The goal of tapered roof insulation systems is to reduce or eliminate the amount of ponding/standing water on the membrane when the roof deck does not provide adequate slope. Draining water in a timely and efficient manner minimizes the adverse effects that ponding/standing water can have on completed roof membranes. A properly designed tapered roof insulation system not only provides the positive drainage needed but also helps extend the life of the roof membrane. As more designers and roofing professionals understand the importance of positive drainage in good roofing practice for both new construction and re-roofing, the popularity of tapered insulation has increased dramatically.
Ponding water can be the greatest threat to a roofing membrane. It not only shortens the expected life of the membrane, potentially voiding the membrane warranty, but can also lead to more serious problems such as structural deflections of the roof deck and bacterial or unwanted vegetative growth on the roof.