The short answer
Dig out 100 to 150 mm of soil over an area 150 mm bigger than the shed on every side. Fix a level frame of treated timber in the hole, line it with weed membrane, then fill with angular gravel in two compacted layers. Sit the shed on its bearers, not on the stones directly. For an 8 by 6 shed, budget roughly £230 to £350.
Is gravel right for your shed?
Gravel suits most timber, metal and plastic sheds up to about 10 by 8 on reasonably flat ground. Water runs straight through it, so the floor stays drier than it would on a slab that puddles. If the base ever needs adjusting, you can rake it out and start again, which you can't do with concrete.
It's a poorer choice on a steep slope, where a raised timber frame on posts is less digging. It's also wrong for a heavy workshop with a ride-on mower or a lathe, which needs a concrete slab.
Materials and tools
Quantities are for an 8 by 6 ft shed, which needs a base of about 9 by 7 ft (2.75 by 2.15 m). Tick things off as you buy them. The list is saved on this device.
Materials
Tools
The steps
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Mark out the base
Add 150 mm to every side of the shed's floor size and peg out that rectangle with string. Measure both diagonals: when they're equal, the corners are square. Leave at least 600 mm between the base and any fence or wall so you can get round to treat the timber later.
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Strip the turf and dig out
Lift the turf and dig down 100 to 150 mm across the whole area, keeping the bottom as flat as you can. Go deeper on soft or clay soil. Pile the soil somewhere useful: it makes a good start to a raised bed.
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Level and firm the ground
Rake out the high spots, pull out roots and big stones, then compact the soil. Don't fill dips with loose topsoil, because it will settle. Leave them for the gravel to fill.
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Build the frame and fix it level
Screw the four timbers into a rectangle and drop it into the hole. Check the diagonals again, then drive a peg inside each corner and halfway along each side. Level the top edge in both directions, digging out or packing under the timber as needed, and screw it to the pegs.
This is the step that matters. The top of the frame is the level you'll screed the gravel to, so get it right here and everything after is easy.
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Lay the weed membrane
Roll the membrane across the bottom and up the inside faces of the frame, overlapping joins by 150 mm. Staple it to the inside of the timber so it can't slip down as you fill.
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Fill and compact in two layers
Tip in half the gravel, rake it level and run the compactor over it two or three times. Then add the rest and compact again. Two thin layers pack down far better than one thick one.
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Screed the top level
Drag a straight timber across the frame, resting on both sides, to scrape the gravel flush with the top edge. Fill any low spots, compact once more and check with the level.
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Set the bearers and the shed
Lay the shed's bearers across the short width, roughly 400 to 500 mm apart, and check that each one is level. Pack any low spot with plastic shims, not timber offcuts, which rot. Then build the shed on top.
How much gravel do you need?
Enter your shed's floor size. The calculator adds 6 inches on every side for the base.
What it costs
These are sample estimates for an 8 by 6 shed, based on typical UK builders' merchant and hire prices in late 2026. Prices vary by area and delivery charge, so check locally before you order.
| Item | Quantity | Low | High |
|---|---|---|---|
| Angular gravel, 20 mm | 2 bulk bags | £110 | £170 |
| Treated timber, 150 × 47 mm | 4 × 3.0 m | £50 | £70 |
| Woven weed membrane | about 7 m² | £15 | £25 |
| Timber pegs | 8 to 12 | £10 | £15 |
| Exterior screws | 1 box | £8 | £12 |
| Plate compactor hire | 1 day | £35 | £55 |
| Total | £228 | £347 | |
The biggest saving is the compactor: if you can borrow a hand tamper and have a free afternoon, take £35 to £55 off. The biggest cost risk is delivery. Some merchants charge as much to drop the bags as the gravel costs, so ask before you order.
Kit we'd look at
Not essential, but these make the job easier or the base last longer. They're example picks of the kind of product we'd recommend, and the links are affiliate links.
Plastic gravel grid panels
Interlocking honeycomb panels that sit inside the frame and stop the gravel shifting under the bearers.
Check current pricesWoven ground membrane, 100 g/m²
Heavier than garden-centre fabric. It won't puncture when you tip stone on it.
Check current prices1.2 m builder's spirit level
Long enough to span the frame corner to corner, so you level the whole base, not just one patch.
Check current pricesQuestions
How deep should a gravel shed base be?
100 mm of compacted gravel is enough for most garden sheds on firm ground. Go to 150 mm on clay, soft soil or for a larger shed over 10 by 8.
Do I really need the timber frame?
Yes, for anything bigger than a small storage box. Without it the gravel spreads out at the edges, the corners sink and the shed starts to rack, which is when doors stop closing.
Can I use pea shingle instead of crushed stone?
It's best not to. Pea shingle is rounded, so it rolls under load and never compacts. Angular crushed stone locks together into a firm layer.
Can the shed floor sit straight on the gravel?
Don't do it. Keep the floor on treated bearers so air can move underneath. A floor laid flat on stone stays damp and rots from below.
How long does it take?
Two people can usually build an 8 by 6 base over a weekend: digging and the frame on day one, membrane, gravel and levelling on day two. Allow longer if you're barrowing the gravel a long way.
Do I need permission to build a shed base?
A gravel base on its own rarely needs any permission. The shed's height and position might, especially near a boundary or in a conservation area, so check with your local council before you start.