Plywood Thickness for Cabinet Construction
From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
I certainly encourage you to use the nailer with 1/4". You can possibly try larger heads if the screws are pulling out... The tip of the screw should be in more solid wood and should be long enough that withdrawal is not an issue.
From contributor X:
First off, a lot of houses were built with their cabinets having no backs at all. It was cheaper - plaster or drywall was the back. Backs were used to keep the dust, mice, bugs out and were intended to blend in with the inside of the cabinet, making the appearance match. Cabinets were secured to the walls with the use of back rails, cleats and shelving. 1/8 inch skins (plywood) and 1/4 inch also was used as back material, but was not intended for fastening to the wall. Back rails and cleats were still used to secure through. With the use of 1/2 inch and 3/4 inch materials, being more solid and rigid, they could be used to secure to the walls, some with back rails and cleats and some not. It all depends upon what the customer wants and what the job requires and how you sell the job (how you want to build them). All backs were glued on and secured with nails, staples and even screws. When the back was exposed, 1/2 inch or better was used. Like an island cabinet for support. Mostly, it's your call as to how the cabinets are made. Besides, it's only wood, plywood, masonite, etc.
From contributor T:
You can not pull through and attach any receptacles to a 1/4" back. A nailer or shim is desirable for a plum fit. Very few walls are ever straight, especially over long runs, and having the backs pull off, as you mentioned, is a real bummer. You might want to consider euro screws with a 1/2" back (much better than staples). 1/4" material distorts under load and is more susceptible to moisture damage. With your face frames, the carcass has its rigidity, but a 1/2" back goes a long way in stabilizing the carcass. In extreme applications, 3/4" works even better. Loose 1/4" works best to scribe the toe kicks to the floor so you can lose the shoe molding.
From contributor L:
I've always used 1/2" backs for wall cabinets. Makes for a much better wall cabinet. Weight is not an issue. Cost might be.
From contributor J:
If you're using framed cabinets, why not use 1/2" for everything (except exposed ends)? I have used both methods and honestly, the 1/2" is much faster if done correctly, and you can't tell the difference in appearance or strength. The only time I would worry with 1/2" boxes is setting a heavy piece of granite on them... and I'm sure they would still be fine.
Wood Doc, you didn't mention why you suggest 1/4" with a nailer. I'm curious?
From contributor F:
I glue and staple 1/4" ply on even the base cabinets (which is a rare thing here in Eugene). I use 3" plywood back nailers, seen from the inside of the cabinet. One at the top of an upper, then a 1 1/4" small hidden back nailer under the bottom shelf of the upper. I edge band the plywood nailers on uppers. Plywood doesn't split, and pull throughs are never a problem. If you run your screws only through the nailers, the 1/4" backs will never pop out. Plant-on backs like these make for a little more room on the first shelf on an upper, the one they like to put their dinner plates on – that's the reason for the hidden nailer under the shelf. One shop in town doesn't even use an under the shelf (uppers once again) nailer or hidden nailer. Their installers hand drill a pocket screw hole and secure the bottom with a screw, which works well, but is kind of cheesy.
From contributor E:
I build mostly frameless cabinetry with 3/4" sides and 1/2" backs and this works very well for me. The idea of using 3/4" for everything is interesting, though. Especially since the 1/2" ply is as expensive, and sometimes a little more, than the 3/4". Hmm...
From contributor C:
I started using 1/2" backs about two years ago because my supplier ran out of the 1/4" pre-finished birch that I normally used. It was so much easier to cut the 1/2 back and slide it into the dado that I never bothered with the 1/4" ply with 3/4" nailer again. My cost is about $6-7 per sheet more for the 1/2". To me, the additional cost of the sheet versus the time I spent goofing around with the nailer/plywood makes it a wash. The weight is not a factor in my opinion. I also like the thicker back for attaching drawer hardware.
From the original questioner:
I knew I would get many responses with this. I appreciate all of them. I think I'm going to make the switch. Just seems the pros are more than the cons. Do you rabbet the sides, top and bottom for the 1/2? Or do you let the back run through and butt the top and bottom to the back?
From contributor E:
I cut a 1/4" dado on all my cabinet parts and a rabbet around the edges of the backs. Makes for a quick and simple process and assembly, and the backs are locked into place.
From contributor C:
I only dado the side panels and let the 1/2" back run through the full length of the box. I then butt the top and bottom into it. I pocket screw the top and the bottom to the back. I usually run screws up the back to secure the back to the sides.
