Step 1:
Decide where to position the shed in an optimal space, allow enough distance from hedges or fences for easy access to all sides. Using pegs and string to mark out the base 2 inch (5 cm) larger than the area of the building on each side. Finally, measure diagonals to ensure the area is square.











Step 2:
A concrete base requires 3 inch (7.5 cm) of compacted hardcore underneath the 3 inch (7.5 cm) concrete layer. The base can be level with the ground or raised above it. If it is to be level excavate the top earth to 6 inch (15 cm) to allow for the hardcore layer and 3 inch (7.5 cm) thickness of concrete.

Step 3:
Set up levelled formwork. This involves measuring, cutting and fitting timber, to the shape of the base in order to contain the concrete (as shown in the diagram). Check diagonals to ensure the formwork is square. And also ensure the formwork is level, as this will determine whethery your base is 100% level.Next, spread a layer of well compacted hardcore and cover with a liberal amount of sand.

Step 4:
Next, mix concrete using one part cement to five parts ballast or use bags of dry-mixed concrete to which you just add water. Small amounts of water should be added at a time and mixed into the concrete mix to ensure excessive amounts are not added making the cement sloppy, as the concrete should be kept on the dry side. Spread the concrete evenly and slightly proud of the formwork. This can be then levelled off with a long straight edge of timber resting on the formwork using a sawing motion slowly (as shown below) over the entire surface of the freshly laid concrete. If wet weather is forecast, cover the concrete with polythene for 24-hours. In warm weather cover the base with damp sacks and sprinkle them with water over the 24-hour period, this will ensure the drying concrete will not shrink and crack. The result is a smooth, sound, level base. The perfect foundation for the construction of a garden building.