Attic Ventilation Requirements Canada

Of vent for every 300 sq.

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. Building codes vary. Most building codes require a ratio of 1 150 ventilation space to attic floor space. 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 ratio of vent area to ceiling area should be approximately 1 to 300. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. The ontario building code vent requirements 9 19 1 2.

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

However in more extreme environments including much of canada during winter it can be a problem. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. 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 following are the requirements taken directly from the irc.

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. You can also contact your local municipality to check on building code in your area. For minimum building code requirements use the 1 300 ratio instead of the 1 150 ratio. Although an airtight ceiling will significantly reduce the likelihood of moisture in the attic building codes still require minimum attic ventilation.

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