10/12 roof pitch
A 10/12 roof rises 10 inches for every 12 inches it runs: an angle of 39.8°, and a very steep roof. You see it on Tudor and Victorian homes, A-frames and many cottage styles.
- Angle
- 39.81°
- Slope
- 83.3%
- Area multiplier
- ×1.302
- Rafter per foot of run
- 15.62"
What 10/12 means for your roof
Size. A roof is bigger than the ground it covers. At 10/12 every square foot of footprint carries 1.302 sq ft of roof, so a 2,000 sq ft house has about 2,603 sq ft (26.0 squares) of roofing before overhangs and waste. A quote measured on the footprint alone under-buys every shingle and every hour of labour by 30.2%.
Working on it. Not walkable: every square is laid from brackets or scaffolding with full fall protection. Expect a clear steep-roof premium in any quote. Federal safety rules (OSHA 1926.500) treat any roof above 4/12 as a steep roof.
Cost. Replacing architectural shingles on that 2,000 sq ft house, old layer torn off, comes to about $14,400–$16,500 at US-average roofer wages. That figure follows the roof's area only: the steep-roof labour charge most roofers add at this pitch comes on top. Price your own roof from satellite.
Roofing materials at 10/12
Minimum slopes in the International Residential Code (2021). Cities adopt it with changes, and a manufacturer's instructions can be stricter, so check locally before you buy.
- Asphalt shingles — allowed (minimum 2/12, IRC R905.2.2)
- Clay or concrete tile — allowed (minimum 2½/12, IRC R905.3.2)
- Metal shingles — allowed (minimum 3/12, IRC R905.4.2)
- Slate — allowed (minimum 4/12, IRC R905.6.2)
- Standing-seam metal panels — allowed (minimum ¼/12, IRC R905.10.2)
10/12 pitch questions
What is a 10/12 roof pitch in degrees?
39.81 degrees. The angle is arctan(10 ÷ 12). As a percent slope it is 83.3%.
How much bigger is a 10/12 roof than the house's footprint?
Multiply the footprint by 1.302. A 2,000 sq ft footprint has about 2,603 sq ft of roof at 10/12, before overhangs and waste.
Can you put shingles on a 10/12 roof?
Yes. 10/12 is within normal shingle installation; the model building code allows asphalt shingles from 2/12 up.
Is a 10/12 roof walkable?
Not walkable: every square is laid from brackets or scaffolding with full fall protection. Expect a clear steep-roof premium in any quote.
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