18/12 roof pitch
56.31° angle
A 18/12 roof rises 18 in for every 12 in of run: a 150% slope with a 1.803 area multiplier.
| Pitch | 18 in 12 (18:12) |
|---|---|
| Angle | 56.31° |
| Slope | 150% |
| Roof area multiplier | 1.8028 |
| Rafter length per foot of run | 21.63 in |
| Type | A very steep roof |
Roofing for a 18/12 pitch
Suitable for asphalt shingles, metal, tile and most other roofing with standard underlayment. Not walkable: roofers work from roof jacks and fall protection, which adds labor cost.
Rafter length at 18/12
| Run (half the span) | Rise | Rafter length (before overhang) |
|---|---|---|
| 10 ft | 15 ft | 18.03 ft |
| 12 ft | 18 ft | 21.63 ft |
| 14 ft | 21 ft | 25.24 ft |
| 16 ft | 24 ft | 28.84 ft |
Change the numbers
Other roof pitches
Questions
- What angle is a 18/12 roof pitch?
- 56.31 degrees.
- What is a 18/12 roof pitch as a percentage?
- 150%: the roof rises 18 inches for every 12 inches of run.
- What is the roof multiplier for a 18/12 pitch?
- 1.803. Multiply the roof’s flat footprint by 1.803 to get its actual surface area.
- Is a 18/12 roof walkable?
- Not walkable: roofers work from roof jacks and fall protection, which adds labor cost.