How To Ventilate A Cold Flat Roof

I have a cold flat roof ventilated by soffit vents on one side and no ventilation on the other side.

How to ventilate a cold flat roof.

The requirements for a cold flat roof is to provide the equivalent of 25 000mm m of ventilation on two opposing sides of the roof in accordance with british standards bs5250 2011 control of condensation in buildings. 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. Ventilation for cold roofs. Your two best options are spray foam insulation on the underside of the roof sheathing an installation which will require the ceiling to be removed at least partially or the installation of rigid foam on top of the existing sheathing.

On the unventilated side there is no overhang just a solid facia board flush with the wall. Their layer of insulation is beneath the roof decking and the roofing membranes. A cold roof really is colder than the rest of your home in the winter which means condensation is much less likely to develop. How do i add ventilation on this side to create through air movement.

The glidevale technical team has co. Ventilating a flat roof on a warm flat roof the layer is installed underneath the insulation to stop moisture interacting with it through. 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. 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.

Why don t cold roofs need to be ventilated.