I have a few questions about a project I'm planning on doing for a friend. He wants a 16 x 23 slab done out of his backdoor of his garage. In that 16 x 23(4") area will be a 10 x 10 area poured at 6" b/c he plans to put his hot-tub there. I plan on doing the digging and forming and getting another friend to do the pour/finish. He does this for a living and has 15 yrs experience. The slab will up to the foundation with a gap. He was quoted, 2200.00 and 1600.00 from another person he knows, but can't do it for 4 weeks. I planning on 1600.00. It is 6.5 yds and 800.00 for the concrete. Any advice or input will be helpful since this is my first slab. Done a few paver jobs.