Sorry..got sidetracked with other household projects. Details: the floor is below grade, and the house is built in to a slope (back side of the garage floor is ~6' under the surface, at the front it's more like one foot. The garage has gutters which have their own underground drainage system (can't tell you where they drain to unfortunately).
So now I'm getting back on this little issue. I consulted an excavator (friend of a colleague), who quoted me $6000 to dig out french drains and spray some sort of rubbery sealant on the foundation. That's waaay way out of my budget right now, but he insisted that's the only sure way to take care of it.
This past weekend I decided to dig out a section myself at the front of the garage. I started by the front gutter drain pipe and took it down to the footer where the gutter drain pipe was sitting. The soil was, to my surprise, quite dry until I got down to the footer. It has been raining a bit lately, and it also rained quite a bit that night and to my surprise there was no water accumulation at all in the hole the next day. This has me wondering just how much good the French drain would do, and if my issue might be more along the lines of lacking a vapor barrier and moisture is just wicking up to the surface.
Now all that said, I'm noticing with all the moisture on the surface, it should be no surprise that it is quite humid in the garage...where I have all my metal tools and toys. Not good. I was thinking for a semi-inexpensive band-aid approach would be to put down poly sheeting, and then some sort of tile like Race Deck so the surface is durable. Again, this would be temporary, and I know it's not a real fix..but there are a number of advantages I can think of (such as, the nice floor being removable/reusable/resaleable unlike any sort of epoxy/sealant which may or may not work and cost almost as much, etc). What would be the negatives to doing this? Would it damage the concrete structurally somehow?