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Shed roof pitch is how many inches the roof rises for every 12 inches it runs level. Most gable sheds use 4/12 to 6/12. Asphalt shingles need at least 2/12, with double underlayment below 4/12. Start a lean-to at 3/12 to 4/12.

The same numbers apply to a single-slope porch or skillion roof. Wall heights below are worked examples from the 3DSHEDPLANS plan generator, the tool behind our lean-to shed plans and gable shed plans.

What shed roof pitch means: 3/12, 4/12, 6/12

Pitch is written as rise over a 12 inch run. A 4/12 roof climbs 4 in for every 12 in it runs level, measured from the outside of the wall toward the high side (lean-to) or the ridge (gable). It is not measured along the sloped rafter.

As a grade, 4/12 is about 33 percent and 6/12 is 50 percent. Some older framing books use pitch as rise over the full span, so a 6/12 roof shows up there as a “1/4 pitch”; check which one a plan means.

The table turns each common pitch into an angle, a rafter length factor and what it means for roofing. The “rafter per foot” column is the length of rafter for each 12 in of level run, the same number printed on the rafter table of a framing square.

Pitch Angle Rafter per foot of run Asphalt shingles Typical use
2/12 9.5 deg 12.17 in Lowest slope, double underlayment Very low lean-to
3/12 14.0 deg 12.37 in Double underlayment Lean-to sheds
4/12 18.4 deg 12.65 in Single underlayment Lean-to or low gable
5/12 22.6 deg 13.00 in Single underlayment Gable
6/12 26.6 deg 13.42 in Single underlayment Gable and hip sheds
8/12 33.7 deg 14.42 in Single underlayment Steep gable, more snow shedding
12/12 45.0 deg 16.97 in Single underlayment, hard to walk A-frame or steep decorative gable

The same factor gives the rafter length: multiply the level run, including the overhang, by the factor and divide by 12. It also tells you how much roofing to buy. A 6/12 roof has about 12 percent more sheathing and shingle area than its flat footprint, an 8/12 about 20 percent more, and a 12/12 about 41 percent more.

What is the minimum pitch for a shed roof?

The roofing sets the lowest slope you can use. Here is how the common shed roofs line up, from the makers’ own install guides:

  • Asphalt shingles: 2/12 is the lowest slope. From 2/12 up to 4/12, the ARMA guide to shingles on lower-sloped roofs and the GAF low-slope shingle bulletin call for two layers of underlayment over the whole deck. The Owens Corning ProArmor instructions spell it out: a 21 in starter course at the eave, then courses lapped by 22 in, with end laps of at least 12 in on these slopes.
  • Exposed-fastener metal panels: the minimum depends on the profile and on sealant. One maker’s exposed-fastener panel guide lists 3/12 as its minimum, while other profiles go lower only with sealant tape in the side laps. Standing seam panels are often rated lower still. Read the guide for your exact panel.
  • Roll roofing, membranes and clear panels: roll roofing and rubber or TPO membranes are made for low and near-flat roofs, and polycarbonate panels list their own minimum slope. Each product has its own minimum and lap pattern on its label.

GAF also says not to shorten the shingle exposure to make up for a low slope. Lay the shingles at their normal exposure and get the underlayment right instead. In cold areas, ARMA’s low-slope guide also covers a self-adhered membrane at the eave in place of felt. An unheated shed rarely builds ice dams, but your local permit office can tell you if your area expects eave protection.

How pitch changes a lean-to shed

On a lean-to, every inch of rise lands on one wall. The front (door) wall gets taller as the pitch goes up, while the back wall holds its height until the front wall hits a cap.

Our generator starts lean-to sheds with an 80 in back wall, including the plates. It caps the front wall at about 118 in to keep it within 10 ft stock. When a steeper roof would push the front wall past that, the generator lowers the back wall instead.

Lean-to depth Pitch Rafter Back wall Front wall Difference
8 ft 3/12 2×4 80 in 103 in 23 in
8 ft 4/12 2×4 80 in 110 13/16 in 30 13/16 in
10 ft 3/12 2×6 80 in 109 in 29 in
10 ft 4/12 2×6 79 1/2 in 118 5/16 in 38 13/16 in
12 ft 3/12 2×6 80 in 115 in 35 in
12 ft 4/12 2×6 71 1/2 in 118 5/16 in 46 13/16 in

These rows come from the 3DSHEDPLANS generator’s lean-to model, with wall heights including the plates and SPF #2 rafters at 16 in on center sized for a 30 psf ground snow load. They are examples for comparison, not the numbers of a plan we sell, so use your own plan’s rafter size.

Look at the 12 ft deep rows. Going from 3/12 to 4/12 drops the back wall from 80 in to 71 1/2 in, so the back of the shed loses headroom you would notice with shelves or a workbench. That is why most lean-tos stay at 3/12 to 4/12, and why deeper lean-tos sit at the low end of the range.

Single underlayment needs 4/12, which on a 12 ft deep lean-to costs about 8 1/2 in of back wall. Low lean-tos with deep overhangs also catch wind under the eave, so tie each rafter to the wall plate with a metal connector and check your local permit office for local wind rules. For the full build, see how to build a lean-to shed.

