Unvented Low Slope Roof

Unvented low slope roofs are never designed to dry to the exterior because low slope roofing membranes are vapor barriers.

Unvented low slope roof. Because the attic space is now inside the thermal envelope blowing a little heat up there is not like throwing twenty dollar bills out the window. Like a wall that is severely out of plumb an unvented roof has insulation packed into the framing cavities aligned with the sheathing. In unvented flat or low slope roofs with parapets perform a full flood test to ensure leak free installation of roofing membrane. Drying of unvented roofing assemblies is by definition only provided to the interior.

The insulation can go below the roof deck above the roof deck or both. While this fact adds some risk to these assemblies compared for example to a traditional vented unconditioned attic with asphalt shingles this type of roof is very common. Insulation and air barrier are applied directly to the underside of the roof deck are common in applications where designers are seeking cost effective and energy efficient roof assemblies. Whatever method is used the amounts of insulation must achieve r values mandated by local codes.

Five ways to insulate an unvented low slope roof of the various methods to insulate a shallow roof applying insulation to the exterior is easier than working in a space with limited access. Low slope and steep slope unvented roof systems i e.