4/12 roof pitch
A 4/12 roof rises 4 inches for every 12 inches it runs: an angle of 18.4°, and a conventional roof. You see it on ranch and split-level homes, and most of the newer single-storey houses in the South and West.
- Angle
- 18.43°
- Slope
- 33.3%
- Area multiplier
- ×1.054
- Rafter per foot of run
- 12.65"
What 4/12 means for your roof
Size. A roof is bigger than the ground it covers. At 4/12 every square foot of footprint carries 1.054 sq ft of roof, so a 2,000 sq ft house has about 2,108 sq ft (21.1 squares) of roofing before overhangs and waste. A quote measured on the footprint alone under-buys every shingle and every hour of labour by 5.4%.
Working on it. Walkable for most roofers without extra fall gear, which keeps labour low. It is the lowest pitch where standard shingle installation applies, so it is a common, economical choice.
Cost. Replacing architectural shingles on that 2,000 sq ft house, old layer torn off, comes to about $11,700–$13,500 at US-average roofer wages. That figure follows the roof's area only: most roofers price standard labour at this pitch, with no steep-roof charge. Price your own roof from satellite.
Roofing materials at 4/12
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)
4/12 pitch questions
What is a 4/12 roof pitch in degrees?
18.43 degrees. The angle is arctan(4 ÷ 12). As a percent slope it is 33.3%.
How much bigger is a 4/12 roof than the house's footprint?
Multiply the footprint by 1.054. A 2,000 sq ft footprint has about 2,108 sq ft of roof at 4/12, before overhangs and waste.
Can you put shingles on a 4/12 roof?
Yes. 4/12 is within normal shingle installation; the model building code allows asphalt shingles from 2/12 up.
Is a 4/12 roof walkable?
Walkable for most roofers without extra fall gear, which keeps labour low. It is the lowest pitch where standard shingle installation applies, so it is a common, economical choice.
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