.

I have seen many foam roof installations, including 'older' ones--and I can from experience, a properly installed foam roof lasts the life of the building.