My previous post talked about the first shop floor i did. Job relocation gave me the chance to do it all again last year( 2010). So what did I do different?
1) i used shorter sleepers, 2x4 vs 4x4(wet PT 4x4's are heavy!). My dreams of running large vac lines under the floor was never really was that practical, but electrical was handy. I left 8-12" gaps between the ends of the sleepers, so i could run cords across the sleepers, rather than just parallel to them. I also left 4"-6" along the walls so I could tuck cords under them. The 3/4 T+G is completely strong enough to span those gaps.
2) i didnt attach sleepers to the concrete. I just laid out a sheet of poly down as vapor barrier and let the weight of the floor and tools keep it in place. Every serious buyer for my last house thought the floor would be impossible or too expensive to change or remove. I basically intend to move the floor out before ever marketing this house. I can re-use the material again at the next house and get more value from buyers who prefer a concrete floor.
3) I built a flip down ramp to get cars/tools/materials in. I almost never give up shop space for cars, but a ramp makes it much less dicey. If I was parking in there regularly, i'd have build the ramp in permanently, but i didnt want tools sliding toward the flimsy garage door.
4) i used square drive screws and a cordless impact(the white makita). Its unbelievable how much easier this made the job. Wear earmuffs when using the impact....
4 1/2) dont drive the screws deeper than flush, or just under flush. The wheels on mobile bases can snag on the holes of overdriven screws, and under driven, or badly angled ones, stick up above the floor. If you drive them just a hair below flush, a heavy paint will basically level them out.
5) I dropped mason's line in the channels between the sleepers, before i put the plywood down....no fishing wires blind later(hopefully).
6) I also planned the staggering pattern of the plywood so the smaller cut sheets ended up under the breaker box, and expected outlet placements. On these cut sheets, I cut the bottom of the tongue off on these short edge sheets, so i don't have to cut holes in my pretty new floor to take out a section to run wires. In the last garage, I started the staggering at the breaker box, so the interlocking tongues prevented unscrewing the first sheet with out taking out all the ones in front of it. I only shaved the tongue on small edge sheets, so the the floor stays flat in the middle where tools roll often.
7) after being told not to put rustoleum epoxy on wood several times, I did it anyway. Still content with it. I bought a bunch of extra flakes to get more traction. But i made the mistake of applying the epoxy only a balmy Houston day where the low temp for the day was 82 degrees. We waited till midnight to apply it in lower temps, but it was still too hot. The epoxy cure time drops to like 15 minutes....plus i left the cans in the car, so it was even warmer than ambient. We waited too long to spread the flakes, which don't stick well to dried epoxy. I ended up with a couple inches of flakes in the shop vac the first time i swept, which is a waste of expensive flakes.
8) Made spike shoes for walking on wet epoxy floor with out leaving foot prints. Just traced me and wife's shoes on plywood, cut em out wit the jigsaw, then ran a few dozen brads through each piece and strapped them on my shoes with cable ties, or velcro cable wraps for wife's smaller feet. Unfortunately, not too useful, since epoxy was drying on the rollers.
9) i did 24" centers on the sleepers, except where the car tires normally go. 16" centers was over kill, and honestly, was almost too stiff. i wanted more flex in the floor not less. My jointer weighs about 850 lbs and rolls across the floor quite well.
I've only lived with this floor for a few months, and haven't spent enough time out there yet. About the only thing I'd try different at this point is to put the epoxy in the fridge a few hours before using it. The working time can almost be trippled vs hot weather. The plywood soaks up more epoxy than concrete, and shows a lot of grain. So i'd probably plan do a second coat next time. the moving schedule and weather didnt cooperate this time, so one coat is all it got.
Hope this helps!
Don