These are examples of a 90 lb. granulated cap sheet known in the industry as torch-down roofing. This material was created for flat roof applications or very low slope roof systems that don’t have the required 4 and 12 pitch to install a shingle or a tile product. This product is ideal for flat roof systems and in the 20 years of TR Construction’s existence, we have found that most flat roof hot mop rock systems are being replaced by this granulated cap sheet system.
We prefer the modified torch-down system over the rock and tar system because the biggest problem we find with a hot mop tar systems with gravel on top is what happens over time is the gravel moves. Wind, rain, vibration, cats using the gravel as kitty litter, cable wires on top of the roof system which are moving and move gravel, are exposing areas of the membrane which decrease the life expectancy of the roof system.
These gravel rock roof systems are throughout San Diego on older homes. With the modified torch-down cap sheet; the embedded granules on the cap sheet protect the membrane from decreased life expectancy. Furthermore, a granulated cap sheet application is simply an easier system to track and fix potential leaks that might occur. The life expectancy on a torch-down product is 12 years. With our proper installation of this product you should have a sound flat roof system for over 12 years.
Should I Replace My Flat Roof?
Flat roofs are not usually repairable. On older San Diego homes, it is common to see flat roof hot mop rock systems where gravel has been applied over tar. Unfortunately, we have found that things like wind, rain, and vibrations move the gravel over time. This exposes the roof to the elements and decreases its life expectancy.
We recommend torch-down roofing for flat roofs. With this roofing system there are embedded granules on the cap sheet that protect the roof and increase the life expectancy. Also, it makes it easier to track and fix leaks. When installed properly, the life expectancy of a torch-down roof is 15 years.