Ontario Roof Pitch

Roof framing suggestions canadian guidelines.

Ontario roof pitch.

Roof pitch is the measurement of a roof s vertical rise divided by its horizontal run. In the united states a run of 12 inches 1 foot is used and pitch is measured as the rise of the roof over 12 inches. Coal tar base gravelled 1 in 50 1 1 in 25. Greek says one must keep rafter length in range of 1 9 to 1 7 th of span but as per roman style the standard dimensions are kept about 1 3 to 2 9 th of span with an angle of 23 to 24 degree.

The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. This article excerpts from provides copies of roof framing suggestions from canadian building codes and the cmhc wood frame house construction guide. With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 200 for slate roofs. The table below shows common roof pitches and the equivalent grade degrees and radians for each.

For a gothic style the rafters must equal the span 60 while an elizabethan style requires the rafters to be longer than the span. I e 4 inches of rise per 12 inches one foot of run. A pitch over 9 12 is considered a steep slope roof between 2 12 and 4 12 is considered a low slope roof and less than 2 12 is considered a flat roof. If a roof slope rises say 4 inches when measured 12 inches along the bottom of a horizontal roof truss the roof slope is said to be 4 12.

You could also opt for a pvc flat roofing membrane. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. In snowy areas your roof should be at least 10 12 40 to allow snow to shed while the safest roof pitch in very windy areas is between 4 12 6 12 18 5 26 5. So you would need to pick the right option as most regular standing seam metal roofs will require a roof pitch of 2 12 or even 3 12 at a minimum.

Glass fibre reinforced polyester roofing panels. It is often compared to slope but is not exactly the same. For instance a 7 12 roof pitch means that the roof rises 7 inches. Modified bituminous membranes.

Asphalt base gravelled 1 in 50 1 1 in 4. Framing any roof but particularly a gable roof low slope roof and cathedral ceilign roofs requires collar ties rafter ties and possibly a structural ridge beam to support the roof and to. Usually average roof pitch is determined using the same roof length method. Asphalt base without gravel 1 in 25.