We think foundations are a very important part of your new shed. why are foundations so important? the foundation supports the walls, and the walls support the roof of the shed. and the supported roof is why you are building a shed in the first place! this makes choosing the right foundation important.. A shed foundation of gravel is good for a small to medium shed. it is a sturdy foundation and can withstand heavy loads if you are putting equipment in your shed, but they are not the best for large sheds. a large shed that holds equipment should be on a concrete slab. dig a hole the size of the shed and then put the gravel in the hole.. Building a concrete shed foundation can be done easily but it takes some time to do it right. make sure you find the right place and get the proper permits for your shed. prepare the ground for your shed by digging the foundation to the proper depth. build the shed foundation framework and make sure it is level and squared off properly..