How To Prepare A Concrete Sub-Base For Your Garden Shed

23rd October 2020

Concrete shed bases cannot be laid straight onto soft ground so you need to prepare a sub-base and frame beforehand. Our concrete experts take you through the steps to creating the perfect sub-base for your concrete and shed. 

Before you begin 

Before you start preparing the sub-base for your shed, there are a few things you need to consider, including: 

Will you need planning permission?

You won’t usually need planning permission to put up a shed as they’re typically classed as temporary structures. However, if you live in a conservation area, you may need to double check with your local council. 

Do you have enough access?

You’ll need to be able to access every side of your shed in order to paint, stain or varnish it to your desired finish and carry out maintenance and repair tasks. So, make sure you’re able to walk around the entire base and that it’s not too close to a wall or fencing. 

Would you like electricity? 

If you would like to have an electricity supply to your shed, you will need to consult a qualified electrician before starting any work on your sub-base. 

Building a concrete sub-base

To keep it fixed firmly in place, a concrete shed base needs the support of a sub-base which is made from compacted hardcore (mixed rubble such as broken bricks, blocks and stone), topped with a layer of sharp sand or ballast and finally, the concrete. 

To build a concrete sub base: 

Step 1 – Measure out where you want the shed base to go and mark the area using pegs and string. We recommend making your concrete base the same size as the base of your shed or 25mm smaller on all sides to help prevent water accumulating around the floor. 

Step 2 – Remove the grass from the area you have marked out. To do this, use an edger to cut straight lines into the grass and then use a spade to lift the turf into strips that can be rolled up and removed neatly. 

Step 3 – Excavate the area to a depth of around 15cm and use marker pegs, spaced approximately 1 metre apart, to mark how high you need to fill the hole with the hardcore. 

Step 4 – Fill the hole with enough hardcore to just cover the markers you placed around the edges of the area in the previous step. 

Step 5 – Compact the hardcore down using an earth rammer or vibrating plate and cover the surface with a thin layer of sharp sand or ballast. Give it a rake over to ensure it’s level. 

Step 6 – Build a wooden frame by carefully measuring out the sides of the base, cutting the timbers to the correct size and nailing them together. 

Step 6 – Now your base is ready to pour on the concrete. We recommend using ready mix concrete from a trusted supplier as this will ensure your concrete is the right consistency and helps to eliminate waste. 

Order your concrete today

The LGW Group brings together the South’s leading construction experts, including ready mix concrete specialists who will deliver the perfect concrete for your shed base directly to your garden. To find out more, get in touch today on 0117 958 2090.