Roof coatings made with acrylics, urethanes or asphalt soften under the stress of ponding water or snowpack. Eventually, these roof coatings will bubble and peel away from the substrate, leaving your roof vulnerable to leaks, rot, and decay. However, GacoRoof’s 100% silicone formulation is designed to stand up to whatever the elements dish out. Silicone will withstand areas of ponding water without softening, bubbling or peeling from the substrate. Acrylic, urethane and asphalt roof coatings decompose and wear away from the stress of harsh sunlight, UV rays, and freeze-thaw cycles.
Most samples of closed cell spray foam insulation have an R-value of 7 or greater. Open cell spray foam, which is acknowledged to have a lower density, has an R-value of 4 which still rates higher than other kinds of insulation. Spray foam can be evenly employed on a surface and even be inserted into hard-to-reach places to produce a tight seal over the area.
I am an Architect in Toronto. I am designing a new roof addition to a row house building. Because of existing conditions and the shape of the new roof. It may be easiest to use closed cell spray foam within the areas of the joists. My question is when spray foam is used in this situation do I need to worry about how the joist members may be thermal bridges? It is not common to provide a little bit of rigid insulation to protect the joist members? The additional layer of outboard insulation will require an extra layer of plywood above the insulation which will add to cost.