Unvented Roof 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 roof ontario.

We have 7 on the entire underside of the roof. 1 1 2 t g decking. The most common way to eliminate venting from a roof assembly is to use a spray foam spf insulation. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck.

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. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. A combination of vented and unvented assemblies was studied including vented fibreglass. We had closed cell foam sprayed on the underside of the roof.

3 8 plywood diaphragm seams taped. 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. Unvented roofs are more common in today s modern home designs.

Preventing moisture is essential for having a properly functioning un vented roof. With tribuilt granulated self adhering underlayment on top of the plywood. 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. Potential pitfalls to avoid include.

The roof is currently built as follows. 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. 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. 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.

Unvented roofs are increasingly common due to design priorities. An understanding of heat air and moisture as well as the causes of condensation is critical in detailing unvented roof assemblies. Highlights of the ontario building code. Hi everyone need to make a final decision on which underlayment to use under a metal roof on an unvented roof system.

Beams on 5 centers. Hopefully a roofing contractor never makes a mistake with nails. When we renovated our home we changed our addict being unvented.