What a 22/12 pitch means
A 22/12 roof rises 22 inches for every 12 inches it runs horizontally, which is an angle of 61.39° from level and a 183.3% slope. It is a steep roof, too steep to walk safely without roof jacks or a harness.
Roofing for a 22/12 roof
Suits shingles, metal, slate and tile. Steep enough that roofers need roof jacks or harnesses, which adds to labour cost.
Rise and rafter length at 22/12
For a gable roof, the run is half the building width. Rafter lengths are before the ridge deduction and overhang.
| Run | Building width | Rise | Rafter length |
|---|---|---|---|
| 4 ft | 8 ft | 7' 4" | 8' 4 1/4" |
| 6 ft | 12 ft | 11' | 12' 6 3/8" |
| 8 ft | 16 ft | 14' 8" | 16' 8 1/2" |
| 10 ft | 20 ft | 18' 4" | 20' 10 5/8" |
| 12 ft | 24 ft | 22' | 25' 3/4" |
| 14 ft | 28 ft | 25' 8" | 29' 2 13/16" |
| 16 ft | 32 ft | 29' 4" | 33' 4 15/16" |
| 20 ft | 40 ft | 36' 8" | 41' 9 3/16" |
Roof area at 22/12
Multiply the building footprint (including the overhangs) by 2.088 to get the roof surface. A 30 × 40 ft footprint has 2506 sq ft of roof at 22/12 — about 79 sheets of 4 × 8 sheathing before waste.