Last modified: August 24, 2023

How to Prepare and Build a Shed Base – Ultimate Guide

How to Prepare and Build a Shed Base – Ultimate Guide


How to Prepare and Build a Shed Base – Ultimate Guide

How to Prepare and Build a Shed Base – Ultimate Guide

Written by Garden Buildings Direct
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Shed pictured: The BillyOh 20 Range


A shed base is an essential part of building a shed (whether they may be wooden or metal garden sheds), the base has to be properly made to give your shed a solid foundation. On the face of things, building a shed base or any other building for that matter such as cheap summer house, log cabin, or simple garden storage might seem like a daunting task, but follow these simple steps and your storage sheds will be level and sturdy base in no time at all.

Plan Where Your Shed Will Be Located

  • Make sure there’s access (for delivery and access to all sides for maintenance and applying wood treatments etc.)
  • Surrounding area conditions (Foliage, young trees that may grow in the future)
  • Natural light (a well-lit area is best if the building is to be used as a workshop for example)
  • The view of your garden from the planned area (for summerhouses etc.)
  • Consider whether you intend to run an electrical supply to the building.

Choose the Type Of Base

It’s crucial to provide a level and dry foundation for everything from garden sheds to wooden playhouses after checking whether you are free to build a shed base without a permit. Never assemble a wooden shed base kit on an unsound base, otherwise, you are running the risk that the screw holes connecting the wall panels will not line up. For larger buildings, especially if you’re going to use the shed as a workshop, using a full concrete base as your timber shed base is your best option. However, generally, there are two types of shed bases suitable for a garden building, consider which is best for you…

So what are the shed floor choices? There are three main popular types of shed base

  • Eze Base
  • Concrete Base
  • Paving Slab Base

Note:  Whichever method is more suitable for you, we recommend that you have a 2-inch (5 cm) lip around the base of your shed. To calculate the size of base required for the particular building you wish to build, add 4 inches to the overall base dimensions to ensure an adequate base size for your shed.

How to Build an Eze Shed Base

Many garden sheds come with the option to purchase an Eze base. This is the easiest and quickest option, make sure the ground you are laying your base on is flat and level. It is recommended to lay your Eze base on top of a concrete or paved surface. Watch the video guide below:

How to Build a Concrete Shed Base

Equipment Checklist

  • Pegs and string
  • Building sand
  • Standard cement (all-in ballast, cement & water)
  • Timber for base formwork
  • Tape measure
  • Spade
  • Sweeping brush

1: Mark out your base

Decide where to position your garden shed, allow enough distance from hedges, garden gates and watch out for the garden fence panel for easy access to all sides. Using the pegs and string, mark out the base 2 inches (5 cm) larger than the area of the building on each side. Finally, measure diagonally across both sides to ensure the area is square.


2: Level Off the area

A concrete requires 3 inches (7.5 cm) of compacted hardcore (all-in ballast or other crushed rubble/gravel) underneath the 3-inch concrete layer. The base can be level with the ground or raised above it. If you want it to be level, excavate the top earth to 6 inches (15 cm), to allow for the hardcore layer and 3 inches (7.5 cm) of concrete. Level the area with a rake and spade and remove the pegs.

3: Create a Levelled Hardcore2

Set up a levelled formwork. This involves measuring, cutting and fitting timber to the shape of the base in order to contain the concrete. Check diagonal measurements to ensure the formwork is square and level, as this will determine whether your shed base is 100% sturdy. Next, spread a layer of well-compacted hardcore (all-in ballast or crushed gravel) and cover with a liberal amount of sand. This needs be well compacted and flattened down, preferably with a compacting tool or roller.

4: Add the Concrete

Mix concrete using one part cement to five parts all-in-one ballast, or use bags of dry-mixed concrete and just add water.

Remember small amounts of water should be added at a time and mixed into the concrete. Be careful as excessive amounts may make the cement too sloppy and it needs to stay reasonably dry. Spread the concrete evenly and slightly above the formwork. This can be then levelled off with a long straight edge of timber resting on the formwork using a sawing motion slowly (as shown below) over the entire surface of the freshly laid concrete.

If wet weather is forecast, cover the concrete with polythene for 24-hours. In warm weather, cover the base with damp sacks and sprinkle them with water over the 24-hour period, this will ensure the drying concrete will not shrink and crack. The result is a smooth, sound, level base. The perfect foundation for the construction of a garden shed.

How to Build a Slab Shed Base

Equipment Checklist

  • Pegs and string
  • Flat Face Paving Slabs
  • Building sand
  • Standard cement (All-in Ballast, cement & water)
  • Rake
  • Tape measure
  • Spade
  • Rubber mallet
  • Sweeping brush

1: Mark our your base4

Decide where you will be placing your garden shed, leaving enough space from hedges, fences and boarder for easy access to all sides.
Using pegs and string, mark out the base 2 inch (5 cm) larger than the area of the building on each side. Finally, test the size by measuring the two diagonals to ensure the area is square. Some metal sheds come with foundation kits that increase the footprint of the building – ensure that,

2: Dig, level off and rake the area

Strip the topsoil and dig out to a depth of approx. 2.5 inch (7 cm) to accommodate the base. Level the area with a rake and remove the pegs.

3: Mix the cement

Mix together one part cement to eight parts building sand for a dry sand and cement mix. Spread this evenly, ensuring that the mix sits approx. 4 cm in depth. Ensure that it is level.


4: Lay the paving slabs6

Starting from one corner and working outward, lay the slabs by tapping down on the centre of each slab with a rubber mallet. Using a spirit level, ensure all the slabs are square, level and firmly butted together for a solid base.


5: Double check the base is level and flat

The completed base should now be level and square. Conduct a final check with a long straight edge piece of timber to check if the base is level from each corner and also measure the diagonals to finally check that the base is square. Brush off any excess dry sand/cement mix, which could hinder the levelling of the shed. The result is a smooth, solid and level base.

Frequently Asked Questions

Will I need help to build my base?

Constructing the foundation for your garden shed is a fairly hassle-free task for a single person to complete. When it comes to actually assembling the shed, we do recommend an extra person is on hand one the panel constructed for lifting and placing roof and wall panels in place.

Do I need planning permission for my shed?

Planning permission is not normally required for construction of a garden building, unless you live in a conservation area or the building could intrude on a neighbour’s garden. You may wish to check with neighbours or local council before construction.


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