All this talk about drains ... you could dig a moat around the shop BUT where does the water go ??? You have to get the water AWAY from the shop, not just keep it out of the shop.
You are correct sir.
I was referring to the OP's decription
he also sloped the driveway directly towards the garage and the entire floor is lower than the driveway.
A neighbor built a new house 10 or so year back and did the exact thing described above except for the floor being lower part. He ran a 6" wide cast iron/steel grate the entire width with a large 8"? pipe under it and has had zero issues.
If the surrounding are is below the floor (his was). The OP's sounds like it may not be? If not, one might be able to use a sump pump or similar devise. Just trying to come up with cost effective solutions for the OP.
Years ago when I bought my property. the previous dipsh-t put up a 30x48 metal building 300ft downhill (fairly steep grade) from the house. Well he tried a shallow drainage ditch to direct the water away. That wasn't working to well by the time I bought the house 5 years later. OK, so I noted inside, at the bottom of the walls there was pressure treated wood about the height of the outside dirt? A little work with a shovel revealed MR. DS had covered the pressure treated wood with what appeared to be roofing tar paper that was disintegrating. [censored] was this guy thinking?
So we had the area regraded to just below the wall creating a drainage ditch alongside and out back of the building a ways. Added matching metal siding slipped under the existing side. Back filled with a little dirt to just cover the bottom of the siding and so far, no more water
