Typical pitch by use
| Use | Common pitch | Why |
|---|---|---|
| Lean-to against a house or porch roof | 2/12 to 4/12 | Low profile, meets the wall below the eave |
| Garden shed or tool shed | 3/12 to 6/12 | Drains well, leaves headroom, easy to frame |
| Carport | 1/2:12 to 3/12 | Metal panels drain at low slopes |
| Modern shed-roof house | 2/12 to 6/12 | Single slope sets the design |
| Snowy region | 4/12 or steeper | Sheds snow and reduces drift load |
These are common choices, not rules. The material you choose sets the minimum, and local snow load may set the structure.
Rise and rafter length by span
For a shed roof the run is the whole building width, not half of it. The rafter length is run × multiplier and does not include overhang. The rise is how much taller the high wall is than the low wall.
| Width (run) | Rise at 2/12 | Rise at 3/12 | Rise at 4/12 | Rise at 6/12 | Rafter at 4/12 |
|---|---|---|---|---|---|
| 8 ft | 1 ft 4 in | 2 ft 0 in | 2 ft 8 in | 4 ft 0 in | 8 ft 5 1/4 in |
| 10 ft | 1 ft 8 in | 2 ft 6 in | 3 ft 4 in | 5 ft 0 in | 10 ft 6 1/2 in |
| 12 ft | 2 ft 0 in | 3 ft 0 in | 4 ft 0 in | 6 ft 0 in | 12 ft 7 3/4 in |
| 16 ft | 2 ft 8 in | 4 ft 0 in | 5 ft 4 in | 8 ft 0 in | 16 ft 10 3/8 in |
| 20 ft | 3 ft 4 in | 5 ft 0 in | 6 ft 8 in | 10 ft 0 in | 21 ft 1 in |
| 24 ft | 4 ft 0 in | 6 ft 0 in | 8 ft 0 in | 12 ft 0 in | 25 ft 3 5/8 in |
On a 12 ft wide shed at 4/12 the high wall is 4 ft 0 in taller than the low wall, and each rafter is 12 ft 7 3/4 in long before overhang. Add the overhang along the slope: a 12 inch horizontal overhang adds 1.05 ft of rafter.
Roofing by pitch
| Pitch | Angle | Roofing options |
|---|---|---|
| 1/2:12 | 2.4° | Standing seam or sealed-lap metal, membrane |
| 1/12 | 4.8° | Metal with sealant, roll roofing |
| 2/12 | 9.5° | Shingles with double underlayment, metal |
| 3/12 | 14.0° | Shingles with double underlayment, metal panels |
| 4/12 | 18.4° | Shingles, metal, tile with underlayment |
| 6/12 | 26.6° | Almost any steep-slope roofing |
Pick a pitch
- If you will use asphalt shingles, 4/12 avoids the double underlayment rule. See the shingle minimum pitch page.
- If you will use metal, check the metal roof minimum pitch.
- Each step up in pitch makes the roof larger. Use the roof area calculator with the shed option to size the materials.
Cut lengths from the rafter length calculator.
Frequently asked questions
What is the best pitch for a shed roof?
Most sheds use 3/12 to 6/12. 4/12 is a common pick because it allows ordinary shingle installation and drains well.
What is the minimum pitch for a shed roof?
It depends on the roofing: 1/4:12 for standing seam metal, 3:12 for exposed-fastener metal and 2:12 with double underlayment for shingles.
How do I figure the rise of a shed roof?
Multiply the width in feet by pitch divided by 12. A 12 ft wide shed at 4/12 rises 4 ft.
Sources
- Jaspector: IRC 2024 roof slope requirements by covering
- Roof Observations: minimum roof pitch for metal roofing (IRC R905.10.2 summary)