A shed base is an essential part of building a shed. it needs to be properly made in order to give your shed a solid foundation. on the face of things, building a shed base might seem like a daunting task, but follow these simple steps and you�ll have a level and sturdy base for your new shed in no time at all.. How to build a shed base advice on laying timber, plastic, paved and concrete bases a firm, level base should be the starting point for any shed or garden building.. How to build a garden shed base build your own steel shed 10x10 shed instruction manual arrow how much is a shed livable sheds designs when you finish then draw another triangle which will be smaller in proportion. this would go inside the triangular section of plywood..