Unventilated Roof Construction

Cold roof decks and external cladding or tiling.

Unventilated roof construction.

Poorly insulated ducting can cause heat loss in colder months and the loss of conditioned air in the summer in vented attics. Eliminating traditional ventilation and the potential condensation risk associated with large voids of cool air make this the optimum pitched roof solution. Eliminates large cool voids within the construction reducing thermal stress. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck.

Moisture content in roof structure must be less than 18 prior to covering. Unventilated attics are common where roof assemblies are complex and it s difficult to create a sealed ceiling plane. Together with not having to provide a ventilation pathway the technique permits insulation to be installed within the full depth of the rafter. Control construction moisture content with tenting or temporary roofing when necessary.

The ever increasing levels of thermal insulation required by thermal regulations can result in a higher risk of condensation forming on those elements not enclosed by this insulation e g. Breather membrane in colours. For designers the advantage of using unventilated construction comes from removing the necessity to provide a ventilated cavity below the sarking.