The foundation is the least exciting decision in a shed project and the one that decides how the shed ages. Get it right and the doors still close in ten years. Get it wrong and you'll be fighting damp, a racked frame and a sticking door long before the roof needs attention.
Here's an honest comparison of the seven common options — what each costs in money and effort, and when to choose it.
First, what a shed foundation actually has to do
Whatever you build, it needs to:
- Spread the load so the shed doesn't sink unevenly.
- Keep timber off wet ground — moisture is what rots sheds.
- Drain water away rather than trapping it underneath.
- Sit level and square, because every error above is multiplied by it.
Those four jobs are the scorecard for everything below.
1. Compacted gravel pad
A bed of compacted crushed stone, usually retained by a simple timber frame, with the shed sitting on skids on top.
- Best for: most small and medium sheds; the default sensible choice.
- Pros: inexpensive, superb drainage, hand-tool friendly, forgiving to level.
- Watch: must be properly compacted, and it wants a retaining edge or the stone migrates.
This is the option that gives the most durability per pound spent.
2. Pressure-treated skids
Long treated timbers (often 4×4 or larger) laid under the floor frame, usually on top of gravel.
- Best for: smaller sheds, and any shed you might want to move later.
- Pros: cheap, simple, and makes the shed draggable if it needs relocating.
- Watch: skids sitting directly on soil will eventually rot — put them on gravel, not dirt.
Sheds on skids are also far easier to relocate, as our guide to moving a shed explains.
3. Concrete deck blocks
Precast blocks — often notched to accept timber — set on compacted ground or gravel to support the floor frame.
- Best for: small to mid-size sheds where you want the floor lifted and ventilated.
- Pros: quick, no mixing, easy to level individually, good airflow underneath.
- Watch: they can settle if the ground beneath isn't compacted; spacing must suit your joist span.
4. Concrete piers
Poured concrete footings, sometimes in tube forms, set into the ground to carry posts or beams.
- Best for: larger or heavier sheds, sloping sites, and cold climates.
- Pros: very strong, handles slopes well, and can be taken below the frost line where that matters.
- Watch: more work, more layout precision, and frost depth is a local question — ask your building department.
5. Concrete slab
A poured, reinforced pad that acts as both foundation and floor.
- Best for: workshops, heavy equipment, vehicles, and permanent buildings.
- Pros: the most durable, perfectly level, no floor to rot, ideal for rolling machinery.
- Watch: the most cost and effort, effectively permanent, and cold and hard underfoot unless finished. It also usually needs proper preparation and drainage — worth getting help if you haven't poured before.
Note that a slab is your floor, which changes the rest of the build — see does a shed need a floor? for how the two decisions interact.
6. Plastic grid / paver base systems
Interlocking plastic grids filled with gravel, or a bed of paving slabs.
- Best for: small, light sheds and DIYers who want a tidy, quick base.
- Pros: fast, level, drains well, no concrete work.
- Watch: load limits are real — check the product against your shed's weight — and the ground below still needs preparing properly.
7. Bare ground (the one to avoid)
Setting the shed straight onto soil or grass.
- Reality: it costs nothing and fails fastest. Moisture wicks into the timber, the shed settles unevenly, and doors and windows stop working.
- If budget is truly the constraint: even a modest gravel pad is a large improvement for a small outlay.
Quick comparison
| Option | Cost | Effort | Drainage | Best for |
|---|---|---|---|---|
| Gravel pad | Low | Low–Med | Excellent | Most sheds |
| Skids | Low | Low | Good (on gravel) | Small / movable |
| Deck blocks | Low–Med | Low | Good | Small–mid, ventilated floor |
| Concrete piers | Med | Med–High | Good | Large, sloped, frost areas |
| Concrete slab | High | High | Good (if graded) | Workshops, heavy loads |
| Plastic grid / pavers | Low–Med | Low | Good | Small, light sheds |
| Bare ground | None | None | Poor | Not recommended |
How to choose in three questions
- How heavy is the shed and what's going in it? Vehicles and machinery push you toward slab or piers; storage doesn't.
- What's the ground like? Sloped or soft ground favours piers. Flat and firm suits gravel.
- How permanent is it? Skids and gravel keep options open; a slab is forever.
Get the size right first
Foundation work follows the footprint, so settle the size before you dig. Our Shed Size Calculator recommends a footprint from what you'll actually store, the shed size guides show what each common size fits, and the Material Calculator prices the structure that sits on top.
One last note: foundation type, height and placement can all affect permit and setback requirements, and rules vary by location — confirm with your local building department before you build. See our disclaimer for the usual caveat that this is general guidance, not code advice.