Unvented Roof Ontario

3 8 plywood diaphragm seams taped.

Unvented roof ontario.

Hi everyone need to make a final decision on which underlayment to use under a metal roof on an unvented roof system. Nails shall have sufficient length to penetrate through or 12 mm into roof sheathing. An understanding of heat air and moisture as well as the causes of condensation is critical in detailing unvented roof assemblies. The most common way to eliminate venting from a roof assembly is to use a spray foam spf insulation.

We had closed cell foam sprayed on the underside of the roof. Unvented roofs are more common in today s modern home designs. When we renovated our home we changed our addict being unvented. The primary concern with the use of unvented cathedralized attics is the potential for moisture build up at the underside of the roof sheathing during cold weather.

Once you have r 20 or r 25 of rigid foam on top of your sheathing you can safely insulate below your sheathing with almost any kind of. Next i ll be screwing down 5 1 2 raycore sips panels over heated space and framing. 1 nails nails used for roofing shall be corrosion resistant roofing or shingle nails conforming to csa b111 wire nails spikes and staples. Beams on 5 centers.

Preventing moisture is essential for having a properly functioning un vented roof. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. With tribuilt granulated self adhering underlayment on top of the plywood. Hopefully a roofing contractor never makes a mistake with nails.

For more than one year the university of waterloo s building enclosure group beg studied both open and closed cell foams in field in a test hut environment in southwestern ontario. Research has shown that the good field experience with ventilated attics is due to the removal of moisture that passes through the ceiling plane by diffusion and accidental air leaks during cold weather. Unvented roofs are increasingly common due to design priorities. 1 1 2 t g decking.

These roofs are code conforming except they do not display the venting requirements expressed in the building code. In an un vented roof foam can serve as the air barrier and vapor retarder and prevent moisture from getting in to the roof cavities. Potential pitfalls to avoid include. The roof is currently built as follows.

A combination of vented and unvented assemblies was studied including vented fibreglass. We didn t open up the 1st and 2nd floor walls but did going to the basement and spray the rim joists and any other open available areas. Highlights of the ontario building code.