Typical construction of the patio area always contains the following: Excavation of the site followed by construction of a small concrete foundation around the perimeter. All edging paving is cemented in creating a small wall tying the patio together. Depending on size of patio area and soil type, typically 6-10 inches of hardcore is placed on a membrane. All paving is then cemented in and pointed, depending on paving selected. Drainage pit is required depending on patio size and location.