Cold Flat Roof Construction Ventilation

Cold deck flat roof the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification.

Cold flat roof construction ventilation.

Ventilation for cold roofs. Cold roof voids are generally always required to be ventilated. The flat roof is finished in grp. A ventilation gap usually 50mm should be.

However where vapour permeable or low resistance lr underlays are specified the levels required may be reduced. The enclosed void of a warm pitched roof may not require to be ventilated but this is usually subject to the requirement to install a fully sealed air and vapour control layer avcl in conjunction with an air open roof covering. The ventilation system required for a cold flat roof must be installed during the construction of the roof itself. Hopefully this video will help explain the difference between cold flat roof construction and warm flat roof construction this videos show detailed drawings.

This video shows the key features of a flat roof cold deck construction and how to draw the details to a scale of 1 10. A cold roof really is colder than the rest of your home in the winter which means condensation is much less likely to develop. In a concrete deck for example this gap could be created by fixing 50x50mm timber battens at 600mm centres and attaching the insulation to underside of these battens. I have an outbuilding which has a cold flat roof construction.

However there is currently no ventilation and i am concerned that during the colder months warm air from the room below will rise up and meet with the colder air forming condensation and water droplets. That means the rest of the roof is protected from heat. Their layer of insulation is beneath the roof decking and the roofing membranes. This significantly reduces the amount of rising heat and in turn condensation.