Cold Deck Flat Roof Ventilation

Ventilation is not needed in a warm roof.

Cold deck flat roof ventilation. 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. Introduction warm cold roofs this guidance offers guidance on the difference benefits between warm and cold roofs. You only need ventilation in a cold roof. No insulation is on top.

Ventilation is required for these roofs. For spans over 5m the gap should be increased to. Flat roof ventilation allows for the circulation of air in the property particularly for warmer rooms in residential buildings. Do have a minimum roof void of 50mm between the top of the insulation and the underside of the deck.

Guidance advice on warm cold. Ventilation is required to the underside of the deck. In this way the roof itself is kept cold. There are two types of flat roof systems warm and cold roofs which affect the positioning of the ventilation.

A cold roof is the most common type of roof construction often taking the form of an uninhabited storage space. There must be an adequate void minimum 50mm between the deck and the insulation traditionally mineral wool to allow free movement of air and to prevent moisture vapour being transmitted from the building outwards where it could condensate in the roof. In a cold roof construction the sarnafil membrane is installed directly to the structural decking usually timber with firrings to fall. For spans over 5m the roof void should be increased to 60mm.

Cold deck roofs do s and don ts. What is flat roof ventilation. Ventilate the roof void on two opposing sides with a minimum 25mm continuous ventilation strip. When thermal insulation is placed below the deck the ventilation must.

The minimum requirements for cold roof ventilation are set out in bs 5250 control of condensation in buildings which takes into consideration span pitch and roof area.