Roof pitch reference
5/12 roof pitch
A 5/12 roof rises 5 inches per 12 inches of run: 22.6°, a 41.7% grade, slope factor 1.0833. Each foot of run is 13 inches along the slope.
√(1 + (5 ÷ 12)²) = 1.0833 · between 4/12 (+5.4%) and 6/12 (+11.8%).
Roof area at 5/12
| Footprint | Roof at 5/12 | Squares |
|---|---|---|
| 1,200 sq ft | 1,300 sq ft | 13 |
| 1,600 sq ft | 1,733 sq ft | 17.3 |
| 2,000 sq ft | 2,167 sq ft | 21.7 |
| 2,600 sq ft | 2,817 sq ft | 28.2 |
Rafter length at 5/12
| Run (half span) | Rafter, no overhang |
|---|---|
| 10 ft | 10 ft 10 in (10.83 ft) |
| 12 ft | 13 ft 0 in (13 ft) |
| 14 ft | 15 ft 2 in (15.17 ft) |
| 16 ft | 17 ft 4 in (17.33 ft) |
Ice barrier on a 5/12 roof in Ohio and Michigan
Freeze-thaw winters in both states make eave protection one of the most important details on a 5/12 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 22.6° slope that distance grows by 8.3% when measured up the roof:
| Overhang | Horizontal | Up the 5/12 slope | 36-in courses |
|---|---|---|---|
| 12 in | 36 in | 39 in | 2 |
| 18 in | 42 in | 45.5 in | 2 |
| 24 in | 48 in | 52 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 5/12
At 5/12 (22.6°, 41.7% grade) asphalt shingles install with standard underlayment under the IRC, plus ice barrier where the local code requires it.
Working on a 5/12 roof
Most crews can work a 22.6° roof with standard setups. At 5/12, 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 5/12 falls under steep-roof fall protection rules.
Frequently asked questions
What angle is a 5/12 roof?
A 5/12 roof is about 22.6° from horizontal, a 41.7% grade. Over a 10-foot run it rises 4.17 feet.
How much bigger is a 5/12 roof than the footprint?
The slope factor is 1.0833, so the roof is 8.3% larger than the flat area under it. A 1,600 sq ft footprint has about 1,733 sq ft of roof (17.3 squares).
Can you put asphalt shingles on a 5/12 roof?
At 5/12 (22.6°, 41.7% 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 5/12 roof need at the eaves?
With a 12-inch overhang, reaching 24 inches inside the wall takes about 39 inches measured up a 5/12 slope, which is 2 courses of 36-inch membrane with a 3-inch lap. Your local code decides whether ice barrier is required.