Like your house, a wooden storage shed must sit on a foundation. Of the two most common types of foundations, that being the concrete slab and the wooden skid foundation, the slab is somewhat more elaborate. The concrete slab foundation for shed is also known as a slab-on-grade foundation. The slab foundation will be discussed in this article.
The concrete slab, when used as the floor of a storage shed, will be 3 ½ to 4 ½ inches thick with a perimeter or footing of 8 to 12 inches thick. The depth of slab, the type of metal reinforcement, the amount and type of gravel used for the sub-base and also the type of moisture barrier used can vary depending on local building codes. Generally the entire slab foundation can be poured all at one time using a wood form. When used in cold weather climates slab-on-grade foundations can only be used for detached sheds. The foundation, because it sits above ground is susceptible to frost heave in cold weather. If the building was attached the frost heave could cause damage to the attached building.
The concrete floor slab of the shed requires quite a bit of concrete so it is beneficial to have it delivered by cement truck to the backyard work site by a local ready-mix company. Most ready-mix companies have a one yard limit before they will deliver. Air-entrained concrete wears best for an exterior slab and the ready-mix company will mix it for you if you inform them of how it is being used. If you are pouring a smaller slab you can rent a concrete trailer from a rental store or landscaping company. The concrete trailer is towed by car or truck with one yard of cement already mixed and you pour it yourself.
Finishing a large slab can be quite tricky if you have not worked with concrete before so you may require some assistance with the pour.
The required tools for laying a concrete slab foundation are:
- Circular Saw
- Mason Line
- Sledge Hammer
- Line Level
- Framing Square
- Rented Plate Compactor
- Bolt Cutters
- Bull Float
- Hand Held Concrete Float
- Concrete Edger