Guide
Shed roof pitch: chart, degrees and the minimum for each roof
A shed roof needs at least 2/12 (9.5°) for asphalt shingles, with two layers of underlayment up to 4/12, and 3/12 (14°) for screw-down metal panels, by the International Residential Code's minimum slopes. Our gable plans default to 6/12 (26.6°), and our lean-tos to 3/12, or 2/12 when they are deeper than 8 feet.
Steeper roofs shed water faster and give more headroom, but they make the shed taller and use more roofing. Below: pitch in degrees, the minimum for each roofing, and what pitch does to height, rafters and cost, worked out by our plans engine.
- 4/12
- 18.4°
- 6/12
- 26.6°
- 8/12
- 33.7°
- Shingles
- 2/12 minimum, double underlayment below 4/12
- Exposed-fastener metal
- 3/12 minimum
Roof pitch chart: pitch to degrees and percent
Pitch is written as the rise for a 12-inch run: a 6/12 roof climbs 6 inches for every foot it runs level. The angle is the arctangent of rise over run, and the rafter is longer than the run by the length factor (the hypotenuse of the triangle).
| Pitch | Angle | Slope | Rafter per foot of run | Rise over 5 ft (10 ft gable) | Rise over 8 ft (8 ft lean-to) |
|---|---|---|---|---|---|
| 1/12 | 4.8° | 8% | 1.003 ft | 5" | 8" |
| 2/12 | 9.5° | 17% | 1.014 ft | 10" | 1' 4" |
| 3/12 | 14° | 25% | 1.031 ft | 1' 3" | 2' 0" |
| 4/12 | 18.4° | 33% | 1.054 ft | 1' 8" | 2' 8" |
| 5/12 | 22.6° | 42% | 1.083 ft | 2' 1" | 3' 4" |
| 6/12 | 26.6° | 50% | 1.118 ft | 2' 6" | 4' 0" |
| 7/12 | 30.3° | 58% | 1.158 ft | 2' 11" | 4' 8" |
| 8/12 | 33.7° | 67% | 1.202 ft | 3' 4" | 5' 4" |
| 9/12 | 36.9° | 75% | 1.250 ft | 3' 9" | 6' 0" |
| 10/12 | 39.8° | 83% | 1.302 ft | 4' 2" | 6' 8" |
| 12/12 | 45° | 100% | 1.414 ft | 5' 0" | 8' 0" |
On a gable shed the run is half the width, so a 10-foot-wide shed at 6/12 rises 2' 6" from wall to ridge. A lean-to runs the whole depth in one slope.
The lowest pitch for each kind of roofing
The model residential code sets these minimums; your roofing's own instructions can ask for more, and its warranty may depend on it.
| Roofing | Minimum pitch | Section |
|---|---|---|
| Asphalt shingles | 2/12, with two layers of underlayment from 2/12 up to 4/12 | R905.2.2 |
| Lapped metal panels, exposed fasteners, no lap sealant | 3/12 | R905.10.2 |
| Lapped metal panels with lap sealant | 1/2 in 12 | R905.10.2 |
| Standing-seam metal | 1/4 in 12 | R905.10.2 |
| Metal roof shingles | 3/12 | R905.4.2 |
| Mineral-surfaced roll roofing | 1/12 | R905.5.2 |
| Wood shingles and shakes | 3/12 | R905.7.2, R905.8.2 |
| Clay and concrete tile | 2-1/2 in 12 | R905.3.2 |
Our plans follow the same lines: shingles from 2/12 with two layers of felt below 4/12, metal panels from 3/12, and gable roofs from 3/12 (anything flatter is a lean-to in our plans).
Pitch, rafters and height for 26 shed sizes
The rafter length is long point to long point, what you mark on the board, including the overhang. On the 10x12 gable at 6/12 the rafters are 2x6s cut to 6' 3-11/16".
