Heavy Backs for Upper Cabinets
Cabinetmakers briefly describe construction and wall attachment methods for cabinets using 1/2-inch. 5/8-inch, or even 3/4-inch prefinished plywood backs. November 12, 2005
Using pre-finished ply, it's not much more to upgrade the backs to 1/2 inch. So, what is the best way to build the uppers for hanging? Just screw through the 1/2 anywhere? Still use a cleat of some kind? If so, what's the best method for cleating this to the wall?
We use a 5/8 back because we build our boxes from melamine, but have used 1/2 ply with no problems. Since we always add an end panel to the last cabinet and my clients like to have a full 12" inside cabinet, we shoot with 18 gauge 2" long nails and then screw with 1 1/2" #6 zip screws. For bookcases or cabinets that need a finished end without any added panel, we cut the side of that cabinet 5/8 deeper and pocket hole the back to the side on that end. We do have a production pocket hole machine, so this goes very fast. It would be too labor intensive to do by hand. Never had a cabinet fail in 25 years with this system, and you can screw through the back anywhere without an extra strip.
My upper cabinets are made with 3/4" pre-finished maple sides and 1/2" pre-finished maple backs. The sides get a 1/4" dado all around and the back gets a 1/4" rabbet all around, making a very strong construction. Also very fast, as you use the same setup for all parts on the table saw, just moving the fence over 1/4". When you're installing, I recommend at least a 2" #8 or 10 screw. You lose the first 1" in the cab back and sheetrock, so 1-1/2" is too short. Home Depot has some pretty good screws sold in a 1 lb. box specifically for cabinet install. I build and install my cabinets so that I can hang off them. That way, I know they will last.
We use 3/4" for everything - small shop, little difference in price between 1/2" and 3/4", and I got tired of having a forest of offcut 1/2" stock that never seemed to get used. This way, we go through a unit of 3/4" PF at a time, with minimal scrap/waste. Backs get Confirmats after stapling, installed with 3" washer-head screws designed for installation. The suckers stay put!