three seasons room

I am interested in building a three seasons room behind my garage. It would be 10 ft. x 14ft. It would be attached to the garage with the peak running perpendicular to the garage. The foundation has to extend at least 40 inches below grade and 8 inches above grade. The roof support can be made of trusses. There is currently a cement slab that covers part of the area on which I wish to build. I plan to hire someone to demolish the existing slab and someone else to pour the foundation and cement floor. I plan to do the building myself. There is nothing else in the way of the building area and it will not come close to the property lines so setback restrictions will not be an issue.