Unvented Roof Systems

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.

Unvented roof systems.

As a result unvented roofs have become popular in homes with feature dense roofs think multiple skylights dormers and other aesthetic flourishes. Many local building codes do not account for non standard construction alternatives such as unvented attic assemblies. Also unvented roof assembles make complicated roof geometries more viable as they are difficult to ventilate effectively. Removing moisture from roof cavities structural members sheathing and insulation.

Air permeable insulation such as fiberglass batts dense packed cellulose or blown in fiberglass can t be used alone for an unvented assembly since these types of insulation can allow moist indoor air to reach the cold roof sheathing leading to condensation or moisture accumulation. In cold climates insulating sheathing must be added exterior to the roof sheathing to prevent condensation on the underside of the roof sheathing. However designers of compact roof assemblies must consider vapor permeance and arrangement of the roofing materials to produce acceptable hygrothermal performance and low. 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. Enhancing roofing material life span by reducing sheathing temperature. An unvented roof assembly is constructed without any ventilation and is fully sealed on all sides and filled with insulation. Controlling ice damming by keeping the roof cold.

Ventilation becomes more difficult the more complicated a roof s construction is. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck. These roofs have some pros and cons as explained in the article. Unvented roof systems can be safely used in many different climates.

When properly installed unvented roofs perform well and cause no excess. There are traditionally four main reasons for venting a roof. Unvented roofs vented roof. A system most likely to be found in newly built homes.

Unvented roofs have a number of advantages.