2/12 roof pitch: 9.46 degrees
A 2/12 roof pitch is 9.4623° to four places. Its multiplier, or rafter factor, is 1.013794, its grade is 16.67% and its slope ratio is 1 : 6.
Change the pitch
9.4623°≈
Multiply your run by 1.013794 for the rafter length. Hips and valleys at this pitch are in the app.
Rafter length at 2/12, by span
Run is half the span on a symmetrical gable. Length is along the rafter, before any birdsmouth, ridge or tail is taken off.
| Building span | Run | Rafter length | Decimal feet |
|---|---|---|---|
| 20 ft | 10 ft | 10' 1-5/8" | 10.138 ft |
| 24 ft | 12 ft | 12' 2" | 12.166 ft |
| 28 ft | 14 ft | 14' 2-5/16" | 14.193 ft |
| 32 ft | 16 ft | 16' 2-5/8" | 16.221 ft |
| 36 ft | 18 ft | 18' 3" | 18.248 ft |
Every row is the run multiplied by 1.013794, the rafter factor for 2/12. The multiplier for every pitch is on the roof pitch multiplier table.
What 2/12 means on the roof
Two in twelve is the shallowest roof the IRC will allow asphalt shingles on at all, and then only with a doubled underlayment. Below it, shingles are off the table and the roof wants a membrane or standing seam instead.
The working is the arctangent of the rise over the run: atan(2 ÷ 12) = 9.4623°. The rafter factor is the hypotenuse of the same triangle over its base, √(12² + 2²) ÷ 12, which is why multiplying any run by 1.013794 gives the rafter. That figure is the roof pitch multiplier, and it is the same number whatever the size of the roof.
A hip or valley where both roofs are 2/12 runs at 45° across the plan, so it is longer than the common rafter beside it: 1.4240 ft of hip for every foot of common run, which is 14' 2-7/8" over a 10 ft common run against 10' 1-5/8" for the rafter.
Shingle slope limits quoted here are from the IRC, the United States model code. Your state, province or county may amend them, and several do.
Other pitches: 1/12 · 3/12 · 4/12 · 4.5/12 · 5/12 · 6/12 · 6.5/12 · 7/12 · 8/12 · 9/12 · 10/12 · 11/12 · 12/12. Every pitch from 1/12 to 24/12 is on the roof pitch to degrees chart.
