Unvented Roof Ontario

When we renovated our home we changed our addict being unvented.

Unvented roof ontario.

The most common way to eliminate venting from a roof assembly is to use a spray foam spf insulation. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. These roofs are code conforming except they do not display the venting requirements expressed in the building code. Next i ll be screwing down 5 1 2 raycore sips panels over heated space and framing.

With tribuilt granulated self adhering underlayment on top of the plywood. 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. An understanding of heat air and moisture as well as the causes of condensation is critical in detailing unvented roof assemblies.

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. We have 7 on the entire underside of the roof. We had closed cell foam sprayed on the underside of the roof. Beams on 5 centers.

Preventing moisture is essential for having a properly functioning un vented roof. Unvented roofs are more common in today s modern home designs. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck. According to the building code an unvented roof assembly needs r 20 of rigid foam above the roof sheathing for climate zone 5 or r 25 of rigid foam above the roof sheathing for for climate zone 6.

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. Nails shall have sufficient length to penetrate through or 12 mm into roof sheathing. Potential pitfalls to avoid include. 1 1 2 t g decking.

3 8 plywood diaphragm seams taped. 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. Unvented roofs are increasingly common due to design priorities. 1 nails nails used for roofing shall be corrosion resistant roofing or shingle nails conforming to csa b111 wire nails spikes and staples.

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. Hopefully a roofing contractor never makes a mistake with nails. 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.