Calculators / Sheds, pergolas and gazebos
What does your shed foundation need?
Put in the shed size and the kind of foundation. You’ll get exactly what to buy, from the shed makers’ own install guides.
Updated · How we check our numbers
Your shed foundation
3.2 tons of crushed stone
A 12 × 14 ft pad, 12 in past the shed on every side (Keter), 4 in deep: 2.3 cubic yards with 10% for compaction.
- Pad
- 12 × 14 ft
- Gravel
- 2.3 yd³3.2 tons
Estimate for planning only, not professional advice. Check the manufacturer’s instructions, your local code and a licensed professional before you buy, build or install. Use at your own risk. Terms.
Price the gravelTons and bags for this pad.
What to get
10 × 12 ft shed- Dig out12 × 14 ft, 4 in deep2.1 yd³
- Crushed stone1.4 tons a cubic yard, compacted in layers3.2 tons
- Border boardsTreated 2x6 or landscape timbers around 52 ft of edge52 ft
From Keter, Heartland, Handy Home, Suncast and Arrow install guides.
Keter: “use pea gravel or gravel smaller than 1/2" so it does not affect the floor.” Compact it in thin layers with a plate compactor.
Many places skip a permit for a one-story shed up to 200 sq ft (Ohio’s residential code, and cities like Hopkins, MN), but setbacks still apply. Check with your building department.
How we work it out
Gravel pad. Keter digs out 4 to 6 in, fills it with compacted gravel smaller than ½ in, and makes the pad 12 in wider than the shed on every side so water runs off. We add 10% for compaction and turn yards into tons by the stone's weight.
Concrete blocks. Heartland sets solid blocks 12 in in from each corner, no more than 72 in apart along a floor joist and 48 in between joists, and publishes the count for each of its sizes, which we use: 16 for a 10 × 12, 22 for a 12 × 16.
Skids. Handy Home runs treated 4x4s 12 in in from the edge and no more than 48 in apart. Slab. Suncast and Arrow call for at least 4 in of concrete, Arrow over 4 in of tamped gravel, and Suncast recommends rebar. Heartland anchors the shed with ½ in wedge anchors 12 in from the corners and 4 ft apart.
Makers disagree on the best base: Keter calls gravel the most popular, Tuff Shed says most of its sheds don't need concrete, and Handy Home recommends a slab or solid blocks over piers. Your shed's manual, and its warranty, have the last word.
Where the numbers come from
Guides
Shed
Materials
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