Roof pitch

11/12 roof pitch

A 11/12 roof rises 11 inches for every 12 inches it runs: an angle of 42.5°, and a very steep roof. You see it on gothic-revival and Victorian roofs, towers and steep gables.

run 12rise 11
Drawn to true scale: the angle on screen is the real angle.
Angle
42.51°
Slope
91.7%
Area multiplier
×1.357
Rafter per foot of run
16.28"

What 11/12 means for your roof

Size. A roof is bigger than the ground it covers. At 11/12 every square foot of footprint carries 1.357 sq ft of roof, so a 2,000 sq ft house has about 2,713 sq ft (27.1 squares) of roofing before overhangs and waste. A quote measured on the footprint alone under-buys every shingle and every hour of labour by 35.7%.

Working on it. Specialist work with scaffolding or ladders on brackets throughout. Fewer roofers bid it, which also lifts prices. 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 $15,000–$17,300 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 11/12

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)

Compare with the pitches either side

Other pitches: 2/12 · 3/12 · 4/12 · 5/12 · 6/12 · 7/12 · 8/12 · 9/12 · 10/12 · 12/12. Any other pitch, in degrees and to scale: roof pitch visualizer.

11/12 pitch questions

What is a 11/12 roof pitch in degrees?

42.51 degrees. The angle is arctan(11 ÷ 12). As a percent slope it is 91.7%.

How much bigger is a 11/12 roof than the house's footprint?

Multiply the footprint by 1.357. A 2,000 sq ft footprint has about 2,713 sq ft of roof at 11/12, before overhangs and waste.

Can you put shingles on a 11/12 roof?

Yes. 11/12 is within normal shingle installation; the model building code allows asphalt shingles from 2/12 up.

Is a 11/12 roof walkable?

Specialist work with scaffolding or ladders on brackets throughout. Fewer roofers bid it, which also lifts prices.

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