Roof Insulation Ventilation Gap

Where a warm roof is required it is usually possible to install all the insulation required within the depth of the rafters while leaving a clear ventilation gap of at least 50mm below their upper edge.

Roof insulation ventilation gap.

Use hardware cloth metal flashing or scrap plywood to create a safety gap of at least 3 inches all around fixtures. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves. Duo pitch roofs greater than 200 pitch or greater than 10m span should have additional ventilation at the ridge to assist airflow through the roof void equivalent to at least a 3 mm wide continuous gap. Staple a continuous polyethylene air and vapour barrier to the rafters and end wall studs.

However for rafters of less than 200mm dormer roofs for example it may be necessary to fix insulation boards to the lower face of the rafters. Seal any roof vents into the parts of the attic that are not heated. Roofing shingles and materials plus factory certified roofers including ratings from real homeowners from north america s largest roofing manufacturer. If the roof covering or roof membrane is a material of high moisture resistance or impermeable then the building regulations require a 50mm wide ventilation gap beneath the roofing felt and tiles.

This is typical practice when an old fashioned black sarking felt is in place and commonly found in existing buildings. Static vents often protrude from roofline thanks to. The code calls for a minimum of 1 in. Leave a clear space between the top of the insulation and the underside of the roof sheathing to allow for roof ventilation.

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. Then carefully seal the edges and seams with acoustical sealant. 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. Residential and commercial roofing shingles slate roof ventilation roof underlayments asphaltic and tpo roof membranes.

Direct all exhaust fans and vents to the exterior. Of airspace between the top of the insulation and the back of the roof sheathing. If you choose to vent the roof deck then be serious about it and really vent it. Installation of this type of attic ventilation involves leaving a gap in the sheathing along the ridge and covering it with a perforated vent.