I've been following this thread closely as I want to add wifi to my shop as well. Apparently I'm a total novice because I'm constantly googling things from the thread that I have no idea what they mean... LAN, AP, Bridge, ubiquiti, cat5, etc etc.
I read many comments that users are getting wifi to their 'garages' no problem. I consider 'shops' and 'garages' quite different. A detached 'garage' being stick built, with siding of some sort, and a shingle roof. Where as a 'shop' being a pole building, steel sides with steel roof.
Am I correct in that I need to pursue wifi differently for a steel sided, steel roofed shop, because the signal won't penetrate those barriers. However on a detached garage (non-steel building) the signal will. Therefore depending on the structure I should approach adding wifi differently. (Note - In a case that running a buried cat5 or cat6 cable, which appears to be the best method based on posts above, is not possible).