What sort of base do I need for my garden shed?

This is one of the questions we are asked about the most in relation to sheds!

Firstly, we would recommend that you purchase a shed with a built-in base supplied on pressure treated floor bearers. This then needs to sit on a level surface. Pressure treated timber protects the wood from rot and insects, but not from prolonged moisture. So, it is important that it sits on a surface that will allow air to flow freely below the shed.

If your shed location is particularly damp, such as under trees, or the soil is heavy and prone to waterlogging, consider swapping the timber bearers for recycled plastic floor bearers to ensure a long life for your shed.

Grass or soil is unsuitable for a base as it can become waterlogged, causing rot or sinkage. Even though you won’t see your shed’s base after installation, having a level prepared solid base is essential to ensure the longevity of your shed.

Let’s discuss some of the materials available for a shed base:

Type 1 (a mix used as a foundation made up of crushed stone) or stones are laid within a wooden frame to hold them in (unless support is provided by surrounding walls or slabs when they can be laid without a surround.) If a wooden surround is used, this should be constructed from 100x50mm pressure treated timber to form the desired base shape. This needs to be at least the same size as the shed that will sit on it. The stones themselves need to be 100-150mm deep across the whole area. You may need to dig out some soil, so that the finished height reaches the desired level.

Lay the frame down, checking with a spirit level that it is level, then secure the shape by pegging it out. Then fill it with the stones and start levelling, ideally with a wacker plate (available to hire from outlets such as Hire Station).

Our Verdict – A very cost effective and simple way to prepare a shed base with good drainage. Can easily be done by a competent ‘DIY-er.’

Our Verdict: A very durable foundation, especially for a larger shed. However, it requires skill from the installer so is not a suitable undertaking for inexperienced DIY-ers. Concrete is a hazardous substance and ,therefore, care needs to be taken when handling it. Unless familiar with using concrete and in possession of a mixer this is a job best left for a professional.

Our Verdict: Levelling slabs can be tricky but, as with concrete, this will be a very durable base for your shed. If your base extends beyond your shed, consider guttering. This will prevent rainwater splashing off the surrounding base and up the sides and underneath your shed, which over time could cause problems.

If the slabs are just going under the shed they do need to be flat and stable but do not need to be laid on concrete or butted closely together. In this circumstance, they are simply there to keep the base of the shed off the ground. This is an easy job for a DIY-er with all materials readily available at your local DIY store.

Decking is an option that can work very well as a shed base. Building decking can be a complicated process if it is part of a larger landscaping project, however it is relatively simple for a stand-alone shed. Historically timber decking needed a lot of maintenance and was prone to rot, but the availability of pressure treated timber has alleviated this. Decking is less suitable for a large shed (especially if it is insulated) due to the weight of the structure.

Our Verdict: A good option for a small shed or store, particularly if it is already existing in the garden. Not suitable for large or heavy sheds.

Our Verdict: An easy option, quick to install with minimal tools, although can work out quite pricey.