Cold Flat Roof Construction Ventilation

2011 code of practice for control of condensation in buildings stipulates that there should be a ventilation gap between the insulation and the bottom of the flat roof deck of at least 50mm.

Cold flat roof construction ventilation.

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. In many cases cold roofs are used in storage spaces where there is no habitation occurring underneath. A cold roof really is colder than the rest of your home in the winter which means condensation is much less likely to develop. 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.

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. This significantly reduces the amount of rising heat and in turn condensation. Ventilation for cold roofs. The flat roof is finished in grp.

I have an outbuilding which has a cold flat roof construction. Their layer of insulation is beneath the roof decking and the roofing membranes. Cold deck flat roof the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification. Hopefully this video will help explain the difference between cold flat roof construction and warm flat roof construction this videos show detailed drawings.

The ventilation system required for a cold flat roof must be installed during the construction of the roof itself. However where vapour permeable or low resistance lr underlays are specified the levels required may be reduced. That means the rest of the roof is protected from heat. A ventilation gap usually 50mm should be.