Your shed foundation serves several important functions.
- It provides a stable base for your wood shed to sit on.
- It keeps the floor away from moisture and termites.
- And it deals with weather hazards like frost heave, flooding and wind.
On grade foundations are sufficient for most small to medium sheds.
The simplest and easiest foundation is to put a concrete block under each corner of your shed. If your shed is small, say 4×4 or 4×6, this will probably be OK. Providing that your ground is also stable.
Any thing larger and you will need either more blocks under the center of the floor or a different type of foundation that will spread the weight better.
You can build a fairly large and heavy shed on almost any type of ground or slope using a block and skid foundation. Get additional information in my FREE Shed Building Guide.
How many runners you need to use will depend on the size and shape of your shed, how the floor is built, how much weight you intend to store, and what kind of ground is under your shed.