From contributor Z:
I pretty much stopped using 1/4" plywood for anything when it finally started coming in at a smidgen under 3/16". That was it. I used to make the cabinets with the 3/4" stretchers (with 1/4" backs). I found with the 1/2" backs, the time that I saved not having to make the stretchers, edge-band, pocket hole and install far outweighed the cost of the 1/2" ply. Also, at 3/16" I could no longer use my dado cutter to make a good fitting slot - 7/32" is as small as it goes. I could use the blade and a 1/16" chipper, but that produces too much tear out. So now it is 1/2" backs and 1/2" drawer bottoms.
From contributor H:
I use 1/2 for my backs, banded on the bottom and stapled and screwed to the back of the cabinet. Applied end panels hide last cabinet side. Cabinet is automatically squared this way as well. The fall-offs are used for drawer bottoms and drawer sides, pocketholed to each other from underneath the bottom with 1/2 recess for undermount slides. This way there is no notching necessary. When kitchen is assembled, my scrap pile is real small!
From contributor B:
Everybody keeps mentioning 3/4" tops, bottoms, and gables I don't understand why anyone uses 3/4" material for anything. 5/8" is all I use in my shop, including the backs. A quick 1/4" dado to the top, bottom, and sides (run the back through the shaper) and you're good to go when it comes to assembly, no glue necessary. Is there any specific reason for this or is it just preference?
P.S. The backs set 3/4" in with 1/8" gap to suck the cabinet to the wall during install with 2 1/2" panhead screws straight through to the studs. When you're done, they're both sturdy and nice to carry!
From contributor E:
We use 3/4" for frameless cabinetry. 5/8" would look flimsy and provide less meat for fastening hinges, drawer slides, etc. For face framed cabinets it's just personal preference, I guess.
From contributor K:
For us, it's a matter of simplicity and economics. Using 3/4" all the way around provides a lot of advantages...
1. Marketing - It is and looks beefier. Place one cab next to other, and simply say "a picture is worth a thousand words... wouldn't you agree?" or "Which would you rather have supporting your new granite top?".
2. Strength - Better to stand up to granite, concrete, tile or other heavy tops over the long haul.
3. Buying power - You can get a better deal on 5 loads of 3/4" than you can with 3 loads of 3/4" and 2 loads of 1/2". Ply distributor spends less time culling and loading and is able to earmark more of a shipment towards a specific destination as opposed to sending 5 sheets here and 2 sheets there. It's more profitable for them, as it costs the same amount of gas to deliver whether they deliver 5 sheets or 5 loads, and they don't have to break a load to pull the sheets out, and strap them down. Not to mention 5 trips out to your shop vs. one. This all has an effect on pricing... at least in our case. If it doesn't in your case, talk to your ply distributor about these factors and your willingness to bulk purchase... you may be pleasantly surprised.
5. Less shop real estate - Without a forklift, you can store 80 sheets of 3/4" ply within reach in one 4' x 8' area. With a forklift, this capacity obviously increases. This uses less shop real estate than stocking two separate sizes. Now, you could, of course, stack the 1/2" above or below the 3/4", but you would not get the volume discount of ordering 5 loads at a shot of one product.
6. Cut-off storage - No need to have separate cut-off storage for two separate sizes of material.
7. Assembly - More glue surface equals more strength. Screws have more mass to bite for installing hinges (you can use 3/4" screws vs. 1/2" screws) and pocket-holes; and as I believe someone else mentioned, easier to assemble 3/4" than it is with 1/4". Added benefit, no need to add another process when assembling (i.e. - adding a nailer), as your nailer is built-in. Seems counterproductive to me to cut a back for a cab and then have to cut and attach additional beef to hang it. KISS...
8. Ease of ordering - No need to figure out how much you need of one size vs. the other for a project... just order one size. By taking advantage of buying at a bulk discount and being able to store it in a small footprint, you are also able to increase profits. Imagine if before gas shot up this past year, and everyone started adding fuel surcharges to everything and increasing per unit costs, you had purchased a 6-month supply of ply. Not only would you have saved on the bulk purchase, but the added fuel surcharge to boot. You would also have had a nice cushion, while appropriately charging new customers this market driven anticipated increase, instead of sucking this increase up and reducing your profitability. Now, imagine the reverse - you order JIT, and after selling a job or two at one price, the gas increase bites you in the butt. If you don't have a provision built into your contract for this... guess who gets to lose money? And it's those little hidden money grabbers that, over time, lead to financial challenges.
