While many cabinet manufacturers either tout their use of plywood or offer it as an upgrade, there are a number of downsides to its use. Though it offers a few positive qualities that distinguish it from solid wood, I would argue that its use should be limited to instances where those qualities are critical and plywood's problematical qualities cannot readily be avoided.
I have, for many years now, constructed cabinets, mostly for kitchens, using 3/4" hardwood plywood. This plywood and various other ‘sheet goods’ such as medium-density fiberboard and particle board, which come primarily in 4’ x 8’ sheets, have been the standard approach to kitchen cabinetry during my lifetime and at least back to the years post WWII. My understanding is that the standard cabinet depths we have become accustomed to were established to make efficient use of 4x8 sheet goods in rebuilding Europe after World War II. So, 2’ for base cabinets, 1’ for uppers, and that 4’ is divided quite nicely with little waste. The division of the 8’ length is a bit trickier, but three 30" tall cabinets get you close to the 96" in length. A 30" base cabinet with a 4 1/2" base (recessed to create space for toes) and a 1 1/2" counter provides our standard 36" kitchen counter height. These ‘standard’ dimensions work, though they are not necessarily ideal or best for all tasks and storage issues.
So, for those with the means, custom cabinetry - provided by joiners, like me, allowed for variation to suit different heights, tastes, and kitchen spaces. Of course, we have constructed all those custom-sized cabinets using the same 4’ x 8’ sheets, which do not adapt efficiently to many other sizes. If one cuts a 4’ sheet at 25" instead of 24" one is left with a piece that is less than 23" or less than is needed for the ‘standard’ cabinet depth. That piece could be cut again at the standard 12" for an upper cabinet - leaving 11", which is too narrow for another cabinet side. I have personally cut these pieces to 4 1/2" to form bases for cabinets but two of these from 11" leaves one with 2" and a kitchen does not require many of these 4 1/2" pieces.
One of the claimed benefits of plywood is that it reduces waste since most of the plies are peeled off a log like you peel paper towels off a roll. So, in the manufacturing stage, this is very efficient and hence profitable. However, as I hope you can see, there is a tremendous amount of waste in the end use if one strays from the ‘standard’ cabinet sizes. There are nifty computer programs that will lay out parts on a sheet to minimize waste, but even then, I find there is a great deal of waste generated from a single set of kitchen cabinets.
But it is not just the amount of waste that is at issue, but the quality of the waste. I can find uses for solid wood pieces often as small as 2" wide, but I have no use for a piece of plywood that size. If nothing else, my smallest pieces of solid wood scrap can end up in my neighbors’ wood stoves as kindling, and the sawdust can be used in compost. But between the plies in plywood are mysterious bonding agents, which are known to be toxic. Here in Vermont, the burning of plywood is banned, and you wouldn’t want to inhale the combustion products from your wood-stove, so it must end up in the landfill alongside the plastics and other unnatural products.
There may be more waste in the production of solid wood boards from a tree trunk than in the production of plywood, but that waste is not only non-toxic, it is useful in many ways, hence my quest to reduce the use of plywood in my cabinetry.
Except in rare cases with specialty products, plywood edges must be somehow covered to hide their flaws and protect them from the damage to which they are highly susceptible. The finish plies of hardwood plywood are usually so thin they cannot be measured with a typical ruler - clearly less than 1/16". If that thin ply is nicked or slightly peeled back, the structural layers of the ply are revealed, which are normally of different species and hence different coloration and grain, leaving a defect nearly impossible to repair satisfactorily.
These delicate edges are most often covered using edge banding, which is usually another thin piece of veneer. This may be thicker than the finished face veneer, but still subject to the same damage and difficulty of repair. I have used several methods of edging plywood with solid wood, which solved the issue of edge vulnerability, but none of these were aesthetically satisfactory or really cost-effective.
In my opinion, the only truly satisfactory uses of plywood are those that fully wrap the exposed plies, such as door panels that are set into a groove in the door frame. Here, the one true advantage of plywood, its dimensional stability, is an improvement over solid wood panels that must be allowed space to expand and contract. Ironically, the original purpose of frame and panel construction was to allow for that expansion and contraction while producing an overall item, such as a door, that is more dimensionally stable. So, the plywood advantage is really only evident as less cost in this instance.
As mentioned above, plywood has much greater dimensional stability than solid wood. Due to its structure formed during a tree’s growth, Solid wood expands and contracts significantly across the grain. This is not true along the length of the grain, so a 1”x12”x10’ board will stay quite close to 10 feet in length while varying seasonally in both width and thickness. All traditional woodworking and joinery used known methods to accommodate this peculiarity of wood. In some cases, this is an asset, as in long trim pieces on houses. Carpenters can butt-join pieces of solid wood to form a skirt board 40 feet long with no issues, but many newer materials used for these purposes expand and contract equally in all directions, which makes PVC trim, for example, that is 40 feet long very dimensionally unstable, requiring special installation techniques to allow for expansion and contraction with changes in temperature.
Plywood is formed by alternating the grain direction in serial plies so that when well bonded, the dimensional stability of wood along its length applies to both length and width. This is a traditional method improved by modern adhesives. The one flaw with this construction is that the plywood is three-dimensional, and the stability is only two-dimensional. If a carpenter nails a 4x8 sheet of plywood to the framing of a house, it will be very stable, but if the same sheet is not attached to restrict movement, it will be very susceptible to changes in air moisture and prone to warping. This is often not fully understood, even by experts. I once had an architect ask me to make cabinet doors out of simple cut pieces of 3/4" plywood. When I raised the issue of warping, he replied that he thought plywood was stable. This was in his own home, and he convinced me to construct the cabinetry as specified, with the understanding that he would live with any warping ... which he did.
One clear advantage to plywood is its lower cost. This is due to the fact that the central plies are composed of less aesthetically pleasing (and hence less costly) species and can contain defects which would be unacceptable if seen. In recent years, due to the costs of manufacture and shipping, this advantage has been lessened. Though the cost advantage is of immediate benefit to the manufacturer and the consumer, it is not clear that this benefit holds over the lifetime of the product. We have all seen nicked, delaminated and unsightly plywood. While small defects can be very unsightly and hard to repair in plywood, they can be unnoticeable and sometimes even add to the charm of solid wood pieces, which are also much easier to repair satisfactorily. Solid wood furniture that is dozens or even hundreds of years old can still be attractive and functional. When it is not, this is often due to glue failure. Given the vast improvements in glues due to advances in chemistry, there is no reason that items produced of solid wood today could not last even longer.
Plywood had certain advantages in simplifying manufacture in the twentieth century. Given the improved capabilities of computer-aided manufacture, there is no reason other than a lack of imagination for plywood to dominate the production of wooden products in this century. Considering the value of trees in absorbing carbon, the issues we face with limited landfill space and the accumulation of toxins in our environment, why would clean, renewable, and long-lasting solid wood be our first choice for cabinet and furniture construction?