8/12 Roof Pitch
A 8/12 roof (also written 8:12 or "8 on 12") rises 8 inches for every 12 inches of horizontal run: 33.69°, a 66.7% slope, and 20.2% more surface than its footprint.
| Measure | 8/12 value |
|---|---|
| Angle | 33.69° |
| Slope percent | 66.7% |
| Rise per foot of run | 8 in |
| Pitch multiplier (area factor) | 1.2019 |
| Hip/valley factor | 1.5635 |
| Common rafter length per foot of run | 14-7/16" |
| Plumb cut / seat cut | 33.7° / 56.3° |
Where you see a 8/12 roof
Typical uses: two-story homes, cottages and homes in snow country. An 8/12 roof (33.7 degrees) reads as steep from the street. Snow slides off more readily, and attic space starts to become useful. Most roofers treat it as steep work, with roof jacks or a harness, which adds labor time.
Roof area at 8/12
8/12 formulas
Worked examples
8/12 rafter lengths and ridge heights
| Building span | Run | Rafter (no overhang) | Ridge rise |
|---|---|---|---|
| 16 ft | 8 ft | 9' 7-3/8" | 5' 4" |
| 20 ft | 10 ft | 12' 1/4" | 6' 8" |
| 24 ft | 12 ft | 14' 5-1/16" | 8' 0" |
| 28 ft | 14 ft | 16' 9-15/16" | 9' 4" |
| 32 ft | 16 ft | 19' 2-3/4" | 10' 8" |
| 36 ft | 18 ft | 21' 7-5/8" | 12' 0" |
Roof area by footprint at 8/12
| Footprint (incl. overhang) | Roof area | Squares |
|---|---|---|
| 1,000 sq ft | 1,202 sq ft | 12.0 |
| 1,500 sq ft | 1,803 sq ft | 18.0 |
| 2,000 sq ft | 2,404 sq ft | 24.0 |
| 2,500 sq ft | 3,005 sq ft | 30.0 |
| 3,000 sq ft | 3,606 sq ft | 36.1 |
Materials and walkability
- Shingles: Yes. 4/12 and steeper takes a standard shingle installation.
- Walkable? With care. Many roofers use toe boards or roof jacks at this pitch.
- OSHA class: Steep roof (OSHA): OSHA treats anything steeper than 4/12 as a steep roof for fall-protection rules.
Roofing materials allowed on a 8/12 roof
| Roof covering | Code minimum | OK at 8/12? |
|---|---|---|
| Standing-seam metal panels | 0.25/12 (IRC R905.10.2) | Yes |
| Built-up, modified bitumen, single-ply membrane (TPO, EPDM, PVC) | 0.25/12 (IRC R905.9, R905.11, R905.12) | Yes |
| Lapped metal panels with lap sealant | 0.5/12 (IRC R905.10.2) | Yes |
| Mineral-surfaced roll roofing | 1/12 (IRC R905.5.2) | Yes |
| Asphalt shingles | 2/12 (IRC R905.2.2) | Yes |
| Clay and concrete tile | 2.5/12 (IRC R905.3.2) | Yes |
| Metal roof shingles | 3/12 (IRC R905.4.2) | Yes |
| Lapped metal panels, no sealant (exposed-fastener) | 3/12 (IRC R905.10.2) | Yes |
| Wood shingles and shakes | 3/12 (IRC R905.7, R905.8) | Yes |
| Slate | 4/12 (IRC R905.6.2) | Yes |
Sources
- International Code Council, International Residential Code (2021 and 2024), Section R905 minimum slopes, as summarized in IRC 2024 Chapter 9 (UpCodes) and the MyBuildingPermit residential re-roof checklist. Local amendments and manufacturer instructions can be stricter.
- OSHA, 29 CFR 1926.500(b): a low-slope roof is 4 in 12 or less; a steep roof is greater than 4 in 12. 1926.501(b)(13) requires fall protection for residential construction work 6 ft or more above a lower level.
← 7/12 pitch · 9/12 pitch → · All pitches in degrees
Frequently asked questions
How many degrees is a 8/12 roof pitch?
A 8/12 roof pitch is 33.69 degrees.
What is the multiplier for a 8/12 pitch?
The pitch multiplier for 8/12 is 1.2019. Multiply the footprint area or horizontal run by it to get the sloped area or rafter length.
Can you put shingles on a 8/12 roof?
Yes. 4/12 and steeper takes a standard shingle installation.
Is a 8/12 roof walkable?
With care. Many roofers use toe boards or roof jacks at this pitch.
Last reviewed 2026-10-21. Results are estimates for planning; confirm quantities with your supplier and requirements with your local building code and the manufacturer's instructions.