Well, these are some of our reasons.
From contributor N:
1) Preaching about misleading a client into believing that 1/2" isn't strong enough doesn't sound good to me.
2) I'm sure there is more granite installed on FF cabinets made from 3/8 to 1/2 plywood in one day than there is on 5/8 and 3/4 plywood FF cabinets combined in one year. Hell, they even install it on those 3/8 melamine junk cabinets.
3) Yes, buying in bulk can save money, but it ain't for everyone, and paying 25 - 30 dollars a sheet more for 3/4 vs. 1/4 for space savings or ease of ordering is just plain out stupid. If you are trying to justify a small amount of storage area, build a rack to hold a couple of units. The savings will be minimal over one unit vs five units of plywood. To get a real savings over one unit, you would need to order truck loads.
There are no pros to using 1/2" backs or 3/4 plywood on FF cabinets.
From contributor J:
As far as the strength issue goes, I'll give an example of a job I did recently which involved removing some very cheap 70's cabinets and replacing them with face frame cabinets.
The cabinets that were removed were in a Home Economics classroom. They were made of mostly 1/8" masonite. Shelving was thicker, of course (1/2"). The masonite was groove and dadoed into cheap frames with an 1/8th saw kerf. They appeared to be hot glued and stapled. They had withstood 30+ years of abusive use from teenage kids. I'm telling you, when we started tearing them apart, it took a small sledge and a crow bar. They were unbelievably stout.
I guess the moral is... Once you have several cabinets mounted together and socked to the wall, you can nearly drive a tank over them. I just don't see the justification for using 3/4" for cabinet parts. In my opinion, 1/2" works great and will support virtually any top if they are built well for weight transfer to the floor. I don't think you can fully appreciate the strength of the components we use until you try to dismantle or destroy them.
From contributor K:
I don't buy that a 3'-5' cabinet with a 1/4" back is going to hold the weight contained in that cabinet more safely than a 3/4" cabinet. Seen too many examples to the contrary. If that's the case, why not use 1/2" shelves? Although, I must say, that out of all the cabinets I ripped out over the years, I can't think of one example of a 3/4" cabinet being easy to take out or literally falling apart with a swing or two of a hammer. They are usually a pain.
With regard to 3/8" cabinets, most of these are stock cabinets, not custom, and most have a drop from the top of the base cabinet to the corner supports, due to fabrication methods, and this leaves a lot of weight on this edge material. I know that I can't be the only one over the years that has seen the effect this has on these cabinets (buckling, splits, racking, drawer misalignment, countertop cracks) when ripping out old heavy tops (tile, concrete, granite).
With regard to 1/4" backs, am I also the only one who has seen these literally coming apart on the wall from overloaded cabinets? Customers do not know the meaning of overloaded and will rarely break out a scale to weigh the contents before putting them in the cabinets. With very few exceptions, I can't tell you how many of these I literally disassembled with only a hammer; they usually collapse with a few whacks. Original assembly is also a factor.
With regard to granite tops on 3/8" cabinets... I agree, as they are mass-marketed, but they should also have added supports. Most guys who fabricate heavy tops (and we do) will tell you that support is critical for longevity. A 3/4" cabinet will resist racking with the movement of the house much better than a thinner cabinet any day.
From contributor R:
I dropped the 1/4" backs on uppers quite some time ago in favor of 1/2". I've always used 3/4" gables until about a year ago. A contractor asked me to build his cabinets out of 1/2", since that was what he had been used to buying and installing. I wasn't too certain I wanted to deviate from my norm, but I had been needing some more storage in the shop so I decided to try some 1/2" uppers for myself before I agreed. I have to admit I was surprised at their strength and I feel they will be plenty durable, and what a pleasure to lift, load, and install.
Only one thing actually bothers me about the 1/2", and that's the thought of placing 20lbs/sq" granite on 1/2" gables that have been dadoed. I'm still going to recommend 3/4" over 1/2" for granite and other solid surface materials. I'll sleep better at night and in my opinion I'll be doing my customer a service.
