AlexA concrete shed foundation is the heaviest of the common bases and the least forgiving. A 10 × 12 shed sits on 120 square feet, and that area has to be flat, drained, and able to carry the load. Concrete, blocks, a gravel pad, and a steel base kit are the usual ways to provide it.
This page compares what each one is, what a unit of it costs at one store on one day, and what the price does not cover. It does not tell you which base your shed needs. That depends on your soil, your slope, your climate, and your local rules.
What a shed base has to do
Three jobs, and every option below is judged on the same three:
- Keep the floor off wet ground. Wood in contact with damp soil fails early, whatever it cost.
- Stay level. A base that settles unevenly racks the walls and stops the doors closing.
- Spread the load. The shed, the floor, and everything you put inside have to reach undisturbed soil.
A base that does all three badly is not cheaper. It is deferred.
Prices at one store on one day
| Material | What one unit is | Price | Listing |
|---|---|---|---|
| Concrete mix, 60 lb bag | 60 lb bag | $4.85 | Quikrete 60 lb. Concrete Mix |
| Hollow concrete block, 8 x 8 x 16 in | each | $2.38 | 8 in. x 8 in. x 16 in. Concrete Block |
| Concrete deck block | each | $9.32 | 10-3/4 in. x 10-3/4 in. x 7-3/4 in. Concrete Deck Block |
| Paver base, 0.5 cu. ft. bag | 0.5 cu. ft. bag | $6.47 | Pavestone 0.5 cu. ft. Paver Base |
| Steel base kit for a 10 x 12 shed | kit | $151.05 | Arrow Base Kit for 10 x 12, 10 x 13 & 10 x 14 Sheds |
Scroll the table sideways to read every column.
One store on one day, before tax and delivery. Bulk and credit-card offers are excluded. These are unit prices, not a quantity for your shed.
Retailer links below are the source of these figures, not paid placements. Shed Planner earns no commission on them — see the affiliate disclosure.
Concrete
Concrete reaches the site in two different ways, and only one of them has a shelf price.
Bagged mix is what the table above prices. You buy it by the bag, mix it on site, and place it yourself. It suits small pours: pads under blocks, footings for posts, a short pier.
To put that in numbers: at an example thickness of 4 inches, a 10 × 12 slab is 40 cubic feet, which is about 89 bags of 60 lb bag concrete mix at the manufacturer’s published yield of 0.45 cubic feet per bag. Four inches is the thickness used to work the example, not a thickness this page recommends for your shed.
That is the arithmetic, not the job. Mixing that many bags by hand is a different undertaking from carrying them, and concrete does not wait while you work.
Ready-mix arrives in a truck and is sold by the cubic yard. This page does not quote a price for it, and that is deliberate: ready-mix is a quote from a batch plant, not a shelf item. What you pay depends on the load size, the distance, the mix specified, whether you hit the plant's minimum load, and what the driver has to wait for. A number taken from someone else's slab in another state would tell you nothing.
A poured slab is also the base that is hardest to undo. It changes drainage, it is expensive to remove, and in some places it changes whether the shed is exempt from a building permit at all — the permit page shows one city whose exemption is written around a slab on the ground. Check your own jurisdiction before you pour.
Blocks
Blocks are the low-commitment answer: individual units set on prepared ground, carrying a wood frame above.
A standard concrete block is the rectangular unit used in walls. It is cheap per unit and widely stocked, but it is not shaped to hold anything. Whatever sits on it has to be positioned and held some other way.
A deck block is cast with notches on top, sized to seat a 4x4 post or a 2x dimensional member. That notch is the whole difference: it locates the framing instead of leaving it to friction. At the prices in the table it costs about four times what a plain block costs, for a reason.
Blocks still need the ground under them prepared, and they still need to end up level with each other. The block price is the cheapest part of a block foundation.
A manufactured base kit
The kit in the table is an Arrow accessory, and that is the first thing to know about it. On the manufacturer's own site it is configured under one product line — Arrow sheds — and the sizes offered are Arrow shed sizes. It is not a general-purpose base for whatever shed you buy.
The manufacturer is also specific about what the kit is for. ShelterLogic, which owns the Arrow brand, writes: "Starting off square and level is essential to a successful shed assembly and we recommend that you consider a base kit to self-square the shed and help level the site." Squaring and levelling, in other words — not carrying the shed across soft ground.
And the kit is framing only. The same manufacturer describes the family this way: "Arrow floor frame kits provide the galvanized metal framework foundation to add a strong floor if your shed is placed on grass, gravel, or bare earth. Comes with METAL FRAMING ONLY." The deck you lay on it is a separate purchase, and the ground under it still has to be prepared. Both quotes checked October 18, 2026.
The manufacturer sells base kits and floor frame kits in one family, under one family model number, so the two names are not a reliable way to tell products apart. Check the model against your own shed before ordering.
A gravel pad
A gravel pad is a shallow excavation filled with compacted stone. It drains, and it can be levelled accurately.
The table above prices paver base, which is one of the materials used for a pad and not the only one. Crushed stone sold by grade — the kind a contractor orders by the ton — is the other common choice, and this page does not price it yet, because no crushed-stone price was collected at the reference store. What the store did stock in bags beside the paver base was decorative landscape rock, which is a different product for a different job. Do not read the paver base price as the price of a gravel pad.
The bag unit is also almost useless on its own, because a pad is measured in cubic feet or cubic yards, not in bags. Work out the quantity first with the gravel calculator for a shed base, then multiply.
Buying a pad in bags is convenient for a small shed and expensive for a large one. Past a certain size, bulk delivery is the cheaper form of the same material — and that, like ready-mix, is a quote rather than a shelf price.
What none of these prices covers
Every number on this page is a unit price for a material. A finished base also needs some mix of:
- excavation, spoil removal, and grading;
- compaction, in layers, with a plate compactor you may have to rent;
- a geotextile or weed barrier under stone;
- edging or forms to hold the shape;
- anchors, straps, or ground screws, where wind requires them;
- delivery, tax, and your own hours.
Ask for each of those as a separate line, or mark it unknown. Rolling them into one guessed total is how a base ends up costing twice the material. The cost guide keeps the site base as its own budget row for that reason, and DIY, Kit, and Installed shows which of the three paths leaves the base with you.
Before you choose
Answer these in order, and the choice usually makes itself:
- What does the shed manufacturer require, in writing, for the warranty to hold?
- What does your jurisdiction require, and does the base type change the answer?
- How level is the ground now, and how much has to be cut or filled?
- Is the site wet, and where does the water go after you change the surface?
- Do you want this base to be removable?