After checking your local building codes and zoning restrictions you can decide on a location for your shed foundation (aka shed base). Foundations over wet soil will sink. Consider setting it on a place where there is good drainage, so water will not be an issue. Also, set your base away from any tree roots.
The foundation is the most important element of your shed and it is crucial that you start with one that is secured properly. Building a shed base is not complicated, and you will save money by doing it yourself. Cost will vary depending on the type of foundation you want to build.
A foundation will do several things for your outdoor wood structure. It will hold your shed’s entire load, keep moisture away from the wood and stop any undergrowth.
Most sheds can be easily set on temporary (on grade) foundations using skids or concrete blocks, which can be built easily and inexpensively. Large sheds with heavy loads may need to be on concrete slab foundations, which are permanent, last longer and are used in cold-weather regions.
This is the easiest and least expensive base that can be used to build your shed. Builders have used skids for several hundred years. Skids are treated lumber logs sometimes called runners and typical dimensions include 4×6’s, 6×6’s, or 8×8’s. To prevent wood from rotting, use treated lumber when building your base.
Skid foundations can be built quickly and are most appropriate for sites that are flat. You can place the skids on the ground but it is preferable to put them over crushed stone or gravel. The gravel will provide stability, prevent settling and will keep your wood dry.
Begin with marking your spot and remove about 4 inches of soil from the marked areas. Then, fill with gravel and compact it well using a vibrating plate or a hand tamper. Lay the runners parallel to each other on top of the leveled gravel bed. The spacing between them should be in the instructions for the shed plans you purchased to build your shed. If you ever plan to move your outbuilding you may want to do a 45-degree angle cut at the ends of the skids. Also, make a large enough hole at each end, so it is easy to insert a cable and pull them away.
Concrete Block Foundations
This type of foundation is prepared in the same manner as the one using skids. Use solid concrete blocks instead of skids and place them on even rows. Do not use typical blocks as they may not hold the shed’s weight. The size of your shed will dictate the amount of blocks required and the space that is needed among them. In order to have a square base you need to have the same distance when measuring diagonally from each corner.
Like you would do with skids, remove the sod under each of the blocks, compact the soil and add gravel. The gravel will help with drainage underneath the blocks.
Concrete Slab Foundations
A concrete base is the strongest and most durable form of a shed foundation. This type of foundation is very easy to maintain, will hold any load and also serves as the floor for your shed. However, it is also the most costly and labor-intensive.
The first step to building a concrete foundation is to take out the topsoil. Mark the area of your base and make it a few inches wider than the shed.
Prepare the forms and use wire mesh to fortify the concrete. This will prevent it from cracking after you begin pouring into the forms. The concrete should be poured from the outside to the center. Use a screed board to get rid of the excess and then a bull float to level the fresh concrete. When it is finished you can cover it with polythene material so it keeps its moisture. Allow the concrete to cure for 7 to 10 days. Then you can proceed to remove the forms and allow it to harden completely. Once this is done, your shed base is ready and you can begin construction on the rest of the shed.