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The base is the foundation your garden shed stands on. Think of it as its main support, keeping it off the ground to stay stable and level while helping to prevent moisture-related problems. Building one takes a few considerations and steps, and this guide walks you through them. Ready?
Things to Consider When Building a Shed Base
Is the ground where the base will be built level? If not, you’ll need to clear away any debris, like dead plants, weeds, or compact soil, to flatten it. Trying to level a base on bumpy or sloped ground is a lot more of a hassle, don’t you think?
Drainage is also crucial—it’s basically how water flows away from an area (in this case, where the base and your shed will be), instead of pooling. See if water pools in your chosen location and takes ages to drain; if it puddles, it means poor drainage. Fortunately, adding a layer of gravel helps by creating space for water to flow through instead of collecting underneath or around.
Lastly, decide what kind of shed base type you want to build. You’ve got a few options, with the most common being concrete slabs and paving stones for most wooden sheds.
- A concrete slab is a crushed stone material poured directly onto the ground. Once hardened, this layer acts as support between the existing soil and the slab itself.
- Paving stones are a mix of gravel, sand, and sometimes finer crushed stones. This mixture is compacted to create a level and stable surface.
Quick-fit base kits are a great alternative too. These are ready-to-use foundation systems that, once placed on the ground and interlocked, form a solid, level surface for the shed to sit on. You could even build straight on your lawn or mulch with a base such as these.
A great example is the Ecobase Fastfit Foundation Base. Just fill each grid system with gravel, like pea gravel, that’s at least 10mm in diameter, and you have a base.
Now, onto actually building the shed base!
How to Build a Shed Base
These steps work for concrete slabs and paving stones, but feel free to skip them if you’re using a quick-fit base kit.
Mark your shed space
Measure your shed’s size in feet or metres—whichever you prefer. For example, if it’s 8ft × 6ft (2.44m × 1.83m), mark out the area using stakes to outline the base and corners.
Level the ground (again)
Even if you’ve already done it before, it helps to do it again just to make sure the ground within the marked area is level. Remove any high spots and fill in any low areas using a shovel, rake, or levelling tool to get a flat surface.
For concrete shed base construction
Follow these steps after the first two above:
- Excavate the area by digging a trench for the concrete slab (at least 4 inches deep).
- Fill the trench with gravel to a depth of at least 2 inches for proper drainage.
- Create a wooden formwork that matches the shed’s dimensions to contain the concrete.
- Prepare the concrete mix according to the manufacturer’s instructions and pour it into the formwork.
- Level the surface with a screed board and smooth it out with a float.
- Let the concrete cure for at least 48 hours before positioning your shed on top of it. Use a plastic sheeting or tarpaulin (optional) as a cover from rain or extreme sunlight.
And you’re done!
For paving slabs shed base construction
- Excavate the area by digging a trench for the slabs (at least 2-3 inches deep).
- Fill the trench with gravel with a 1-inch layer of sand and compact it to create a solid base.
- Lay the slabs in the desired pattern, levelled and spaced evenly.
- Adjust and align using a rubber mallet and a spirit level accordingly,
- Fill the gaps between the slabs with fine sand so they lock in place.
You don’t need to cure paving slabs in the same way as poured concrete. However, if you’re laying them with a mortar or concrete bed, the mic will need time to set. Avoid walking on them for at least 24-48 hours and allow the mortar to fully cure (5-7 days) before putting the shed on top.
That’s it! For advice on starting your shed journey, read our shed buying guide.
