Low Slope Roof Construction Details

These critical junctures account for the majority of roof leaks.

Low slope roof construction details.

The roof system is defined as the roof membrane including surfacing and the roof insulation. The roof assembly is defined as the roof deck along with the roof membrane and roof insulation. That includes soldered metal roofing or synthetic membranes. By low slope roofing we mean any roof that is pitched at less than 4 inches of rise in 12 inches of run or 4 12 pitch.

Generic valley treatment details for metal panel roofs for low slope with and without substrates are included in the mbma metal roofing systems design manual chapter 12 metal roof details. Problems at these points typically arise from improper application methods and the use of inappropriate or incompatible materials. Low slope structural roofing generally used on roof pitches ranging from 12 to 3 12 consists of interlocking panels commonly called standing seam roofing that run vertically along the roof surface. Another approach is to build a cupola or ventilated doghouse in the middle of the low slope roof an approach championed by joe lstiburek.

These panels generally come with a painted mill finish or a clear acrylic finish. Roof assemblies with a pitch slope of less than 3 12 are considered low slope roofs. Regular asphalt shingles and standard skylights will work at pitches of 4 12 or greater but at lower pitches you have to use different materials. Low slope roofs are often referred to as flat roofs.