Can anyone offer any indication of what a reasonable price would be to have a builder come and lay a suitable concrete base? according to the shed manufacturers' instructions, the minimum base. Prices of storage shed how to make a concrete base for a tool shed ashes by now free 6 x 16 lean to shed plans build a shed for less than 1000 # spend time to measure every of your woodworking display. appropriate measures are integral on the success of one's woodworking undertaking.develop a system to hold your plans for cabinetry.. Preparing timber formwork for concrete. now we have a base area ready. it should, in all cases, be 300mm longer and wider than your shed floor and as level as possible. using the diagram below follow the instructions for an above ground base. dimensions and layout for a shed base.