Attic Ventilation Requirements Canada

Air vent recommends 1 square foot of ventilation for every 150 square feet of attic floor space with half the ventilation represented by intake vents and half by exhaust vents such as ridge vents.

Attic ventilation requirements canada.

The ontario building code vent requirements 9 19 1 2. The following are the requirements taken directly from the irc. Do not automatically increase ventilation. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.

Although an airtight ceiling will significantly reduce the likelihood of moisture in the attic building codes still require minimum attic ventilation. 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. However in more extreme environments including much of canada during winter it can be a problem. 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.

For minimum building code requirements use the 1 300 ratio instead of the 1 150 ratio. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Building codes vary. 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.

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 ratio of vent area to ceiling area should be approximately 1 to 300. The majority of the requirements related to attic ventilation have not changed much from the previous editions. 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.

In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. 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. 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. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.

These types of roofs therefore require more ventilation than common attic type roofs.