If your commercial building has a rubber roofing membrane now, you might wonder if it can be covered with foam roofing when you need a new roof. Your roof needs to be checked by a commercial roofing contractor to make sure your roof is suitable, but in many cases, foam roofing can go over a rubber membrane. Here's a look at how it's done.
The Method Depends On How The Roofing Is Attached
Rubber roofing can be adhered with glue, attached with fasteners, and ballasted. Each installation method requires a different approach when putting spray foam roofing on top of the old roof. Membrane roofing that's adhered with glue is fully adhered. This means the entire membrane is glued to the roof. In this case, spray foam roofing can go right over the old roofing after it's been cleaned.
Fastened membranes have screws applied along the seams, but the middle part of the membrane is not adhered to the roof. In this case, cover boards have to be put on the roof and then the spray foam can be applied.
Ballasted membranes are held down with gravel. The gravel has to be removed in order to apply the spray foam. When the gravel is removed, there is nothing to hold down the rubber membrane, so cover boards are put down over it and screwed to the roof to give the spray foam something to adhere to.
The Roofer Looks For Moisture Problems First
Just because foam roofing can be applied over rubber membranes doesn't mean it's always a good idea. A commercial roofing contractor has to check the roof first to make sure it doesn't have too much moisture damage. This can be done by using a thermal camera to look for wet spots or by taking core samples from the roofing.
If the roof has a lot of moisture damage, the roofer might try to talk you out of covering up the old roof and go with getting new roofing instead once the rotted areas of the roof have been repaired. You'll still be able to get foam roofing, but it will be applied to the roof as the first layer of roofing rather than cover up an old membrane.
If your old membrane roof only has a mild amount of damage, then spray foam roofing might be ideal since it coats the roof in a single layer that forms a watertight surface on the roof. The foam even covers old flashing and creates new flashing out of the foam. Plus, the foam can be applied in various thicknesses, and this allows the roofing contractor to create a small slope to correct drainage problems on your roof. A company like Burwell Construction inc might have more information for you.