I'am having a Deck build on my raised home in New Orleans. My back yard has a very thick layers of concret that seems to have been placed in layers(to expensive to remove). My deck contractor has given me the option of having the foundation of my Deck build on the existing concret with or busting through the cement to dig foundation holes. What is best? If he digs the holes who deep should he dig? Please help need answer today. Deck is 14X20. Thanks so much!J