Jeffvette

Jerry, I would add one more section to the garage. If you plan on cleaning, media blasting or grinding at all, it's best to have a seperate enclosed room to help contain all the debris that scatters and keep everything else clean.

I would also second a floor drain for winter or inlimate weather cleaning. We had one when we lived in Anchcorage and it made things so much easier. Especially whe nthe snow was melting.

As far as the floor, nothing is impervious. It just matters how long it lasts before it cracks/peels/chips/fades.