The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.
Minimum roof pitch in michigan.
Where the roof sheathing is less than 3 4 inch 19 1 mm thick the nails.
The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
The 2 12 number is rise over run or two units of vertical for every 12 units horizontal.
Importance of a roof pitch.
However you can only use this pitch with built up roofing or specialized synthetic roofing.
The chief reason for having a roof pitch is to redirect water and snow away from the roof and avoid any percolation that might result from stagnation of water on the roof.
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.
Roof slope multipliers for roof components of sloping roofs multiply by the figures given below to obtain the cost per square foot of horizontal projection.
Fasteners for asphalt shingles shall be galvanized stainless steel aluminum or copper roofing nails minimum 12 gage 0 105 inch 2 67 mm shank with a minimum 3 8 inch diameter 9 5 mm head of a length to penetrate through the roofing materials and a minimum of 3 4 inch 19 1 mm into the roof sheathing.
In general determining the pitch of an existing roof is a simple calculation.
Fasteners for asphalt shingles shall be galvanized steel stainless steel aluminum or copper roofing nails minimum 12 gage 0 105 inch 3 mm shank with a minimum 3 8 inch diameter 9 5 mm head complying with astm f1667 of a length to penetrate through the roofing materials and not less than 3 4 inch 19 1 mm into the roof sheathing.
You could also opt for a pvc flat roofing membrane.
There are some standing seam metal roofing options available from atas and other manufacturers that can be installed on a roof with pitch of 1 12.
Rise multiplier rise multiplier 1 to 12 1 01 6 to 12 1 12 2 to 12 1 01 8 to 12 1 20 3 to 12 1 03 12 to 12 1 42 4 to 12 1 06 15 to 12 1 60 5 to 12 1 08 18 to 12 1 80.
Shingles of all types need to have a slope to function properly.
They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends.
That works out to about nine degrees if that works better for you.
The minimum requirement is 2 12.
This can be accomplished by measuring the number of inches the roof rises vertically for every 12 inches it extends horizontally.
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.
What is the minimum pitch slope of an asphalt shingle roof.
