Step Four: Prepare the Ground and Position the Framework
Now that you have marked the area where the concrete slab for your garden shed will go, you need to dig it to accommodate the required depth and dimensions. Dig out the marked area so that the top of the slab will be at the right height. In most cases, this means that you need to dig deep enough so that the concrete is flush with ground level. Remove any roots or other obstructions. Level and compact the subsoil to reduce the risk of settling and slippage. At this point, you will be able to position the framework. Double-check to make sure that it is absolutely level. Hammer in one timber peg per metre. Saw them off so that they are level and do not protrude.
Step Five: Pour and Level the Concrete
For the purposes of a concrete slab for a garden shed, you do not need to worry about using reinforcing mesh. Prior to pouring the wet concrete, make sure that everything is ready. Have the following tools on hand: a concrete finishing trowel, a shovel, a straight screed or a straight piece of timber and an edging tool. Pour the concrete from one end of the prepared area. Level it out roughly as you go with a shovel. Tamp it well into the corners to avoid missing any spots. When the entire framework is filled, have another person help you pull the screed over the freshly poured concrete from one end to the other. Repeat the process a few times to produce a true, level surface. It should be flat, but it will also be watery.