How To Ventilate A Pitched Roof

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.

How to ventilate a pitched roof.

The code also allows for air permeable insulation such as fiberglass or cellulose to be used under the roof deck as long as rigid foam is used above the roof sheathing. For the best results place roof ventilation near the roof s peak and soffit vents in the eaves. It is important that air movement occurs and is not impeded by any framing members of the home. A ridge vent is a ventilation strip that is placed along the ridgeline of the home.

Damp in roof space as a general rule of thumb slated or tiled roofs without underslaters felt tend to breathe and ventilate through natural gaps in the slate. Prior to installing the ridge vent a 1 inch wide strip of roof decking is cut out along both sides of the ridgeline to allow for air movement through the vent. Vents come in various styles. Condensation control is most often accomplished by installing rigid foam above the roof deck or by installing air impermeable spray foam insulation directly against the underside of the roof deck.

We chose rectangular hooded roofing vents and rectangular soffit vents because they re easy to install. When we talk about roof ventilation we often focus on the cut itself. Air flows in through the soffit vents and out through the roof vents. The principle applied here is warm moist air rising from below is allowed to permeate through the roof membrane removing the need to fully ventilate the roof.

However there are many other critical steps that we need to master in order to make roof ventilation an efficient process. Bs 5250 sets out the minimum requirements for roof space ventilation.