Engineered slab on grade usually refers to garages or out building that do not require building frost walls. Meaning your slab is poured with your footings all at the same time and its structural engineering such as the amount of structural steel required or insulation requirements is designed by an engineer. Wilson Excavation Ltd. can do this all for you including the engineering, drawings, and permits required. Engineered slabs are often used because of cost or drainage solutions. They require less excavation of the site and are quicker to build.