Low Slope

Low slope roofs are defined as roofs with a pitch of less than 2” per foot, however in the climate we are in, we choose to limit the slope to less than 4” per foot. Generally this type of roof system must be able to have water standing on it, but not leak through. It is preferable that they have at least a minimal slope so they drain, but the accepted standard is that they would be dry after 48 hours of drying weather after a rain event.

Rigid Insulation is commonly installed below low slope roof systems. There are a number of different types of insulation used, such as polyisocyanurate, expanded polystyrene, extruded polystyrene and wood fiber. A specific type may be required, depending upon the type of roof system installed on top of it, the deck type, or the desired insulation value that is measured in its “R” rating (thermal resistance). Tapered insulation can also be used to achieve slope of the final roof system.

These roof systems fall into two broad categories. The first is a single-ply system, which are comprised of a single layer of high performance, high-tech membrane installed over the roof. Common materials used for these systems are EPDM, TPO, PVC and other lesser-used materials. Flat lock, soldered seam metal roofs can also be included in this category.

The second category would be a built-up system. This system is comprised of multiple layers of roofing material adhered together to create a final roof membrane. These systems are typically created with bituminous materials.

The design and specifications of low slope systems must consider the deck type, insulation material, membrane and flashing details, slope and how they all fit together for a successful installation. Your Garlock-French representative will be happy to discuss all of the options to assist you in this decision.