Attic Ventilation Requirements Canada

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.

Attic ventilation requirements canada.

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. 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. The majority of the requirements related to attic ventilation have not changed much from the previous editions.

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. Do not automatically increase ventilation. 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. You can also contact your local municipality to check on building code in your area.

The following are the requirements taken directly from the irc. Of vent for every 300 sq. The ratio of vent area to ceiling area should be approximately 1 to 300. 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. 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. 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.

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. These types of roofs therefore require more ventilation than common attic type roofs. For minimum building code requirements use the 1 300 ratio instead of the 1 150 ratio. 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.

Building codes vary.