Low Slope Metal Roof Details

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.

Low slope metal roof details.

These critical junctures account for the majority of roof leaks. Low slope metal roofs have simple geometries and are easier and less expensive to install that medium to steep slope roofs. Available in 12 16 and 18 widths tite loc and tite loc plus panels can be produced in 22 and 24 gauge steel or 032 and 040 aluminum. 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.

Minimum metal roof slope depends on the roof profile building design climate and site location. Because of the shallow height of the undulating ridges of the 5v and corrugated profiles and the use of exposed metal fasteners to screw the metal to the roof deck they are limited to a slope that will shed rain quickly. The most critical application points on low slope roof systems are at flashings penetrations and accessories. But the taller profiles like standing seam and pbr shown below can be installed on roofs with as low as 1 4 or 1 2 in 12 pitch.

Problems at these points typically arise from improper application methods and the use of inappropriate or incompatible materials. It is important to note structural metal panel roof systems can be used for steep slope roof assemblies too. Another approach is to build a cupola or ventilated doghouse in the middle of the low slope roof an approach championed by joe lstiburek. The panels have been designed for application over a wide variety of substrates on roof slopes as low as 1 2 12 pitch.

Structural metal panel roof systems can be used for low slope roofs because of their hydrostatic or water barrier characteristics. That includes soldered metal roofing or synthetic membranes. Low slope metal roofs require less material which reduces the overall load on the building s structure. 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.

Low slope roofs are not totally flat their roof slope generally ranges from 1 4 12 to 3 12. A typical low slope metal roof has at least 25 recycled content and at the end of its long useful life is 100 recyclable. Not only can low slope metal roofing contribute to the bottom line it can also contribute to leed credits which are awarded to buildings that use high recycled content and other green construction materials.