Warm Deck Roof Ventilation

Warm deck this is where the insulation is placed on top of the rafters joists and the roof covering is then placed over the insulation.

Warm deck roof ventilation.

25mm at eaves on each slope and 5mm at ridge. There are two ways to insulate a roof. The insulation is placed above the roof deck but below the weatherproof membrane. Construction studies drawing detail showing how to draw a flat roof warm deck construction detail to a scale of 1 10 with a short introduction highlighting t.

Building regulations state that a ventilation gap of at least 50mm must be in place between the insulation and the underside of the flat roof deck. By majority the rule of thumb is that in a domestic house not flats approximately a third of the total thermal performance of insulation can be placed below the deck with two thirds above the deck sometimes this is called a hybrid warm roof. Where difficulty is experienced in achieving effective cross ventilation a warm deck roof will be required. In mixed climates ventilation serves either role depending on the season.

Ventilation is required to the underside of the deck. If ridge or eaves ventilation is not possible ventilation tiles can be used at high or low level to achieve the required airflow. Ventilation is not needed in a warm roof. No ventilation is required for these types of roofs.

A cold roof design is generally not recommended for new build roof applications due to the added requirement for roof void ventilation and the difficulties in preventing. Adequate ventilation must be provided between the insulation and the underside of the roof deck to prevent the risk of interstitial condensation forming within the void area. In flat roof construction thermal insulation can be placed above and below the structural roof deck or waterproofing layer. In a hot climate the primary purpose of ventilation is to expel solar heated hot air from the attic or roof to reduce the building s cooling load and to relieve the strain on air conditioning systems.

Warm deck roof a warm deck roof is where the insulation is placed on top of the rafters joists and the roof covering is then placed over the insulation. Warm roof ventilation specification for a simple duo pitch roof bs 5250 specifies sufficient ventilation as being.