Unvented Low Slope Roof

However architects of these compact roof assemblies must consider vapor permeance and arrangement of the materials to produce acceptable hygrothermal performance and low risk of condensation in the resulting conditioned attic space.

Unvented low slope roof.

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. 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. Whatever method is used the amounts of insulation must achieve r values mandated by local codes. Like a wall that is severely out of plumb an unvented roof has insulation packed into the framing cavities aligned with the sheathing.

Drying of unvented roofing assemblies is by definition only provided to the interior. In unvented flat or low slope roofs with parapets perform a full flood test to ensure leak free installation of roofing membrane. The insulation can go below the roof deck above the roof deck or both. 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.

If the upper edge of a low slope shed roof intersects a vertical wall the most logical approach in my opinion is to detail the roof as an unvented roof. Low slope and steep slope unvented roof systems i e.