It is essential that your building is positioned on a flat, solid and stable base, in order to bear the substantial weight and allow doors and windows to hang correctly and open smoothly.
The base should always be the same size as the footprint of the building, making a base larger than your building is not recommended, this increases the risk of water ingress.
Type of concrete needed
C20/Gen 3 or C25 are the most suitable types of ready mixed concrete for sheds, log cabins and garden offices. Higher strength concrete and reinforcement may be required for larger structures and therefore mix strengths should always be checked with your builder or building supplier.
How to measure a concrete base
1. Location – Consider shade vs natural light. For a potting shed, you’ll want a shaded area, whereas a greenhouse obviously needs natural light and sunshine. Take time to consider proximity to mains for power supply, or the need to get a qualified electrician to install and RCD (Residual Current Device) from the main panel box. Leave a one-metre gap between your shed and any surrounding walls or fencing, being careful of overhanging branches.
2. Measure your base – accurately measure and mark out the dimensions of your base. Check your dimensions are even by measuring diagonally; if they are the same, then the sides are equal.
3. Level the site – either dig down to firm subsoil or put a layer of hardcore down and leave enough depth for the concrete to go on top.. About half of the depth of your base should be above ground level.
4. Create a timber frame to contain the concrete. Use a spirit level to check the frame sits level on top of the hardcore and make any necessary adjustments. Place wooden pegs inside the frame and regular intervals to hold it in place. Sit pegs below the top level of the frame to make it easy to level off the concrete.
How much concrete needed for a base
Estimating concrete quantities can be a difficult, frustrating and often expensive task. You can use our concrete calculator to calculate how much you think you will need and we will arrive on-site and mix the exact requirements for the job.
For bases that are difficult to access, such as at the bottom of your garden and for large concrete pours where the use of wheel barrows will be very time consuming, we would recommend using one of our concrete pumps, which will pump the concrete from the concrete lorry to the pour area saving you on time, labour and hard work! Call us for a quote