Mark out an area 150 mm (6 in) bigger than your shed on every side. Dig out 100–150 mm, level and firm the soil, then build a treated timber frame and peg it level. Lay weed membrane inside, fill with about 100 mm of 20 mm angular gravel, compacting it in two layers, and sit the shed on treated bearers. For an 8×6 shed, expect to spend roughly £190–£300 on materials and a weekend of work.
Why a gravel base?
A gravel base is the friendliest foundation for a first shed. It's cheaper than concrete, needs no mixing or curing time, and — the big one — it drains. Rain runs straight through the stone instead of pooling under the floor, which is what rots most cheap sheds from the bottom up.
It suits timber, metal and plastic sheds up to about 10×8 ft on reasonably flat ground. If your garden slopes more than a hand's width over the length of the shed, or you're putting up a heavy workshop with a stove and benches, read about concrete or raised timber bases first.
What's in the base
Here's a slice through a finished base. Nothing clever: a frame to hold the stone in, a membrane to stop weeds and stop the stone sinking into the soil, the gravel itself, and bearers to lift the shed floor clear of it all.
Materials list
Quantities are for an 8×6 ft (2.4 × 1.8 m) shed, so a finished base of about 2.7 × 2.1 m. Tick things off as you buy them — your ticks are saved on this device.
Tools: spade, rake, tape measure, spirit level (1.2 m or longer), a straight timber offcut, drill/driver, saw, sledgehammer or club hammer, and a hand tamper or hired plate compactor.
Step by step
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Choose the spot
Pick the flattest, best-drained part of the garden you can, with room to walk round all four sides — you'll need it for treating the timber and fixing the roof. Keep the shed away from overhanging trees, and check your local rules on height and distance from boundaries before you dig.
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Mark it out and square it
Peg out a rectangle 150 mm larger than the shed on every side (2.7 × 2.1 m for an 8×6). Run string between the pegs, then measure both diagonals. When the two diagonals match, the rectangle is square.
TipNo long tape? Use 3-4-5: measure 3 units along one side, 4 along the other — the corner is square when the gap between those marks is exactly 5.
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Strip the turf and dig out
Lift the turf and dig the whole area down 100–150 mm, taking out roots and soft spots. Rake the soil roughly level and walk it firm, or go over it with the tamper. If it's very soft clay, add 50 mm of MOT Type 1 sub-base and compact it before going further.
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Build and level the frame
Screw the four frame boards together into a rectangle, three screws per corner. Set it in the hole, drive a stake inside each corner and mid-way along each side, and screw the frame to the stakes. Work round with the spirit level, raising or tapping down until the top edge is level both ways, and check the diagonals again.
TipLevel the frame, not the soil. Once the frame is true, the gravel just needs screeding to its top edge.
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Lay the weed membrane
Cut the membrane to cover the floor of the frame and run 50–100 mm up the inside of the boards. Overlap joins by at least 300 mm. Staple the edges to the frame so it doesn't creep while you fill.
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Fill with gravel, in two layers
Barrow in half the gravel, rake it level and compact it. Then add the rest, compact again and drag a straight timber across the frame to screed the top flush. Two thin compacted layers stay put far better than one thick loose one.
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Set the bearers
Lay treated bearers across the gravel at the spacing your shed floor needs (usually no more than 600 mm apart), running across the shortest span of the floor joists. Check they're level with each other; nudge gravel under any low spots rather than packing with offcuts.
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Final check, then build
Lay the level across the bearers in a few directions. If the bubble's centred, you're done — put the floor on and build the shed. Leave a gap between the cladding and the gravel so splash-back doesn't soak the bottom boards.
What it costs
These are sample estimates for an 8×6 base using UK builders' merchant prices as of late 2026. Prices vary a lot by region and supplier — use this as a shopping checklist and get your own quotes.
| Item | Qty | Low | High |
|---|---|---|---|
| Treated 150×47 mm timber, 3.0 m | 4 | £48 | £68 |
| Treated stakes 50×50×600 mm | 8 | £12 | £18 |
| Exterior screws, 5×90 mm | 1 box | £8 | £12 |
| Weed membrane, heavy-duty | ≈ 8 m² | £12 | £22 |
| 20 mm gravel, bulk bag | 1 | £70 | £100 |
| Treated bearers 75×50 mm (if needed) | 4 | £20 | £28 |
| Hand tamper buy or plate compactor hire (1 day) | 1 | £20 | £55 |
| Estimated total | £190 | £303 |
For comparison, a concrete slab the same size usually costs more in materials alone and takes days to cure; paving slabs on a sub-base land somewhere in between.
Example picks
A couple of things that make this job easier. These are examples of the kind of product to look for — compare a few before you buy.
Woven ground-cover membrane, 100 g/m²+
Woven polypropylene lasts far longer under stone than spun "fleece". Look for a UV-stabilised roll at least 2 m wide.
Check pricesSteel hand tamper, 200×200 mm plate
Fine for one small base and cheaper than a day's compactor hire. For anything over 10×8, hire the plate compactor.
Check pricesFAQ
How deep should a gravel shed base be?
75–100 mm (3–4 in) of compacted gravel is plenty for a typical garden shed. Dig 100–150 mm so the top of the stone sits roughly level with the surrounding ground or slightly above it.
What type of gravel is best?
Angular crushed stone around 20 mm (often sold as "20 mm clean stone" or "20 mm gravel"). The sharp edges lock together when compacted. Avoid round pea shingle — it rolls about like marbles and never firms up.
Do I really need the weed membrane?
Yes. It stops weeds pushing through, and it stops the gravel slowly sinking into the soil, which is what makes bases go out of level after a couple of winters.
Can the shed sit straight on the gravel?
Not directly. The floor should sit on treated bearers so air can move underneath and the floor isn't sitting in damp stone. Many sheds come with bearers already fixed under the floor — check before you buy extra.
Is gravel strong enough for a big or heavy shed?
For most sheds up to around 10×8 ft, yes. For large workshops, log cabins, or anything with heavy machinery, a concrete slab or a properly designed timber base is the safer call.
Planning the rest of the shed?
The free Shed Review Guide has a printable base & size planner and a 20-point checklist for judging the shed you put on it.