(also see the thread http://familywoodworking.org/forums/...ead.php?t=1320 for Part 2)
My shop is located in my one car garage where I had concerns in setting it up about working on concrete all day with my fairly flat feet, un-evenness of floor, coldness of floor, and creating more storage and a place to run electrical and duct collection I went the extra mile and built it in the following manner.
My garage walls had heavily dinged drywall and I wanted to be able to affix anything anywhere so I covered them in that plywood stuff that looks like boards (can't remember what it's called, seen Norm A use it for outdoor shed walls). You need to run the belt sander over it though to soften the rough surface a bit before installing it.
First for the floor I installed a 2" by (whatever was needed) ledger and kept it half an inch away all around from the floor.
To keep away problems with condensation and allow any leaks from my sink damaging the underside of my floor, I placed a sheet of Dimplex Plastic (same stuff they place on the side of foundation walls underground) and laid on top a sheet of reflectofoil. Reflectofoil is like small bubble wrap with tin foil on both sided. For those (like myself at first) who think this reflectofoil stuff doesn't work, when I finished laying it down that minus 20 degree nite in January I was so tired I lied down on it and fell asleep only to awaken an hour later sweating because I was now overdressed for what the room had warmed up to. Both the Reflectofoil and Dimplex are tucked underneath the perimeter ledger and kept an inch or so away from the the actual side walls so as to allow your floor to breathe. (Many people, even like myself did, do not realize that concrete should be viewed as a big sponge. It's breathing all the time and any hydrostatic pressure on the other side of the concrete is slowly permeating thru it. If you slap 6 mil poly one side of it you are trapping the water from evaporating.)
The rest as the photos show are essentially two "boxes" or "modules" as I refer to them that are fastened to the floor thru the dimplex and reflectofoil with tapcon screws and are laid out to create a perimeter channel around the shop to run dust collection piping and electrical BX cable to the gazillion electrical outlets I've run from my sub-panel. The perimeter Channel is wide anough to accomodate 2 four inch PVC runs and a whack load of BX electrical.
Each of the two modules are assembled and fastened to the floor in a different manner. I wanted to avoid any visible screws on the top side as much as possible. One module, I used my pocket hole jig to fasten screws from the joists to the top plywood from the underside and then fastened the bottom base plate together and then tapconed the whole unit to the floor. You can't really see it in the photos but the joists that are the outer egde of each module over extend about 3/4 inch all around so as to be able to support a removeable cover that lays on the perimeter ledger also. So, that means all the joists are to be level with your level perimeter ledger. I cut a lot of bevelled and shimmed joists and ledgers to make my floor level on my bandsaw using a 3/4 inch blade which I must say was the trickiest and maybe most critical part to get good results overall.
Insofar as how I went about differently with the second module, I fastened the botton of the module to the floor first and them srewed the shimed joist to it and then fastened the top to the joists countersinking the screws and covering them with wooden plugs. If I ever wanted to remove all of this because I sold the house and a new owner wanted to use it for a car, this module would be a dog to remove, but the first one could come off in minutes.
Due to the concrete floor sloping from front to back and side to side by up to 5 1/2 inches over a 21 foot distance the joists required a variety of either 2 x 4's to 2X 8's.
Each module also has removable lids that I can use to store lumber in. I polied the tops of the modules and their covers (sweeping is a breeze now) and I use those glass suction cup thingies to remove them when I want to get in them. Each opening of the storage compartment is reinforced with half inch square metal bar. Not sure if this was necessary but otherwise it would have been just the 3/4 inch plywood cover and with 500lbs machines rolling overtop, I wanted to make sure they would not sag or break.