How to build a shed base
The best houses are built on strong foundations – and that goes for sheds as well! This is my guide on how to build a shed base…
Why do you need a shed base?
It’s obvious really, but I’ll say it anyway. Get your base level and strong and your shed will be a happy one. Simply plonk your beautiful new shed on uneven, soft soil and guess what? When you try and put it up the drilled holes won’t match, the doors will never hang correctly and chances are the roof panels will be separated by a gap and will leak. Did I mention the whole thing will tilt and possibly crack any glass (if it fits in the first place that is) There – I think the message is clear.
But before anything is laid think carefully about the location of the shed. You will need to get around the structure for maintenance purposes. Avoid slamming a shed directly up against a fence or wall. Good air circulation will add years to the lifespan of a shed. Chances are you won’t need planning permission for your shed (as they are classed as temporary structures) but play safe and call your local council before doing any work.
Quickly check the soil where your shed is going. Try and push in a decent sized fence post or wooden spike. If you can then you need to consolidate the soil and add some hard-core before putting tour choice of base down. If you can’t push the post or spike in then the ground is already compacted 9 and this is good! You can start sorting your base on top of that.
Damp proof membrane is the stuff builder’s use on top of a course of brickwork to stop water from creeping up a wall. You can use it to stop water making its way up into your shed. Lay a sheet of DPM (damp proof membrane down before you set to with your concreting or slabbing skills. Remember to lay the membrane up the sides of any slabs or concrete pad (it’s only a few inches all the way round but it will prevent water causing any trouble)
The different types of shed base:
A soil layer of well-laid slabs is a great base for most sheds. Choose smooth faced slabs, as thick as you can lift and lay on a dry mix of sand and cement. Use a rubber mallet to tap down into place and allow to set hard. Moisture from the soil will move into the sand / cement mix, setting it hard within a day. Lovely! Keep the spirit level in action at all times to ensure nothing slips when your back is turned (and keep everyone from walking on the slabs until they are set hard) And don’t skimp on your measurements. Allow more base than the advertised size of shed. It will look better with a clear area of slab and accounts for any small deviation in the natural material most sheds are made from. Make sure you point the slabs (add mortar to the gaps between the slabs) to prevent any weed growth. Job done.
It may take more time than other bases but laying a pad of concrete for your shed to sit on is both satisfying and highly effective. Same rules apply really – ‘levels’ being the key. You need to create a frame to pour the concrete into – lengths of wide timber do the trick. Support these timbers, nailed or screwed to create the frame the corners, with supports on the outside edges of the frame. The poured concrete will try and force the frame apart. Mix the concrete and pour into the frame. Tamp down to remove any air pockets and then level out using a long piece of sturdy timber. Allow to set for two days before attempting to walk on it. And do wear old clothing as it is messy – but the base will look great when finished.
Perhaps the easiest way to create a base is to use bearers. Remove all vegetation and loose soil from the area where the bearers will be placed. Spread out (and level of course!) either ballast or gravel and use a rubber mallet to hammer the bearers into place. The bearers can be made from concrete or pressure treated wood – after all, they are in direct contact with the soil (gravel etc) and will rot if not the correct material. The bearers need to be paid perpendicular to the bearers that will arrive attached to the floor of your shed. The spacing between the bearers you lay is important. Space them too far apart and the floor is in danger of bowing when you walk on it. Too many bearers is a waste of cash. For example, an 8′ x 6 ‘ shed will need five evenly spaced bearers (each 6 feet long)
Top quick tips:
- Level everything – use that spirit level at all times. Assume nothing and do not rely on ‘doing it by eye’.
- Firm foundations are essential for the longevity of the base and shed – you will only lay that base once so make it a good one!
- Damp proof membrane will help protect wood from the ingress of water
- Wherever wood is in direct contact with the soil or gravel, ensure it is pressure treated for the longest guarantee against rot.
For a visual guide on how to build a wooden shed base, check out our video below: