18 are capable of spanning across non-load bearing areas, and are commonly supported by soil or pilings. Grade beam footings differ from continuous spread footings in how they distribute loads. The depth of a grade beam footing is designed to dis- tribute loads to bearing points, while the width of a continuous spread footing is designed to transfer loads to the ground. (Source: all-about-foundation-repair.blogspot.ca) A slab is another common type of shallow foundation common with greenhouse structures. The slab will be about 4–6 inches in thickness, except at the perimeter where it will be thickened. All concrete foundations should include the use of rebar to strengthen the concrete as well as steel mesh in the slab options. In terms of overall depth, the foundation should be planned as you would design a typical outbuilding. It is critical to ensure the concrete foundation is built according to your local climate given that our typical 8x12 glass greenhouse is close to 1200 pounds. The concrete must cure and be level and square for easy installation.