2/12 Roof Pitch

A 2/12 roof (also written 2:12 or "2 on 12") rises 2 inches for every 12 inches of horizontal run: 9.46°, a 16.7% slope, and 1.4% more surface than its footprint.

2/12 pitch at a glance
Measure	2/12 value
Angle	9.46°
Slope percent	16.7%
Rise per foot of run	2 in
Pitch multiplier (area factor)	1.0138
Hip/valley factor	1.4240
Common rafter length per foot of run	12-3/16"
Plumb cut / seat cut	9.5° / 80.5°

Where you see a 2/12 roof

Typical uses: porch roofs tucked under upstairs windows, additions and modern shed roofs. A 2/12 roof is the lowest pitch where the IRC allows asphalt shingles, and only with two layers of underlayment (or an approved equivalent such as a full ice-and-water membrane). Many roofers prefer metal or a membrane at this slope because wind-driven rain can work under shingles that sit almost flat.

Roof area at 2/12

2/12 formulas

Angle = arctan(2 ÷ 12) = 9.46° Multiplier = √(2² + 12²) ÷ 12 = 1.0138 Roof area = footprint × 1.0138 Rafter = run × 1.0138 Ridge height = run × 2 ÷ 12

Worked examples

Roof area. A 48 × 30 ft house with 1 ft overhangs has a 50 × 32 = 1,600 sq ft footprint. At 2/12: 1,600 × 1.0138 = 1,622 sq ft, or 16.2 squares before waste.

Rafter. A 28 ft span with a 1-1/2" ridge board has a 13.938 ft run. Line length = 13.938 × 1.0138 = 14' 1-9/16"; add an 18" overhang (1' 6-1/4" along the slope) for 15' 7-13/16". The ridge sits 2' 4" above the plate line. Try other spans in the rafter calculator.

2/12 rafter lengths and ridge heights

Common rafters at 2/12, measured to the center of the ridge
Building span	Run	Rafter (no overhang)	Ridge rise
16 ft	8 ft	8' 1-5/16"	1' 4"
20 ft	10 ft	10' 1-5/8"	1' 8"
24 ft	12 ft	12' 2"	2' 0"
28 ft	14 ft	14' 2-5/16"	2' 4"
32 ft	16 ft	16' 2-5/8"	2' 8"
36 ft	18 ft	18' 3"	3' 0"

Roof area by footprint at 2/12

Footprint to roof area at 2/12
Footprint (incl. overhang)	Roof area	Squares
1,000 sq ft	1,014 sq ft	10.1
1,500 sq ft	1,521 sq ft	15.2
2,000 sq ft	2,028 sq ft	20.3
2,500 sq ft	2,534 sq ft	25.3
3,000 sq ft	3,041 sq ft	30.4

Materials and walkability

Shingles: Yes, but codes require double underlayment (or an approved equivalent) between 2/12 and 4/12.
Walkable? Generally yes, in dry conditions with proper footwear and fall protection where required.
OSHA class: Low-slope (OSHA): OSHA treats anything steeper than 4/12 as a steep roof for fall-protection rules.

Roofing materials allowed on a 2/12 roof

Minimum pitch by roofing material vs a 2/12 roof (IRC R905)
Roof covering	Code minimum	OK at 2/12?
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, design slope for drainage
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, double underlayment from 2/12 up to 4/12
Clay and concrete tile	2.5/12 (IRC R905.3.2)	No
Metal roof shingles	3/12 (IRC R905.4.2)	No
Lapped metal panels, no sealant (exposed-fastener)	3/12 (IRC R905.10.2)	No
Wood shingles and shakes	3/12 (IRC R905.7, R905.8)	No
Slate	4/12 (IRC R905.6.2)	No

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.

← 1/12 pitch · 3/12 pitch → · All pitches in degrees

Frequently asked questions

How many degrees is a 2/12 roof pitch?

A 2/12 roof pitch is 9.46 degrees.

What is the multiplier for a 2/12 pitch?

The pitch multiplier for 2/12 is 1.0138. Multiply the footprint area or horizontal run by it to get the sloped area or rafter length.

Can you put shingles on a 2/12 roof?

Yes, but codes require double underlayment (or an approved equivalent) between 2/12 and 4/12.

Is a 2/12 roof walkable?

Generally yes, in dry conditions with proper footwear and fall protection where required.

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.