| Shed | Pitch | Angle | Rafters | Rafter length | Height |
|---|---|---|---|---|---|
| 8x8 gable | 6/12 | 26.6° | 2x6 @ 16" | 5' 2-5/16" | 11' 5-15/16" |
| 8x10 gable | 6/12 | 26.6° | 2x6 @ 16" | 5' 2-5/16" | 11' 5-15/16" |
| 8x12 gable | 6/12 | 26.6° | 2x6 @ 16" | 5' 2-5/16" | 11' 5-15/16" |
| 10x10 gable | 6/12 | 26.6° | 2x6 @ 16" | 6' 3-11/16" | 11' 11-15/16" |
| 10x12 gable | 6/12 | 26.6° | 2x6 @ 16" | 6' 3-11/16" | 11' 11-15/16" |
| 10x14 gable | 6/12 | 26.6° | 2x6 @ 16" | 6' 3-11/16" | 11' 11-15/16" |
| 10x16 gable | 6/12 | 26.6° | 2x6 @ 16" | 6' 3-11/16" | 11' 11-15/16" |
| 12x12 gable | 6/12 | 26.6° | 2x6 @ 16" | 7' 5-1/8" | 12' 5-15/16" |
| 8x16 gable | 6/12 | 26.6° | 2x6 @ 16" | 5' 2-5/16" | 11' 5-15/16" |
| 12x14 gable | 6/12 | 26.6° | 2x6 @ 16" | 7' 5-1/8" | 12' 5-15/16" |
| 12x16 gable | 6/12 | 26.6° | 2x6 @ 16" | 7' 5-1/8" | 12' 5-15/16" |
| 12x18 gable | 6/12 | 26.6° | 2x6 @ 16" | 7' 5-1/8" | 12' 5-15/16" |
| 10x20 gable | 6/12 | 26.6° | 2x6 @ 16" | 6' 3-11/16" | 11' 11-15/16" |
| 12x20 gable | 6/12 | 26.6° | 2x6 @ 16" | 7' 5-1/8" | 12' 5-15/16" |
| 14x16 gable | 6/12 | 26.6° | 2x6 @ 16" | 8' 6-9/16" | 12' 11-15/16" |
| 16x16 gable | 6/12 | 26.6° | 2x6 @ 16" | 9' 7-15/16" | 13' 5-15/16" |
| 16x20 gable | 6/12 | 26.6° | 2x6 @ 16" | 9' 7-15/16" | 13' 5-15/16" |
| 4x8 lean-to | 3/12 | 14° | 2x6 @ 16" | 5' 3-1/4" | 10' 8-1/4" |
| 6x8 lean-to | 3/12 | 14° | 2x6 @ 16" | 7' 3-15/16" | 11' 2-1/4" |
| 8x8 lean-to | 3/12 | 14° | 2x6 @ 16" | 9' 4-11/16" | 11' 8-1/4" |
| 8x10 lean-to | 3/12 | 14° | 2x6 @ 16" | 9' 4-11/16" | 11' 8-1/4" |
| 8x12 lean-to | 3/12 | 14° | 2x6 @ 16" | 9' 4-11/16" | 11' 8-1/4" |
| 10x10 lean-to | 2/12 | 9.5° | 2x6 @ 16" | 11' 2-3/4" | 11' 3-7/8" |
| 10x12 lean-to | 2/12 | 9.5° | 2x6 @ 16" | 11' 2-3/4" | 11' 3-7/8" |
| 10x14 lean-to | 2/12 | 9.5° | 2x6 @ 16" | 11' 2-3/4" | 11' 3-7/8" |
| 12x12 lean-to | 2/12 | 9.5° | 2x8 @ 16" | 13' 3-3/8" | 11' 9-5/8" |
Steeper or shallower: what changes
A steeper roof makes the shed taller and adds roof area, so it costs a little more. On a 10x12 gable, going from 3/12 to 12/12 raises the shed from 10' 9-3/8" to 14' 6-5/8" and the roof from 151 to 207 square feet:
| Pitch | Height | Roof area | Rafter length | Materials |
|---|---|---|---|---|
| 3/12 | 10' 9-3/8" | 151 sq ft | 5' 8-5/8" | $3,938 |
| 4/12 | 11' 2-3/16" | 154 sq ft | 5' 10-5/8" | $3,966 |
| 5/12 | 11' 7-1/16" | 158 sq ft | 6' 1" | $4,101 |
| 6/12 | 11' 11-15/16" | 164 sq ft | 6' 3-11/16" | $4,095 |
| 8/12 | 12' 9-15/16" | 176 sq ft | 6' 10-1/16" | $4,083 |
| 10/12 | 13' 8-1/4" | 190 sq ft | 7' 5-1/2" | $4,210 |
| 12/12 | 14' 6-5/8" | 207 sq ft | 8' 1-3/4" | $4,422 |
Height matters for more than looks: some towns limit how tall a shed can be before it needs a permit, or how close a tall one can sit to the property line. Check yours before you pick a steep pitch (see do I need a permit for a shed?).