From contributor E:
I think one more important point to be made here is which materials to use in relation to your market. I try to get clients who are willing to spend a little more for better quality. I don't use less expensive materials to make more money, I use better quality materials to charge more money. I figure the cost of materials plus a percentage of markup. My labor costs are based on time. If I get materials for less money, I charge the client less. If I pay more, I charge the client more. That's why it's custom - I charge for what I do and to make a profit, not to compete with the guy using cheaper materials.
At the end of the day, 1/2" ply will probably support granite just fine. I personally have no use for 1/4" ply on my cabinets. But that's my opinion. The way I look at it is, would I use 1/2" for my own house to save a couple dollars? Or use 3/4" ply and not worry about it?
It depends on your specific market and what you can sell, though. Just look at the last issue of Cabinetmaker magazine to see the proof. Pricing for those jobs is all over the map. And I couldn't compete with 70% of the bids submitted.
From contributor B:
Contributor K, you made some good points, but the only thing that you said that might be better for me specifically is having the cabinets look beefier (though it hasn't been a problem in eight years).
All I buy is 5/8" material for everything, including backs, which means no need for nailer (5/8" melamine is plenty strong). You also mentioned pocket holes, I'm assuming to connect the gables. All my cabinets get drilled (using a 23 bit doweling machine), glued and pressed. Screws take care of finished ends and hidden connections. Sinks and corners are about the only thing that get screwed through the gables (still doweled on the bottom). As well, there are no problems with any of the Blum or Accuride slides and hinging.
In my shop I do have a forklift and an 18' tall sheet rack beside my saw holding 150-200 sheets at any given time (tried buying bigger bulk before but the shop was too congested). Also, a separate vertical rack for the odd 1/8"-1" sheets I may need and my cut-off storage is mixed together, be it 3/4" MDF or veneer, and it's still small (I'm just that good).
As far as "buying power" goes, 99% of the time I use 5/8" white or hardrock melamine, and I get volume discounts on every 50-sheet stacks of either. I still think 5/8" is the way to go, but in the end it's up to the cabinetmaker.
P.S. A row of 6 cabinets means there are 12 gables on their vertical - plenty strong for the heaviest concrete or granite c-top with proper build up.
From contributor O:
Some of you must work in a different kind of market. In 30+ years I've never seen a cabinet fall off a wall and heard of this only once and that was a cabinet that had not been fully secured to the wall. The few I've pulled off a wall that weren't screwed on were difficult to remove. I believe the only value difference in 1/4" with nailer backs over lone 3/4" backs is to the manufacturer, not to the end user. I could argue this all night long. I use 1/4" backs with a nailer setup for a French cleat ledger to simplify installation.
From contributor H:
Contributor B, you are the only one in this thread that is using melamine and everyone else is arguing about plywood. When I use melamine construction, it is always 5/8 throughout, as 1/2 melamine is hard to find and expensive. I am from Montreal originally and many more thicknesses and colours are available there, so I would use both 5/8 and 1/2. Lots of seconds available from the mills where one side is perfect and one side slight defects. We used the #1 material for shelves and #2 for gables and bottoms and backs. Used to be able to get units of 5/8 for 9.00 sheet in hard rock maple. Here in Florida the selection is smaller and seconds are unheard of.
From contributor D:
I for one don't think it really matters if you use 1/4", 1/2" or 3/4" backs, as long as the cabinet is built properly (so it doesn't fall apart or off the wall) and can support the loaded weight. I don't think by using 1/4" backs, you are cheating anyone. Or producing a cheaper product than someone using a thicker back. The customer really doesn't care. It is just a sales pitch aimed at convincing the customer to buy from you. Or convincing yourself that you build a superior product to your competition. All the customer wants to know is what does it look like and what does it cost. A good salesman can sell the customer on whatever the good points are of the cabinet. If it has melamine interiors, then you sell the easy clean feature. If you are using all wood, then you push that angle.
The people that use 3/4" for their cabinets are more than likely using a variation of the 32mm system. You almost have to use 3/4", whether it is particleboard or plywood. Everything is based on line drilling, doweling or screwing the boxes together. That gets rather hard to do with anything other than 3/4". You can argue all you want about which is better to use under granite tops. From an engineering stand point, it doesn't matter. Unless the top is only going over one set of cabinet sides, multiple cabinets put together with 1/2" sides will support any granite top. The more sides you put under the top, the less the total load will be on each individual side. All you have to do is divide the weight of the top by the number of cabinet sides. Using melamine sides has less strength than plywood sides. But it is still very unlikely that the granite top will overpower the cabinet sides.
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