Reference chart
Shed roof pitch chart
A 4/12 roof is 18.4 degrees and multiplies rafter run by 1.054. On an 8 ft wide gable shed, 4/12 lifts the ridge 16 in above the walls. Asphalt shingles need at least 2/12 (IRC R905.2.2).
Ridge height is for a gable roof: half the shed width times pitch. Columns show 8, 10 and 12 ft wide sheds (4, 5 and 6 ft of run).
| Pitch | Angle | Rafter factor | Ridge, 8 ft wide | Ridge, 10 ft wide | Ridge, 12 ft wide | Roofing |
|---|---|---|---|---|---|---|
| 1/12 | 4.8° | 1.003 | 4 in | 5 in | 6 in | No shingles; metal or membrane |
| 2/12 | 9.5° | 1.014 | 8 in | 10 in | 12 in | Shingles with double underlayment |
| 3/12 | 14.0° | 1.031 | 12 in | 15 in | 18 in | Shingles with double underlayment |
| 4/12 | 18.4° | 1.054 | 16 in | 20 in | 24 in | Shingles, standard underlayment |
| 5/12 | 22.6° | 1.083 | 20 in | 25 in | 30 in | Shingles, standard underlayment |
| 6/12 | 26.6° | 1.118 | 24 in | 30 in | 36 in | Shingles, standard underlayment |
| 7/12 | 30.3° | 1.158 | 28 in | 35 in | 42 in | Shingles, standard underlayment |
| 8/12 | 33.7° | 1.202 | 32 in | 40 in | 48 in | Shingles, standard underlayment |
| 9/12 | 36.9° | 1.250 | 36 in | 45 in | 54 in | Shingles, standard underlayment |
| 10/12 | 39.8° | 1.302 | 40 in | 50 in | 60 in | Shingles, standard underlayment |
| 12/12 | 45.0° | 1.414 | 48 in | 60 in | 72 in | Shingles, standard underlayment |
Roofing and ventilation
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Other shed reference charts
- Shed size chart
- Equipment footprint chart
- Gravel for a shed pad, by size
- Concrete for a shed slab, by size
- Shed roof snow load table
- Shed paint coverage chart
- Shed permit size thresholds
- Shed cost per square foot
Frequently asked questions
What is a rafter factor?
The rafter factor is the number you multiply the horizontal run by to get the sloped rafter length, before any overhang. It equals the square root of 1 plus the pitch squared, with pitch as rise over 12. At 6/12 it is 1.118, so a 5 ft run needs a 5.59 ft rafter.
This page is researched guidance, not professional engineering, legal or building-code advice. Sizes, loads and permit rules vary by product and by town: check your local code and the kit manufacturer's instructions before you build.