Cabinet Back Plywood Thickness

      Yet another discussion about whether to use half-inch or quarter-inch plywood for cabinet backs, and why. June 15, 2014

I'm curious how many of you use 1/2" backs for both your lowers and uppers. I've been a mixed batch over the past several years depending on the job. I think we've finally settled on going exclusively with 1/2" backs. Other than the added weight, I think there are many benefits. If you do, do you make your uppers deeper to accommodate the extra back thickness? Could some of you discuss your reasoning behind using 1/2" or not and talk about your attachment methods (grooves, dadoes, flush, screws, nails, etc).

Forum Responses
(Cabinetmaking Forum)
From contributor D:
We have used 1/2" since about 1990 for both base and uppers. Backs are inset 5/8" from wall in full dado, no nailer, however we do use a 5/8" thick hanging ledger for uppers.

From the original questioner:
Are your uppers a standard 12" deep? 12 - 1 1/8 equals 10 7/8 - is that deep enough for plates? I presume you're building frameless?

From contributor D:
Actually they are 320mm. The inside of the back is at 30mm from wall, nets 290mm or 11.42". Iíve never had a problem with dinner plates at that size and would not want to make the depth of the panels 12" to start. Parts seem to optimize just as well once you factor in the shelves and such.

From Contributor G

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Iíve been using 1/2" backs for a while now - ever since 1/4" became 5mm. No need to use stretchers because the 1/4" back isn't strong enough to put a screw in it without other support, which means you don't need to make them, install them, finish them or deal with them. All you need to do is to cut the 1/2" ply to size and install it, done. You can screw the cabinet to the wall through it and be confident that it's not going anyplace. It saved me a bunch of time. More labor savings then material savings.

From contributor B:
I use 1/2" on uppers and 1/4" on base. I build face frame cabinets. Upper cabinet sides are 11 3/4 deep with backs inset flush with back edge of side. Backs are fastened with pocket screws on all edges. Total depth of the uppers is 12 1/2". Base cabinet sides are 23" deep with 1/4" back stapled on. Total depth is 24". All finished ends have face frames with applied panels to match doors. I stopped using plywood finished ends because of the quality of plywood available these days.

From the original questioner:
To contributor B: How do you attach your base cabinets to the wall, specifically the bottom of them? Do you add a nailer inside the 1/4? This is one reason I switched to 1/2" - you can put a screw through it anywhere.

From contributor B:
I use an 8" ledger at the top of the base cabinet. This serves to fasten the cabinets to the wall and also to fasten the drawer guides too. I put two screws in each stud and don't usually have to worry about the bottom. Sometimes it is necessary to put a screw at an angle through the unfinished toe board. I use the 8" ledger also because I can rip my 1/4" plywood at 24" and get two rips out of each sheet. Then use scrap plywood as a filler behind the ledger. Over the years I have changed several times on the way that I construct the cabinet boxes. I presently use a method that I read about on this site. Iím always looking for a better way though.

From contributor V:
To contributor B: 23-1/4" boxes (24" w/ doors) would worry me, don't your appliances stick out? When you say ledger, do you mean nailer/stretcher? Are you saying your backs are 24" plus a 6-1/2" strip, with the seam hidden by the nailer?

From Contributor K

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I use 1/2" captured backs all day long.

From contributor B:
23" sides, 1/4"" backs, 3/4" face frame equals 24". Backs come up on 8" nailer about 2". I then use scrap to put along the top of nailer. Screw at top and bottom of nailer into studs to fasten to wall. It makes no sense to waste plywood behind the nailer.

From the original questioner:
To contributor K: I watched your videos and I'm very impressed with your construction methods - kudos! You may be the only one using both dadoes and confirmats! I noticed your cab backs are in a rabbit. Are you ever concerned with needing a scribe? I set mine in a groove 1/4" in from the back Ė it gives you a nice 1/4" to burn if you need it in the field. I also build to the faceframe as opposed to building the box and then attaching the frame to it. Do you ever run into issues with alignment when attaching the frames? By no means am I knocking your methods, just being inquisitive.

From Contributor K

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To the original questioner: Thanks for the nod! I plant end panels on all exposed ends - this is where I scribe. Typically the end panel (basically a door) extends 1/4" past the back, but in our current kitchen it is 1" (really bad walls). I'm using pre-finished for my boxes so I need to plant panels on my exposed ends. As far as alignment I basically flush my gables up with the inside of my faceframes (plus /minus 1/32" or so) to allow for ease of hardware installation. Alignment is a cinch. With my method it is very important to have a square back as it squares the whole box. I can't tweak it into alignment by wracking the faceframe as we are doing mostly inset cabinetry and that messes up my reveals.

From Contributor T:
To contributor K: Love your videos. I was curious which water based lacquer you're using? Do you use it over oil? Love the vacuum remote.

From Contributor K

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I use Sherwood Chemaqua Plus - sheen is job specific. Basically an oil based poly below the lacquer for a base coat, with plenty of dry time for the poly. It's really the only thing I've used that I like that brings out the color/character of the wood.

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