Unvented Roof Assembly

This is a mis interpretation of the code.

Unvented roof assembly.

If you don t want to use sips or nailbase there are four basic approaches. Four options for building an unvented roof assembly. Read all of r806 5 carefully. Unvented roofs operate by the principle that venting is not necessary to control moisture accumulation.

Insufficient fill below the impermeable insulation layer. It s not and so code doesn t require r value ratios. Monolithic continuous exterior insulation ci above structural sheathing. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck.

They are designed without ventilation openings and the attic is conditioned like the rest of the living space. Un ven ted roof ˌənˈven t əd ro of an unvented roof assembly is constructed without any ventilation and is fully sealed on all sides and filled with insulation. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. Figure 6 describes open cell spray foam as air permeable.

This document provides a brief description of different types of unvented roof assemblies and the benefits of unvented roof construction. Two potential unvented roof assemblies. If air gaps are present between insulation layers convection currents can significantly reduce the performance of the assembly and compromise durability. In some climates it requires a vapor barrier.

Unvented roof assemblies should be insulated either with air impermeable insulation rigid foam or spray polyurethane foam or with a combination of foam and air permeable insulation.