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Shed Base

A shed base is an essential part of building a shed, the base needs to be properly made to give the shed a solid foundation. Never assemble a building on an unsound base, otherwise you risk the panels and roof not lining up and doors becoming unaligned. Building a base might seem a daunting task but follow these simple steps and you’ll have a level and sturdy base for the new shed in no time at all.

Please note; neither of these bases should be used for a garage base. We will send different requirements for these.

Plan where your shed will be located

  1. Make sure there’s access for carrying panels to the site and for maintenance.

  2. Foliage and trees that may grow in the future

  3. Natural light for workshops for example

  4. View of the garden for the planned area for a summerhouse

  5. Consider the roof overhanging more than the building measurements

  6. Consider whether you intend to run an electrical supply to your building

Choosing the type of base

There are 4 main options:

  1. Concrete shed base

  2. Slab base

  3. Timber shed base

  4. EcoBase fastfit

For large buildings, a full concrete base is your best option.

Whichever method is more suitable for you, we recommend that you have a 2” lip around the base of the shed. To calculate the size, add 4” to the overall base dimensions to ensure an adequate base size.

Please note: Garage bases are somewhat different to a shed base, if you require a garage base then please contact us for the best option to suit our garages.

How to build a concrete base

Equipment checklist

  1. Pegs and string

  2. Building sand

  3. Standard cement

  4. Timber for shuttering work

  5. Tape measure

  6. Spade

  7. Sweeping brush

  8. Rake


  • Mark out your base

Decide where to position your shed with enough clearance for easy access to treat and allowance for roof overhang. Mark out the area using the string and pegs as large as you want but no less than 1” smaller than the footprint of the shed on each side. Finally test the size by measuring the two diagonals are the same to ensure the area is square.


  • Level off the area

A concrete base requires 3” of hardcore, all-in ballast or other crushed rubble/gravel underneath a 3” layer of concrete. 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”, to allow for 3” hardcore and 3” concrete. Level the area with the spade and rake then remove the pegs and string.


  • Create a levelled hardcore

Measure, cut and fit timber to the shape of the base which will contain the concrete, framework/shuttering. (Please note concrete can push out the sides of the framework/shuttering, therefore it is advisable to put strong pegs at the sides to stop this from happening) Check diagonal measurements to ensure the framework/shuttering is square and level, as this will determine whether your base is 100% sturdy. Next spread a layer of well compacted hardcore and cover with liberal amount of sand. This needs to be well flatten down, preferably with a compacting tool or roller.


  • Add the concrete

Mix the concrete using one part cement to five parts all in ballast, or use dry mixed concrete and add water as per the instructions. Remember small amounts of water should be added at a time and mixed into the concrete. Be careful as excessive amounts may make the concrete too sloppy and it needs to stay reasonably dry. Spread the concrete evenly and slightly above the framework/shuttering. This can then be levelled off with a long straight edge of timber resting on the framework/shuttering using a sawing motion slowly over the entire surface of the freshly laid concrete.




If wet weather is forecast, cover the concrete with a polythene sheet 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.


How to build a slab base

Equipment Checklist

  1. Pegs and string

  2. Flat face paving slabs

  3. Building sand

  4. Standard cement

  5. Rake

  6. Tape measure

  7. Spade

  8. Rubber mallet

  9. Sweeping brush

  10. Spirit level


  • Mark the base

Decide where you will be placing you shed, leaving enough space on all sides to treat and for the roof overhang. Using pegs and string, mark out the area as large as you want but no less than 1” smaller than the footprint of the shed size on each area. Finally test the size by measuring the two diagonals  are the same to ensure the area is square.


  • Dig, level off and rake the area

Strip the topsoil and dig out to approx. 2.5” to accommodate the base. Level the area with a rake and remove the pegs.


  • 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 is level.

  • Lay the slabs

Start from one corner and work outwards, lay the slabs by tapping down on the center of each slab with the rubber mallet. Using a spirit level, ensure all slabs are square, level and firmly butted together.

  • Double check the base is level and flat

The 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 corner to corner and measure the diagonals to finally check the base is square. Brush off any excess dry sand/cement mix, which could hinder the levelling of the shed.

Timber shed base

Pressure treated timber and galavaised spikes suitable for sheds upto 10 x 8, to raise your garden building off of the ground or for a level base for uneven ground without the digging. Alternatively can be used without spikes if going onto uneven hard ground for eg; old concrete or slabs










How to lay the EcoBase fastfit

Follow the link to see a video on and other relevant information.

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