I am stuck with a narrow slab 24' long and 14' wide not able to expand it because it is grandfathered in and I live at the beach so concrete is very hard to get approved.
My slab was just thick enough for the 2 post lift but not strong enough from a lack of rebar in the right spots. I cut a 5' wide tapered trench 4' deep because half a load of concrete was the least I could buy and get delivered, please check with your supplier to see what restrictions you will have. So I figured out I could make the trench deeper and more flared out as we went down and drilled rebar into the slab and filled the trench up with more rebar and used long "J" hooks attached around the rebar instead of expansion bolts to hold the 2 post lift in place, this is MUCH safer and stronger than the expansion bolt down type. The trench came in at 25,000 pounds so that is a stable way to hold a 10k lift because I also work on pick up trucks that are 8000 pounds. I have a tall door and a small space so the back end of the 18' trucks sticks out the door when up on the lift. When the garage was empty I pulled in different cars and trucks to get the lift posts in the right spot. I have just walking distance around the cars and used 8' LED's down the side and across the top side of the lift to give me "body shop type straight reflections off the cars for detailing. For benches I had to cantilever them off the walls so no bench legs stick out and get in the way when you are walking around.
I put in 30 windows for winter light.
The stairs are the upper level where my tool boxes go to protect them from flooding.
And yes I know the roof is not straight..I fired that contractor and redid it my way and bolted every board together and braced the crap out of it to hold up to 150 MPH winds here in ground zero for hurricanes and it does not shake or move at 100mph so far.. 130 mph rated big and tall garage doors cost a fortune.