Roof pitch and snow
Where it snows, rafter size comes from the snow load, not only the pitch. Our plans offer three snow choices: light (a 20 psf roof load), moderate (30 psf ground snow) and heavy (50 psf ground snow), using the building code's rafter tables, which apply the full ground snow load to the roof. Above 50 psf, have the roof designed by an engineer.
| Shed | Light (20 psf) | Moderate (30 psf) | Heavy (50 psf) |
|---|---|---|---|
| 8 ft wide gable, 6/12 | 2x6 | 2x6 | 2x6 |
| 10 ft wide gable, 6/12 | 2x6 | 2x6 | 2x6 |
| 12 ft wide gable, 6/12 | 2x6 | 2x6 | 2x6 |
| 14 ft wide gable, 6/12 | 2x6 | 2x6 | 2x6 |
| 16 ft wide gable, 6/12 | 2x6 | 2x6 | 2x6 |
| 6 ft deep lean-to, 3/12 | 2x6 | 2x6 | 2x6 |
| 8 ft deep lean-to, 3/12 | 2x6 | 2x6 | 2x6 |
| 10 ft deep lean-to, 2/12 | 2x6 | 2x6 | 2x8 |
| 12 ft deep lean-to, 2/12 | 2x6 | 2x8 | 2x10 |
Find your ground snow load from your building department or the ASCE Hazard Tool, then choose the matching option in the calculator.
Lean-to sheds: why 2/12 or 3/12
A lean-to's one slope runs the whole depth, so the front wall must be taller than the back by the full rise. A 10-foot-deep lean-to at 3/12 would need a front wall of more than 10' 0", taller than a 10-foot 2x4 stud allows, so our plans drop deep lean-tos to 2/12, where the front wall is 9' 8-9/16". At 2/12, asphalt shingles need two layers of underlayment, and lapped metal panels would need lap sealant, which is why our plans offer metal only from 3/12.
How to measure the pitch of a roof
- Hold a level horizontal with one end touching the underside of a rafter (or the roof surface).
- Mark 12 inches along the level from that point.
- Measure straight up from the mark to the rafter, or down to the roof: that is the rise, so 4 inches means 4/12.
A phone's angle app works too: read the angle and find it in the chart above (18.4° is 4/12, 26.6° is 6/12).
Questions people ask
What is the best roof pitch for a shed?
There is no single best: it is whatever your roofing allows and your town's height limit leaves room for. Our gable plans use 6/12 (26.6°), steep enough for shingles with one layer of underlayment, and our lean-tos 2/12 or 3/12.
What is the minimum pitch for a shed roof with shingles?
Asphalt shingles need at least 2/12 under the International Residential Code, with two layers of underlayment from 2/12 up to 4/12.
What is the minimum pitch for a metal shed roof?
Lapped metal panels with exposed fasteners need 3/12 without lap sealant, or 1/2 in 12 with it; standing-seam metal can go down to 1/4 in 12 (IRC R905.10.2). Follow the panel maker's own minimum if it is higher.
What is a 4/12 roof pitch in degrees?
18.4 degrees. A 6/12 pitch is 26.6 degrees, 8/12 is 33.7 and 12/12 is 45.
Does a steeper roof cost more?
A little. Our 10x12 gable needs 151 square feet of roof at 3/12 and 207 at 12/12; the materials go from $3,938 to $4,422.
Try another pitch
Change the pitch, snow load and roofing in the free materials calculator and it redraws the rafters and the materials list. The 10x12 gable shed plans include the rafter pattern with every cut angle.
Sources
- California Residential Code (2021 IRC text), Section R905 Requirements for roof coverings: minimum slope for each roofing
- California Residential Code (2021 IRC text), Section R802 Wood roof framing: rafter span tables by ground snow load
- ASCE Hazard Tool: ground snow load for an address
- American Wood Council, 2024 Span Tables for Joists and Rafters: rafter spans by species, grade and load
Our plans and these guides follow common light-frame building practice and are a guide, not drawings stamped for your site: check your local codes, permit rules and HOA before you build.