Minimum Slope For Flat Roof Ontario

The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.

Minimum slope for flat roof ontario.

2 asphalt and gravel or coal tar and gravel roofs may be constructed with lower slopes than required in sentence 1 when effective drainage is provided by roof drains located at the lowest points on the roofs. Notes to table 9 26 3 1. The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles. A 2 slope is considered adequate in most instances with roof drainage either via eaves scuppers or drainage outlets in the roof itself.

In order to achieve this drop a slightly steeper angle of 1 40 1 44 should be the aim when installing a flat roof as this accounts for surface. Flat roof slope minimum according to the international building code the typical built up flat roof that uses tar or asphalt goes by the guideline that for every foot 12 inches of a flat roof a minimum of inch must step up or down. Normally 1 80 0 72 is the recommended minimum angle for a slope and this is universal across the vast majority of flat roofing systems regardless of the materials that they incorporate. The life expectancy on a correctly installed properly maintained flat roof is 20 to 25 years.

For metal panel roof systems with nonsoldered seams with applied lap sealant ibc 2018 prescribes a 1 2 12 minimum roof slope. Asphalt shingles continue to be the most widely installed roof covering option in north america. As the single ply roofing association spra points out this type of flat roofing is strong durable completely sealed and usually lasts at least 25 30 years. As opposed to old built up felt roofing with joins new single ply waterproof membranes are now most commonly used.

Nevertheless an engineered drainage plan is vital. Lapped nonsoldered seam metal roofs with applied lap sealant must have a minimum roof slope of 1 2 12 4 slope. It takes the manufacturer s recommendations the unique conditions of the roof as well as the skills and the expertise of the installer to arrive at the right slope. This is the basis for calculating the angle which is approximately a 1 19 degree slope.

Cold roofs and warm roofs. For standing seam metal roof panel systems a 1 4 12 minimum roof slope is prescribed. 2 see sentence 9 26 3 1 3. This 1 4 12 minimum roof slope requirement also applies to spray polyurethane foam spf roof systems in new construction.

3 profiled metal roof cladding systems specifically designed for low slope applications are. The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems. They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends. Lapped nonsoldered seam metal roofs without applied lap sealant must have a minimum roof slope of 3 12 25 slope.

In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory.