Unvented Roof Systems

These roofs have some pros and cons as explained in the article.

Unvented roof systems.

A system most likely to be found in newly built homes. Unvented roofs have a number of advantages. An unvented roof assembly is constructed without any ventilation and is fully sealed on all sides and filled with insulation. As a result unvented roofs have become popular in homes with feature dense roofs think multiple skylights dormers and other aesthetic flourishes.

In cold climates insulating sheathing must be added exterior to the roof sheathing to prevent condensation on the underside of the roof sheathing. When properly installed unvented roofs perform well and cause no excess. Enhancing roofing material life span by reducing sheathing temperature. Unvented roof systems where the 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.

Sc historically typical construction of homes in canada and the us have vented attics between the ceiling of the interior space and the roof. Removing moisture from roof cavities structural members sheathing and insulation. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. While unvented attics are gaining acceptance homeowners must realize their limitations including.

Unvented roof systems can be safely used in many different climates. Controlling ice damming by keeping the roof cold. The term hot roof is something of a misnomer as the attic space will only be a few degrees warmer than in a traditional roof. There are traditionally four main reasons for venting a roof.

Ventilation becomes more difficult the more complicated a roof s construction is. An unvented assembly can perform well but it s important to get the details right to avoid sheathing rot. However designers of compact roof assemblies must consider vapor permeance and arrangement of the roofing materials to produce acceptable hygrothermal performance and low. Unvented roofs vented roof.

Many local building codes do not account for non standard construction alternatives such as unvented attic assemblies.