Unvented Roof Design

Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction.

Unvented roof design.

This document provides a brief description of different types of unvented roof assemblies and the benefits of unvented roof 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 roofs have a number of advantages. Sc historically typical construction of homes in canada and the us have vented attics between the ceiling of the interior space and the roof.

An understanding of heat air and moisture as well as the causes of condensation is critical in detailing unvented roof assemblies. Unvented roof assemblies are becoming an increasingly common construction alternative to traditional vented roofs. The optimum systems developed to date are dependent on the climate location. They are designed without ventilation openings and the attic is conditioned like the rest of the living space.

Unvented roof here again the choice of what insulation to use and whether to install it over or under the roof deck depends on the condition of the present roof the depth of rafters the r value you must attain and cost. Designs and houses with unvented roof insulation systems have also been developed and constructed in cold and mixed climates. An unvented superinsulated roof by martin holladay issue 224 deck for a thick roof rigid foam insulation installed above the roof assembly can create an energy smart roof. Unvented roofs unvented roofs are increasingly common due to design priorities.

Unvented roofs operate by the principle that venting is not necessary to control moisture accumulation. Unvented metal roof ted storm posted in energy efficiency and durability on april 27 2011 09 53am in the process of construction currently have a standing seam metal room installed over synthetic felt over osb. Potential pitfalls to avoid include. Ventilation becomes more difficult the more complicated a roof s construction is.

Over the past five years several unvented roof insulation systems have been developed by the building science consortium for use primarily in hot dry and hot humid climate zones.