How pitch changes a gable or hip shed

A gable splits the rise between two slopes, so each rafter only climbs over half the shed’s depth. A steeper gable raises the ridge, not the walls. This is why gable sheds can run 6/12 and steeper without awkward wall heights.

Here is how high the ridge sits above the top of the wall plates, measured at the plate line, with a ridge board 1 1/2 in thick. Depth is measured wall to wall, outside of the framing. The top of the ridge sits a few inches higher, by the rafter’s depth above the plate.

Shed depth (wall to wall) 4/12 6/12 8/12
8 ft 15 3/4 in 23 5/8 in 31 1/2 in
10 ft 19 3/4 in 29 5/8 in 39 1/2 in
12 ft 23 3/4 in 35 5/8 in 47 1/2 in

A taller ridge gives more room overhead for light storage, but not a walk-in loft; a loft needs its own floor joists sized in the plan. A steeper roof also needs longer rafters: a 10 ft deep gable at 8/12 uses rafters about 7.5 percent longer than at 6/12, from the rafter column in the first table.

Hip sheds use the same pitch on all four sides. Our hip generator uses 6/12, and the hips climb 6 in for every 17 in of run. See hip roof shed framing for the hip and jack cuts.

How to choose the right pitch for your shed

Work through these in order:

  1. Roofing. Shingles below 4/12 mean double underlayment, and below 2/12 they are out. For metal, start from the panel’s listed minimum.
  2. Snow and rain. A steeper roof lets go of snow sooner, and on any slope a drip edge keeps runoff off the fascia. Rafter size and spacing still carry the load: use the rafters in your plan or size them with the American Wood Council span calculator, and check your local permit office for the design snow load where you live.
  3. Height. Some towns cap shed height or measure it in a set way, and a steeper roof raises the peak. Check your local permit office before you settle on a pitch.
  4. Headroom. On a lean-to, check the low wall against what you will store along it. On a gable, decide if you want overhead storage.
    Once you pick a plan, build at its pitch. A 3DSHEDPLANS plan PDF draws the roof framing in 3D with the rafters in its material list, and changing the pitch means new rafter cuts for every rafter and, on a lean-to, new wall heights.

How to measure an existing roof pitch

Work from a ladder at the gable end or on an exposed rafter inside, not on the roof. Hold a 2 ft level flat and level, with one end touching the rafter and the bubble centered. Mark 12 in out from that end. Measure straight down from the mark to the rafter: that number is the rise, so 4 in means 4/12.

A digital angle finder set on a rafter reads the angle in degrees; match it in the first table. To read the pitch off a plan, divide the rise by the run and multiply by 12: a roof that climbs 30 in over a 120 in run is 3/12.

Common mistakes with shed roof pitch

  • Measuring the pitch along the sloped rafter instead of on the level. The run is always horizontal.
  • Shingling a 3/12 lean-to over one layer of felt. The ARMA and GAF guides above both call for two layers below 4/12.
  • Making a lean-to steeper without redoing the walls. Each extra 1/12 on a 12 ft deep shed adds about 12 in to the front wall or takes it from the back.
  • Cutting rafters before testing one pattern rafter on the actual walls. The plumb cut angle is the angle in the first table; on a speed square, pivot to the pitch number on the COMMON scale and mark.
  • Pointing the low edge of a lean-to at the door or a neighbor’s fence. Our generator puts the door in the tall front wall so the runoff goes out the back.

Plans that fit

Each plan below is a 3DSHEDPLANS PDF with 3D framing views and a full material list.

What we checked: angles, rafter factors and ridge heights are plain trigonometry (ridge run is half the depth minus half the ridge thickness); shingle slopes come from the ARMA and GAF guides; underlayment laps from the Owens Corning instructions; metal from the panel maker’s guide; lean-to wall heights from our plan generator.

Still deciding on a roof style? Read gable vs lean-to vs hip roof or how to build a shed roof, or browse all 3DSHEDPLANS shed plans.

Frequently asked questions

What is a good roof pitch for a shed?

For a gable or hip shed with asphalt shingles, 4/12 to 6/12 is the usual range, and our gable plan generator uses 6/12. A lean-to usually runs 3/12 to 4/12 so its tall wall stays a buildable height. Go steeper where snow is heavy and the plan's rafters allow it.

What is the minimum pitch for a shed roof with shingles?

Asphalt shingle makers and the Asphalt Roofing Manufacturers Association list 2/12 as the lowest slope for shingles. From 2/12 up to 4/12 they call for a double layer of underlayment. Below 2/12, use a roofing product rated for low slopes.

Is a 3/12 pitch enough for a shed roof?

Yes, for shingles laid over two layers of underlayment, or for metal panels whose install guide lists 3/12 or lower. It is a common lean-to slope because it keeps the tall wall low.

How do you calculate the pitch of a shed roof?

Divide the rise by the run and multiply by 12. A lean-to whose roof climbs 30 in over a 120 in run has a pitch of 30 / 120 x 12 = 3, so 3/12. On a gable, measure the run from the wall to the center of the ridge.

Can a shed roof be flat?

Not with shingles or most screw-down metal panels. A nearly flat roof needs a membrane or panel made for low slopes, laid exactly as its maker says. For a backyard shed, 2/12 or steeper keeps the roofing choices simple.

Shed building guides