Roof penetrations and stress points
A roof penetration is anything that comes up through a roof or goes down through a roof to the interior of the building. This includes vent pipes from toilets, sinks, A/C duct vents, A/C curbs, electrical, drains, heat vents, swamp coolers, wall support brackets, skylights, building ventilation, roof access hatches, etc. The roofing around penetrations receive the most amount of stress. There are surveys stating that 80% of roof leaks occur around these types of roof penetrations. Having been in the roofing trade for over 25 years, experience has shown that may not be too far off.
Once common denominator observed almost all of the time and normal for the trade is the use of canned tars around these penetrations. These tars work well for the short term but have a tendency to dry out quickly and split away from the roof penetrations or flashing. This leaves an access for any water to get under the roof and eventually inside the building.
When the leak shows up inside, a roofer or building maintenance will put more can tar on the area and in time the tar drys out again with the crack or split reappearing and on it goes.
Commercial Cool Roof Systems does not use tar on any roof penetrations. An acrylic mastic is used instead which is like a white rubber. It is extremely flexible and does not dry and split out like canned tars. This white mastic outlasts any tars by at least 3 to 1. Another important part of our application is that we clean any old scaling and loose tar off the item that is going to be sealed. Having a good, solid contact with the metals or roofing is critical. In some case we use reinforcing fabrics to further strengthen the acrylic mastic. This acrylic mastic holds up extremely well to the sun’s heat and ultra violet rays. We use this standardly on all our cool roof systems and maintenance repairs.
There is not any real difference in material costs and the labor is about the same but the acrylic mastic lasts over 3 times longer which makes this a much less expensive option for you and holds up better under the stresses that occur around roof penetrations.