Cold Roof Ventilation Gap

Cold deck roof a cold deck roof is where the insulation is placed between the joists rafters or in between the ceiling joists in the case of a pitch roof.

Cold roof ventilation gap.

Ventilation at the eaves. A cold roof is where all of the insulation is placed either between and under or completely under the joists or deck. See the benefits of attic ventilation a new roof is more than just shingles. Roof voids must be ventilated in order to stop warm air condensing on cold surfaces.

For both a warm and cold flat roof a vapour control layer must be installed. In a cold climate the primary purpose of ventilation is to maintain a cold roof temperature to avoid ice dams created by melting snow and to vent any moisture that moves from the conditioned. Ventilation is required for these roofs. Intake vents located at the lowest part of the roof under the eaves allow cool.

Continuous ventilation openings are made at the top and bottom. In this way the roof itself is kept cold. Introduction warm cold roofs this guidance offers guidance on the difference benefits between warm and cold roofs. Large cold pitched roof voids can be used to locate services such as water storage tanks associated pipes ventilation ducts electrical cables and recessed light fittings.

Condensation encourages rot and mould growth. Effective attic ventilation systems reduce damaging heat and moisture in your attic promote energy efficiency by helping to reduce the load on your air conditioner in the summer and also reduce the risk of ice dam formation on your roof. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves. In order to keep the integrity of the roof it is recommended to install vmzinc breather membrane on the cold side of the insulation and a vapour control layer adapted to the internal humidity load of the building on the warm side of the insulation.

Ventilation is not needed in a warm roof. No insulation is on top. 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. You only need ventilation in a cold roof.