It is a classic gable shed on wood skids: a 2x6 floor, 2x4 stud walls with T1-11 plywood siding, 2x6 rafters on a ridge board, and an asphalt shingle roof. The spans, rafter ties, nailing and clearances come from the International Residential Code, so the shed is built the way an inspector would expect, even where it needs no permit.
How to use this calculator
- Choose the width and the length. The door goes in the front gable, so the width is the side you walk in from. Sizes go up to 12x16, which keeps the floor under 200 sq ft.
- Choose a single door or double doors, and the roof pitch. A steeper roof sheds rain faster and gives more headroom under the ridge.
- Pick the ground snow load where you live. Your building department can tell you; where it is higher than the list offers, the roof needs its own design.
- Take the shopping list to the store, then follow the steps in order. The lumber yard can deliver the long boards.
Worked examples
An 8x10 shed with double doors
Width: 8 ft · Length: 10 ft · Door: Double doors, 5 ft wide
- Your shed
- 80 sq ft of floor
- Outside size
- 8 ft wide, 10 ft long, 10 ft 7 1/8 in to the peak
- Door opening
- 5 ft wide, 7 ft 1 7/8 in high
- Roofing
- 4 bundles of shingles (1.05 squares)
- Boards to buy
- 81
A 10x12 shed
Width: 10 ft · Length: 12 ft · Door: Double doors, 5 ft wide · Roof pitch: 6 in 12
- Your shed
- 120 sq ft of floor
- Outside size
- 10 ft wide, 12 ft long, 11 ft 4 15/16 in to the peak
- Door opening
- 5 ft wide, 7 ft 1 7/8 in high
- Roofing
- 6 bundles of shingles (1.57 squares)
- Boards to buy
- 92
A 12x16 shed with wide doors
Width: 12 ft · Length: 16 ft · Door: Double doors, 6 ft wide · Roof pitch: 5 in 12
- Your shed
- 192 sq ft of floor
- Outside size
- 12 ft wide, 16 ft long, 11 ft 5 1/8 in to the peak
- Door opening
- 6 ft wide, 7 ft 1 7/8 in high
- Roofing
- 8 bundles of shingles (2.37 squares)
- Boards to buy
- 119
A small 6x8 garden shed
Width: 6 ft · Length: 8 ft · Door: Single door, 3 ft wide · Roof pitch: 6 in 12
- Your shed
- 48 sq ft of floor
- Outside size
- 6 ft wide, 8 ft long, 10 ft 4 15/16 in to the peak
- Door opening
- 3 ft wide, 7 ft 1 7/8 in high
- Roofing
- 3 bundles of shingles (0.686 squares)
- Boards to buy
- 63
A 10x16 shed for more snow
Width: 10 ft · Length: 16 ft · Door: Double doors, 5 ft wide · Ground snow load where you live: Up to 30 psf
- Your shed
- 160 sq ft of floor
- Outside size
- 10 ft wide, 16 ft long, 11 ft 1/8 in to the peak
- Door opening
- 5 ft wide, 7 ft 1 7/8 in high
- Roofing
- 7 bundles of shingles (2.01 squares)
- Boards to buy
- 102
How big can a shed be without a permit?
Under the model building code most towns use, a one-story shed with a floor of up to 200 sq ft needs no building permit. Many towns keep that rule, some set a smaller size, and zoning rules about how close you can build to a property line apply either way, so call your building department before you buy lumber.
A shed that needs no permit still has to be built to the code. That is why every span, tie and nail count in this plan comes from the code’s tables.
What holds the roof up
- The rafters are 2x6, 24 inches apart, and each pair is tied across the shed by a 2x4 rafter tie on the wall plates. Without the ties, the weight of the roof would push the walls apart.
- The notch where each rafter sits on the wall leaves at least 3.5 inches of wood above it, as the code asks for a rafter that overhangs the wall. A 2x4 is too shallow for that, which is why the plan uses 2x6 rafters.
- The ridge board is a 2x8, deeper than the sloped ends of the rafters it joins.
- Each joint where a tie meets a rafter gets the number of nails the code’s table gives for your pitch and snow load.
Keeping the shed dry and sound
- The skids, joists and rim joists sit near the ground, so they are ground-contact treated lumber, fastened with hot-dip galvanized nails.
- The siding stops at least 6 inches above the ground, and the gravel pad lets water drain away from the floor.
- Siding joints land on studs, and Z-flashing covers the joint where the gable tops meet the walls.
- At a pitch of 4 in per 12 in or steeper, one layer of underlayment under the shingles is enough. Drip edge along the eaves and up the rakes keeps water off the wood.
Common questions
What is the best foundation for a shed?
For a shed this size, treated wood skids on a compacted gravel pad are the simplest: the gravel drains, the skids spread the weight, and the shed can be moved later. A concrete slab or piers last longer but take far more work.
How far apart should shed rafters be?
With 2x6 rafters, 24 inches on center, which is also the most the code allows between rafter ties. Roof sheathing rated for that spacing spans it without clips.
What roof pitch is best for a shed?
Asphalt shingles need a slope of at least 2 in per 12 in, and from 4 in per 12 in one layer of underlayment is enough. This plan offers pitches from 4 in 12 to 6 in 12: steeper sheds water and snow better and gives more headroom.
How high off the ground should a shed floor be?
High enough that the siding stays at least 6 inches above the ground. Skids on edge on a gravel pad lift the floor frame and leave room for air under it.