20x20 Shed Material List

A 20×20 shed is garage-size: 400 square feet, enough for a full shop, a vehicle, or serious equipment storage. At this size nearly every jurisdiction requires a building permit, and many will ask for engineered plans — check with your local building department before ordering materials. The list below covers a 20×20 footprint (400 sq ft) and assumes 8-foot walls, a gable roof at a 6/12 pitch, walls framed 16 inches on center, and a framed plywood floor. Every quantity is computed with the same formulas as our shed material calculator — if you want to adjust dimensions or roof style, run your own numbers there.

Complete 20×20 Shed Material List

Prices are approximate U.S. averages — the same unit prices our shed calculator uses — and vary by region, retailer, and lumber market conditions.

How Much Lumber for a 20x20 Shed?

A 20×20 shed with 16-inch on-center walls needs about 64 wall studs plus 30 eight-foot 2×4s for the top and bottom plates. The gable roof takes 22 2×6 rafters at 24-inch spacing, and the floor frame uses 16 2×6 joists at 16 inches on center. For sheet goods, plan on 20 sheets of OSB for wall sheathing, 16 sheets for the 492 sq ft roof deck (including overhang), and 13 sheets of 3/4-inch plywood for the floor — 49 sheets in total — plus 20 sheets of T1-11 siding and 15 bundles of shingles. Buy two or three extra studs for blocking and door framing, and cull any badly crowned boards for cut-up pieces.

Foundation for a 20x20 Shed

A gravel pad should extend 12 inches beyond the shed on all sides, so a 20×20 shed needs a 22×22 gravel pad. At 4 to 6 inches deep, that works out to about 7.2 cubic yards of compacted 3/4-inch crushed stone over landscape fabric — fine-tune the gravel quantity here. If you would rather pour a concrete slab, a 20x20 slab at 4 inches thick takes about 4.9 cubic yards of concrete — roughly 223 80-lb bags, which is well past the point where ready-mix delivery makes more sense than mixing by hand. For a garage-size shed like this one, a slab is strongly recommended — it doubles as the floor, carries vehicle loads, and most permit offices will expect one. Estimate the concrete for a slab here.

Estimated Total Cost

Expect DIY materials for a 20x20 shed to run $2,872 to $6,758. The low end assumes basic framing lumber, OSB sheathing, and 3-tab shingles; the high end reflects plywood sheathing, architectural shingles, and premium siding. That total does not include the foundation, paint or stain, a ramp, or shelving. Budget extra for permit fees and, if required, engineered plans. For a full comparison of DIY builds against shed kits and professional installation, see our shed cost guide.