Attic Ventilation Requirements Canada

In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq.

Attic ventilation requirements canada. Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. Although an airtight ceiling will significantly reduce the likelihood of moisture in the attic building codes still require minimum attic ventilation. The ontario building code vent requirements 9 19 1 2. Of vent for every 300 sq.

Where the roof space is fairly larger for example cold uninhabited attic spaces with roof slopes of greater than 1 6 the total net vent area should be at least 1 300th of the area of insulated ceiling. The following are the requirements taken directly from the irc. For example depending on roof colour and orientation to the sun attic air temperatures can exceed 55 c 131 f when it is less than 38 c 100 f outside. The minimum is one square foot for every 300 square feet of attic floor space if there is a vapor retarder or the space is balanced between the ridge and intake vents.

Vent requirements 1 except as provided in sentence 2 the unobstructed vent area shall be not less than 1 300 of the insulated ceiling area. The majority of the requirements related to attic ventilation have not changed much from the previous editions. Building codes vary. However in more extreme environments including much of canada during winter it can be a problem.

2 where the roof slope is less than 1 in 6 or in roofs that are constructed with roof joists the unobstructed vent area shall be not less than 1 150 of the insulated ceiling area. Do not automatically increase ventilation. Generally they require ventilation rates of about 5 to 10 l s of outdoor air for each house occupant or roughly a complete house air change every three hours but these rates vary according to the number of occupants house volume occupant activities and the presence of indoor sources of pollutants. Vent requirements according to the ontario building codes you need one square foot of vent area for each 150 square feet of attic floor space.

The following product options will allow you to achieve an intake nfva of 528 square inches. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. The ratio of vent area to ceiling area should be approximately 1 to 300.