Vented And Unvented Roof Assembly

An unvented roof assembly is constructed without any ventilation and is fully sealed on all sides and filled with insulation.

Vented and unvented roof assembly.

In other words vented roofs may well be the best design for one home while an unvented roof will be a better solution for another home. Because the drying capacity of unvented roof assemblies is inherently lower than vented ones it is especially critical to control built in moisture during construction. They are designed without ventilation openings and the attic is conditioned like the rest of the living space. Sc historically typical construction of homes in canada and the us have vented attics between the ceiling of the interior space and the roof.

Moisture content in roof structure must be less than 18 prior to covering. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck. Unvented roof assemblies are becoming an increasingly common construction alternative to traditional vented roofs.

An unvented assembly can perform well but it s important to get the details right to avoid sheathing rot.