Eave Protection (Canada)

Eave protection is the term used in the National Building Code of Canada (NBC) and provincial codes based on it, such as the Ontario Building Code, for a membrane installed along the lower edge of a sloped roof to prevent leaks from ice dams and wind-driven water. It corresponds to the "ice barrier" of the US International Residential Code.

Extent

Under Part 9 Article 9.26.5.1, as reproduced from the Ontario Building Code, eave protection on shingle, shake or tile roofs must extend from the roof edge at least 900 mm (about 35 in) up the slope, and to a line not less than 300 mm (about 12 in) inside the inner face of the exterior wall. The inside-the-wall measurement is what usually controls on houses with wide overhangs.

Exceptions

The same reproduced text lists situations where eave protection is not required, including:

• roofs over unheated garages, carports and porches;
• roofs where the overhang, measured along the slope from the edge to the inner face of the exterior wall, exceeds 900 mm;
• roofs with a slope of 1 in 1.5 or steeper;
• regions with 3,500 or fewer degree-days;
• asphalt shingle roofs installed under the code's low-slope shingle provisions.

Provinces and municipalities can amend these rules, and code editions change, so the current adopted code should be checked.

Materials

Eave protection is commonly made from self-adhered modified-bitumen membranes, although the code also recognises other membrane types. Products are installed over the deck at the eaves, under the drip edge arrangement specified by the shingle manufacturer.

Related concepts

The comparable US requirement is the "ice barrier" of the International Residential Code. The underlying principle is the same: keep the lowest, coldest part of the roof watertight even when water is ponded behind ice.