How To Make A Foundation For Your Garden Shed

A foundation is essential for any shed. It keeps the shape of the shed, and providing good anchoring points. A good elevated base will also keep the interior of the shed dry. 

Pick a site for your shed first. Try to visualize what the building will look like in the position selected. Make sure that access is going to be adequate for the intended usage. Take into account the distance from the site to the closest electricity and water points etc.

There are two options for you: a concrete slab or a timber foundation. Both options have their advantages, so it would be best if you consider what your shed is going to be used for before you make a decision. Do you plan to use the shed for garden tool storage, and fertilizer? Or you are going to store your ride on mower or ATV? The amount of weight you will put on the floor will determine which foundation option you should go with. Also are you the owner of the property or you are planning to move the shed to somewhere with you in the future.

Generally speaking, these two options will have these features:

  • Concrete slab: It will support the most weight and provide a long-term solution. However, it is more expensive and permanent. 
  • Timber foundation: Easy setup and removable. This is the option we usually suggest customers to choose, unless you have some heavy items you need to store. 
No matter which option you choose, please always make sure the surface is properly leveled. If not, Your Steemates garden shed will be difficult to be assembled, and will cause problems like the doors won't open and close properly and possibly cause leaking. All foundations should also be built above ground level, in order to avoid rainwater running inside. Here are some tips for both options. 

Option 1. Timber foundation


Steelmates offer a detailed floor plan for all the models we sell, it gives you info on timber specs, quantity, and how to put together. Feel free to contact us if you have not obtained one yet.

In general, all timber used need to be treated. The bearers on the bottom need to be H4 treated, and others H3.2 treated, which includes joists, plywood or fence paling boards. If the ground is perfectly leveled, which rarely happens unfortunately, the bearer can be laid on the ground directly, and build on top. If the ground is not leveled, do not start digging, it will take forever! Instead, all you need are concrete blocks or bricks. Dig shallow holes about 20mm to 30mm deep and fill with pebbles, these will prevent foundation subsidence. Put blocks or bricks on the pebbles. Each bearer will need 3 supports. These will raise your building off the base altogether, stopping any damp from rising and encouraging air circulation.


Option 2. Concrete slab

The foundation for your shed will be a little bigger than the shed itself, so keep this in mind when selecting your site. Refer to your Owner's Manual for your shed model for the exact dimensions for your concrete slab. You can also find those dimensions on under the "Footprint" in the Specification table of every shed. 

Make sure there is a rebate of 30mm wide 20mm deep around the footprint size, so the interior is raised to stop water running into the shed.


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