Just like any other building, a garden shed needs to be built on a firm set of foundations, especially if it’s a larger shed. The best material to use is concrete, but because this can be expensive and difficult to put in place, it may not be suitable for your particular project. However, if you are planning a larger structure or one that you hope will pass the test of time, then this is definitely worth the extra investment. The concrete slab needs to be about 100mm thick and, of course, for larger structures a more substantial base will be required.
With most wooden shed kits you will usually get some kind of wooden flooring included. This normally takes the form of tongue and groove boards laid on battens which help raise the floor from the ground and prevent it suffering from the effects of damp and mould. These battens also enable airflow under the structure which also helps prevent the floor from rotting. Of course, these battens should ideally be placed on a concrete foundation to prevent them from rotting themselves, but if a concrete base is not possible then make sure they are treated and preferably laid on a membrane or even a bed of stone chips.
One of the best, and most cost effective bases for your wooden storage shed is actually paving slabs as these are cheap to buy and easy to lay – just ensure that the soil is levelled before putting them down.
Here are the basic steps involved in marking out and laying the base for your shed.
Use tape or string and pegs to mark out the base of the shed – remember to add a surround – usually 50-100mm on each side. Remove the turf if there is any, and flatten out the soil as much as possible. If you need extra help, hire a rotovator to churn up compacted soil and then skim off the top level until its flat with a normal garden spade.
Using a spirit level lay the slabs in a regular pattern along one edge. I recommend that you use a hardcore base if possible as this will help drainage and give a smoother base to work from, although soil will be fine if levelled correctly.
If possible, cut a slab in half and continue the next line by placing the half cut slab down first. This gives a staggered pattern which helps dissipate the load and avoids having lines of slabs rising up along their edges in the even of uneven weight distribution in the shed.
Continue until you have filled the area. Don’t make any longitudinal cuts of the slabs unless absolutely necessary, this is a lot of extra work –just make the base the width of the slabs.
Finally, place the battens across the slabs making sure they are central and coat them with a good quality wood preservative. Similarly, give the underside of the base a couple of coats as well since you wont be seeing this again for a long time – at least that is the plan!
That’s it. Your base is ready and its time to move onto the next part of the project – actually putting the shed together. Making the base might not be the most exciting part of the project but it is one of the most important – get it right and the rest of the jigsaw will fall easily into place.