Flat Roof

thumbz__flat_W_AC thumbz__Flat_with_wallThe standard material used on flat roofs is modified rubber. It is used on both residential and commercial applications with wood, concrete, or metal decks. We use Firestone APP180 modified rubber or GAF Rubberoid with a white granulated top surface over a self adhesive base sheet.


Ponding water is very damaging to the life of a flat roof. If you have a sag in the roof or it does not drain properly for another reason, you should consider adding slope. Our recommendation is an ISO tapered insulation system. It is 4’x4′ panels of rigid insulation with 1/4″ per foot of slope built into the panels. The first panel starts out at 1/2″ and rises to 1 1/2″ and so on. Therefore, on a flat porch that is 12 feet wide for example, you end up with 3 inches of added slope and 3 1/2″ thick at the back side. The ISO system has an insulation value of R6 per inch, providing the added benefit of insulation for the room below. It is fastened to the deck with screws of different lengths and 3″ washers. The black shown is self adhesive base sheet.

Tapered ISO