Plywood Thickness for Cabinet Cases

      Is 5/8-inch plywood okay? Half-inch, even? Cabinetmakers discuss the pros and cons. December 14, 2005

Question
In 24 years of cabinet and furniture making I have never used 5/8" sheet material for anything except stacker sheets. I have always used 3/4" sheet goods and I have never even considered anything else until now. My vendor is currently out of their usual 3/4" A1 cherry ply and he offered me a significant discount for some 5/8" he has in stock. My knee-jerk reaction was no, but then I started thinking - why not? I'm not interested in whether or not it conforms to some arbitrary industry standard - I'm wondering what the pros and cons might be.

Forum Responses
(Cabinetmaking Forum)
From contributor A:
If you make face frame style and you nail the face you will have to be more accurate to avoid shiners. The use of 5/8" for shelves might be different visually and not quite as stiff. One pro is that it will be lighter in weight.



From contributor B:
Since some of the 3/4 ply I'm now using measures 11/16", Im also considering going to 5/8". I never thought I'd consider it, but it seems logical to do so.


From the original questioner:
I guess I should have mentioned that we do both euro and face frame cabinets based on customer choice, but they choose face frame 85% of the time. We don't nail our face frames on, we biscuit, spline, or pocket screw - whatever the situation calls for without exposed fasteners.

I thought about the shelf thing, but we already buy a second product for shelving material, meaning that we don't always use the premium stuff for shelves that we use for exteriors. So simply adding a couple 3/4" sheets to our 5/8" order won't be a big deal. The weight issue is the first thing that one of my installers mentioned. I wonder what the actual weight savings will be? I'm, guessing 15-20%.

To contributor B: I understand what you are saying on the thickness thing. It makes sense to at least consider 5/8" since it's only a 1/16" difference. I'm going to have to build a 5/8" box and play with the strength issues, and see if there's a noticeable difference. I'll bang it around, drop it, kick it, sit on it, pile tools on top of it - you know, just like installers do - and we'll see how she holds up. It won't be scientific but I'll post any significant findings.



From contributor C:
I'm sure you would be surprised to know how many builders use 1/2" for case material. I don't see a problem at all with the 5/8". You may have to change or alter some construction methods, but the strength of 5/8" would not be an issue at all in my opinion. I've use both 3/4 and 1/2 for my cases. I've switched to almost all 1/2". Shelving is another story depending on the span and usage.


From contributor A:
Id like to make a one comment on the statement on referring to only a sixteenth difference between 3/4" and 5/8" sheet goods. This trend, where we all get cheated out of a 1/32" or 1/16" on the thickness of plywood, is across the board. If the maker of your 3/4" plywood sells 11/16" as 3/4" they will sell 9/16" as 5/8". It is unfair in my opinion when I buy 1/4" thick plywood that measures exactly 3/16".This is a full 25 percent loss of stated thickness as opposed to the 8.5 percent shortfall when 3/4" comes in at 11/16". They try to cover the deception by calling it some metric size or import versus domestic but its still 25 percent!

As to the slimming down of the thickness case good parts, its okay to a certain point, but there is a line that shouldn't be crossed. I was in some box store and I was looking at a modular vanity and wondered how they could sell it for the price on it with the nice looking raised panel doors until I saw the 1/2" thick sides and the 3/8" thick bottom shelf and zero thicknessed back, etc.



From the original questioner:
To contributor C: I think it's safe to say I've been building in a vacuum over the last couple decades, because I am surprised that someone is building carcasses out of 1/2" material. I'm not knocking it, it just never occurred to me. Using good joinery, proper gluing procedures, and square cuts, I can see it working with no problem.

To contributor A: I share your frustration with supplier dimensioning, but from a little different angle. My frustration is that it's hard to standardize construction methods when you never know how thick a specific material will be. I don't mind so much that actual thicknesses are different than described, but I hate it when it's inconsistent.



From contributor D:
I have been building framed style now for 14 years. All have sides, top and bottom, and backs. Backs are dadoed in with a piece added to the back for hanging. You can sit on them, drop kick them, or just plain drop them. I have never had one fall off the wall or come apart from being overloaded. They are cheaper to build than boxes and I pass that on to the customer. If they insist on , then it is an up charge.


From contributor I:
It's all 5/8" here at my place and all on MDF core unless I can't find it in other than 3/4" or only veneer core. The thickness consistency is never an issue with the MDF core, and 5/8" has never been an issue from a strength standpoint. It's a lot easier on the back as well, from machining all the way through install. All we build is frameless.


From contributor E:
We use 1/2" melamine for almost all our sides and fixed shelves. Adjustable shelves are always 3/4". We build frame cabinets and we've never had a problem with strength or stability. I can stand on the sides of the bases and even jump on them if I feel like it., without any trouble. Of course, if I was doing frameless, I'd definitely go with 3/4". I think you're fine with 5/8 material.


From contributor F:
There are several things to consider. Mixing too many different size materials in your shop makes for a storage problem. The scrape must be dealt with and is now not consistent with other materials. If you want to build cabinets out of 5/8", I believe it will be just fine.


From contributor A:
Actually, if you use a face frame, 1/2" carcass parts will serve the purpose. What I really meant to say is that I dont believe a 3/8" thick bottom shelf is thick enough to serve its function.


From the original questioner:
I have to say I'm more than just a little surprised. I expected a lot more opposition. To contributor F: You make a good point. I hadn't thought about storage issues before, but with my setup I'm pretty sure I can make it work without too much hassle. To contributors C, D, I, E: Your posts supporting the topic encouraged me that I won't be cheating anyone out of anything by going to thinner material.


From contributor G:
I use 3/4" for everything except the backs and they are 1/2". That said a while back I thought I'd build some new shop cabinets and I had some 1/2" that'd been around for a while and decided to use it up. I can't see any issue with the 1/2" and am thinking about switching myself, so 5/8" wouldn't bother me at all. Also, there is a cabinet company that builds their cabinets with 5/32" sides and 1/8" tops and bottoms. I won't mention any names, but I know a guy who sells them regularly for apartments and dorms and he's never had a call back, or a strength issue. If I built like that I don't think I could sleep at night, I'd be counting boxes falling off the walls in my dreams.


From contributor H:
I assume we are talking veneer core plywood. The ANSI/HPVA HP-1-2000 standard is in section 3.13 Dimensions and Tolerances. It states "Thickness: Sanded or unsanded, ...plus 0, minus 3/64 inch is allowed for panels having a nominal thickness of 1/4 inch or more" I can tell you from experience, our 3/4 inch veneer core panels are coming in at .720 inch on average. We are now asking for a 19.5 mm panel knowing it will then come in at 3/4 inch. They call it the industry standard.


The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor M:
I use 5/8 on my entire cabinet box including the back and adjustable shelves. I use 5/8 that way I dont have to have storage for too many sizes of melamine or plywood.



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