My client has a raised concrete patio that he wants extended by 3 feet on each side. The patio is raised approx. 4 foot from the ground at it highest location and sits on croncete blocks with brick facing. They also want to eventually cover the patio with a structure attached to the house with posts at the far end which would rest on the new extension. This is my first attempt at a job like this. I know I will need to pour new footers and build with concrete block and backfill with rock to support the new slab extension. My question is how deep should the footers be below ground? Do I follow the freeze depth recommendation for my area which is 30"?