As with your home, the foundation is key to having a structurally sound building. However, you have many more options with a shed than with a home. A lot of it depends on the size of the shed, the materials used for the shed, what your needs are for the shed and the climate you live in.
Once you have selected a good set of shed plans, the plans will give you a list of recommended shed foundations for your specific shed. You can also look for concrete Foundations through sites like http://maxraft.co.nz/.
Here are 4 different types of shed foundations typically recommended:
1 – Dirt Floor Foundation – By far the easiest and cheapest, but you are very limited in the use of a foundation like this. It is typically used for a pole type barn where you can store farm equipment, hay or even a way for farm animals to get out of the weather. Not a good option for storing those items that need to be kept in a dry place.
2 – Crushed Gravel and/or Cinder Block – This is also a very easy and inexpensive option for shed foundations. If you are not concerned about water drainage, you can simply have about 6" of crushed gravel brought in and put on your pre-leveled ground and then place your shed on top. For just a few bucks more you can elevate your shed even more by adding Cinder Blocks on top of the crushed gravel.
3 – Concrete Slab – This is the most expensive of the shed foundations but the most stable and dry option. Most do it yourselfers prefer to have a professional pour their slab, which adds to the cost.
However, depending on the size of the slab, it could be something you can do yourself and save some money. Keep in mind that concrete absorbs moisture so whatever frame parts of your shed that come in direct contact with your concrete slab should be pressure treated wood in order to eliminate rot.