Unvented Roof Unvented Cathedral Ceiling Insulation

In general closed cell foam is the best choice for unvented cathedral ceilings.

Unvented roof unvented cathedral ceiling insulation.

Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. This document provides a brief description of different types of unvented roof assemblies and the benefits of unvented roof construction. It is also one of the most expensive and most building inspectors will not allow it to be left uncovered for fire code reasons. Moisture problems in unvented or poorly vented cathedral ceilings are not uncommon especially in cold climates where water vapor can enter the joist space and condense on the underside of the sheathing in cold weather.

These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck. Four options for building an unvented roof assembly option 1. With an unvented cathedral ceiling it is critical to keep moist air and water vapor away from the roof sheathing where it can build up and lead to wood decay. The rigid foam will be fairly thick see sidebar how much insulation.

Foil faced iso board can be cost effective insulation for finished attics and cathedral ceilings.