Warm Deck Roof Ventilation

Ventilation for cold roofs.

Warm deck roof ventilation.

Ventilation for flat roofs warm roofs. If the attic space is going to be conditioned either for living or mechanical purposes or if a home design calls for a vaulted ceiling provision r806 3 in the international residential code calls for the roof deck above the space to be vented continuously from the eave to the ridge. Figure 6 flat roof cold deck both the warm deck and inverted warm deck construction will have insulation placed above the roof deck. They are meant to let the air from indoors travel outdoors so there is continuous air flow.

A cold roof is where all of the insulation is placed either between and under or completely under the joists. 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. For a simple duo pitch roof bs 5250 specifies sufficient ventilation as being. When thermal insulation is placed below the deck the ventilation must also be on the underside.

The trapped hot air goes out from the attics through the ventilation space into nature. A sealed warm roof construction can also be achieved by creating a 50mm ventilated air gap between the surface of the insulation and the undertile lining to allow water vapour to be safely removed from the roof construction. Warm roof ventilation specification. Vent the roof deck.

A warm roof is defined as being when the all or the majority of the insulation is above the joists or deck. There is no need for additional ventilation. There are three main types of flat roof construction namely cold deck warm deck and inverted warm deck the only one of which requires ventilation being the cold deck see figures 6 and 7. Exhaust vents unlike intake vents are installed at the topmost point of the roof.

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. Where the insulation is placed above the structural deck warm deck and either above or below the waterproofing. If ridge or eaves ventilation is not possible ventilation tiles can be used at high or low level to achieve the required airflow. In the instances where a warm flat roof has been laid ventilation isn t usually required.

There are two types of flat roof systems warm and cold roofs which affect the positioning of the ventilation. In pitched roof construction thermal insulation can be placed horizontally at ceiling level cold roof.