I mounted my 25-gal, Craftsman prof. 2-stage compressor up on the "knee wall" in my garage/shop. I have the advantage of a half vaulted ceiling in there and I noticed one day the the compressor looked like it could fit just about right up there!
The compressor is bolted to two pieces of laminated 3/4 ply with a hold drilled in the center for water draining ease.
I lag-bolted a chunk of oak to the massive beam spanning the garage and used water-heater earthquake strapping as a precaution along with the chain/s-hooks you see hanging from the rafters. As one final precaution, I have some steel cable attached the handle of the compressor and hooked around a metal hook screwed into the wall.
Next I need electrical up there and an air-hose reel. So far, so good with the compressor up there. I have plans some day to bring down and replumb the air regulator and on/off switch but so far, the compressor hasn't decided to kick-on at 3 am. The hose reel attachment above my head has been a godsend...it is centrally loacated within my garage is just as easy to reach as it is to shuffle out of the way!
I realize some of you may not think it wise to have something like this overhead but I feel very safe with what I've done to secure this thing...my DP is right under it! As we all know, floor space is such a valuable commodity in a 2-car garage... Thanks for looking...fire away with question and comments!