Laying a Concrete Pad
As with all buildings, a shed needs a firm and level base if it is to remain sound, serviceable and safe. Without it, the shed will quickly deteriorate: the walls and roof will sag and the doors (and windows) will jam. The lower timbers in the walls will remain wet while the floor will rot because it is in contact with the ground. Not only will your shed smell, but also tools or materials stored in it will rust and get mouldy. Make sure that your shed will have adequate access because once you have laid the base it is very difficult to change the site. If a shed base is too big, rainwater will form puddles at the edges then seep under the wall, wetting and rotting the structure. If slabs are used to make a base, these must be spaced to suit
the floor size and must be laid on a firm sub-base and then bedded onto a sand and cement mix. The slabs must be level across the whole site. The best solution is to make a solid base, firm and level and the right size to suit the floor. To get the exact size of the shed floor, deduct 20mm (3/4in) from the length and width and use these dimensions to set out the floor. Select the location of the shed and mark out the base using nails and string. Then mark 150mm (6in) all round outside this area for the overall size of the 'dig'. Clear all vegetation and remove the topsoil to the required depth: for a garden shed, a base thickness of 73mm (3in) is enough, but on soft clay soils, a 100mm (4in) concrete base laid onto a 50mm (2in) well-compacted hardcore base is essential.
