What a 6/12 pitch means
A 6/12 roof rises 6 inches for every 12 inches it runs horizontally, which is an angle of 26.57° from level and a 50% slope. It is a conventional roof, walkable without roof jacks.
Roofing for a 6/12 roof
Suits almost every roofing: asphalt shingles, metal, wood shakes, clay or concrete tile.
Rise and rafter length at 6/12
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 | 2' | 4' 5 11/16" |
| 6 ft | 12 ft | 3' | 6' 8 1/2" |
| 8 ft | 16 ft | 4' | 8' 11 5/16" |
| 10 ft | 20 ft | 5' | 11' 2 3/16" |
| 12 ft | 24 ft | 6' | 13' 5" |
| 14 ft | 28 ft | 7' | 15' 7 13/16" |
| 16 ft | 32 ft | 8' | 17' 10 11/16" |
| 20 ft | 40 ft | 10' | 22' 4 5/16" |
Roof area at 6/12
Multiply the building footprint (including the overhangs) by 1.118 to get the roof surface. A 30 × 40 ft footprint has 1342 sq ft of roof at 6/12 — about 42 sheets of 4 × 8 sheathing before waste.