Roof pitch reference
7/12 roof pitch
A 7/12 roof rises 7 inches per 12 inches of run: 30.3°, a 58.3% grade, slope factor 1.1577. Each foot of run is 13.89 inches along the slope.
√(1 + (7 ÷ 12)²) = 1.1577 · between 6/12 (+11.8%) and 8/12 (+20.2%).
Roof area at 7/12
| Footprint | Roof at 7/12 | Squares |
|---|---|---|
| 1,200 sq ft | 1,389 sq ft | 13.9 |
| 1,600 sq ft | 1,852 sq ft | 18.5 |
| 2,000 sq ft | 2,315 sq ft | 23.2 |
| 2,600 sq ft | 3,010 sq ft | 30.1 |
Rafter length at 7/12
| Run (half span) | Rafter, no overhang |
|---|---|
| 10 ft | 11 ft 7 in (11.58 ft) |
| 12 ft | 13 ft 10.75 in (13.89 ft) |
| 14 ft | 16 ft 2.5 in (16.21 ft) |
| 16 ft | 18 ft 6.25 in (18.52 ft) |
Ice barrier on a 7/12 roof in Ohio and Michigan
Freeze-thaw winters in both states make eave protection one of the most important details on a 7/12 roof. Where the locally adopted code requires it, the model IRC (R905.1.2) extends ice barrier from the eave to at least 24 inches inside the exterior wall. On a 30.3° slope that distance grows by 15.8% when measured up the roof:
| Overhang | Horizontal | Up the 7/12 slope | 36-in courses |
|---|---|---|---|
| 12 in | 36 in | 41.7 in | 2 |
| 18 in | 42 in | 48.6 in | 2 |
| 24 in | 48 in | 55.6 in | 2 |
Courses assume a 3-inch lap (33 inches of coverage per 36-inch roll). Wall thickness adds a few inches. Check the product and your building department.
Shingles at 7/12
At 7/12 (30.3°, 58.3% grade) asphalt shingles install with standard underlayment under the IRC, plus ice barrier where the local code requires it.
Working on a 7/12 roof
Most crews can work a 30.3° roof with standard setups. At 7/12, snow usually sheds after a few sunny days, but eaves over unheated overhangs still ice up in freeze-thaw weather. OSHA treats anything steeper than 4/12 as a steep roof, so 7/12 falls under steep-roof fall protection rules.
Frequently asked questions
What angle is a 7/12 roof?
A 7/12 roof is about 30.3° from horizontal, a 58.3% grade. Over a 10-foot run it rises 5.83 feet.
How much bigger is a 7/12 roof than the footprint?
The slope factor is 1.1577, so the roof is 15.8% larger than the flat area under it. A 1,600 sq ft footprint has about 1,852 sq ft of roof (18.5 squares).
Can you put asphalt shingles on a 7/12 roof?
At 7/12 (30.3°, 58.3% grade) asphalt shingles install with standard underlayment under the IRC, plus ice barrier where the local code requires it.
How much ice barrier does a 7/12 roof need at the eaves?
With a 12-inch overhang, reaching 24 inches inside the wall takes about 41.7 inches measured up a 7/12 slope, which is 2 courses of 36-inch membrane with a 3-inch lap. Your local code decides whether ice barrier is required.