Are you sure they are MDF and not Engineered Wood/Particle Board boxes?

Definitely either plywood or MDF

MDF, as plywood can split when cutting. Your face frames will hide the edges. MDF is denser for smooth painting.

Thanks, JWinteriors, for your comment.

When cabinets are well built you will not have split out in plywood. Plywood shelves will not bend like MDF. MDF shelves will have to be turned every six months to a year. MDF is an engineered product. It is made from wood fibers in a resin. MDF stands for Medium Density Fiberboard. When the resin breaks down, it will fall apart and is affected by water quicker than plywood. Advantages of MDF is that it is denser, making it a harder base. Plywood is very paintable because the top and bottom smooth veneer absorbs the sealer, building a smooth surface with coats of sealer. Cabinet makers can buy plywood that is sealed from the factory with a very tough sealer. Paint on MDF sits on top of the product and is not absorbed into the product, so will nick easier.

I am not an expert, but when we were researching our kitchen renovation, thick, furniture-grade plywood was consistently the recommended material for the cabinet boxes, with solid wood for the doors and drawers.

thanks eagleedzines, feeny and Ironbuilders for all of your thoughts. Plywood it is. Now, the KD is indicating the boxes are 5/8" plywood rather than 3/4". Is this a big difference?

Big enough. Can you pay more to get the 3/4?

It's not a very sexy thing to spend your money on, but in the long term, you won't regret it. Nothing will warp or bend and a kitchen gets hard use.

First, using 5/8" thick material for the case carcass is , in my opinion, undersized. The material cost difference between 3/4" and 5/8" thick material is negligible. From a strength point of view it is tremendous.

I am always surprised that no one ever mentions the hardware i.e. drawer slides, glides, door hinges. I've seen so many of these fail. Question your KD on what hardware your price point provides.

Mdf is inherently heavier then plywood. But this does not, repeat does not, make it stronger or more durable. Just put some water on it and you will find out the hard way. MDF splits very very easily. There is also light weight MDF. MDF finishes, paints very well.

Yes plywood does warp. Why? Because plywood is manufactured from cross banded sheets of thin wood plies. There can be a tension between these ply when the sheet itself is layed up. This becomes apparent when one cuts the sheet, it warps then and there, well before it is placed into your kitchen. I's at this point that that cut piece would be rejected. While Im sure someone will have a story about a piece of plywood warping, most likely under extreme conditions, to have that happen after it is installed in your kitchen, well I thick the chances of winning the lottery are better.

What to do what to do? Save yourself some sleepless nights. Do not use MDF on your base cabinets in a kitchen. Plywood can take water, MDF can not. Hope this helps.

3/4" veneer core plywood is premium construction material. 5/8" will work since it supports a vertical weight dispersion.

However, the comparison isn't just in thickness of the material. Generally you will find better construction with 3/4" plywood.

Look for 1/4" backs with-3/4" 'hangers' (pieces of wood side-to-side for the cabinets to hang off the wall) or the whole back should be 3/4". If 1/4" backs are used it is better if they are set into a groove. The backs should definitely not be just stapled to the back of the cabinet box.

Dovetailed drawers are stronger than drawer sides that have been glued and stapled. The drawer bottoms should not be stapled to the bottom of the drawer. Instead they should be set into a groove. The drawer bottoms should be at least 1/4" thick. Thicker for drawers that will hold a lot of weight, like drawers under a stove top that will hold heavy pots and pans.

Look for adjustable shelving, not just in the wall cabinets but in base cabinets, if you have shelves in them. Pullouts in the base cabinets are nice and save a lot of bending.

Regardless of the type of drawer slides, full extension drawers are preferable. There are two basic types, roller bearing and ball bearing. Both are good and have very little callback.

Blumotion drawer slides are very nice but more expensive. They are a superior ball bearing slide with a feature that forces drawers to close softly. Blum also makes a soft close for doors.

Plywood is crossbanded so that it won't warp.
What that means is that one sheet is laid in one direction and the other sheet is laid in the opposite direction and so on until the sheet is built up to 3/4". This is exactly what prevents it from warping.

Plywood will and does warp especially if it is thiiner I.e. less plies. I have personally witnessed it with inexpensive cabinets.

Hi Eagle. Yes altering the direction of the banding, in theory, prevents warping. In the real world there are voids and knots that slip into the mix. One band may be "greener" then the band above or below it. These minor defects put a tension into the board, once in a blue moon. Cutting into one is like releasing a rubber band.

Totally agree with you regarding all else.

lfouser- Cabinets are put together using dowels and glue (maybe even staples) in a production atmosphere. If the material is just 1/8" thicker the dowel used in the construction grabs 1/8" more material, thats huge from a stability point. Also the screws used to attach your hardware to your cases can be 1/8" longer as well and thats equally huge.

True Norm, but my point was that the cross banding is done to prevent the warping. It does not contribute to the warping.

I agree, RJ, that voids etc can creep in, but 3/4" plywood is still superior to MDF. And I totally agree that a piece of warped plywood should never make it past the production process, since warped wood of any kind causes kickbacks, dull blades and out of square cabinets. It would be dumb to use it.

Only time I've seen warped cabinet ply wood is when it was left out in the rain, leaning against a wall. We've been using Procore for veneer panels lately. 9 ply with a last base layer of MDF under the veneer for smoothness. RJ...I stopped using production cabinets so long ago...on this last job the homeowner went for some Chinese KD units for the laundry...came pre-assembled. Face frames were pocket hole screwed to the carcases. And 3/4" plywood sides, dovetailed undermount drawers...Better construction technique than I have seen from our American mass production companies...staples and lots of hot melt glue, random pieces of luan, 1/8" backs! Junk.

I've thought of pocket cutting the frames on. I'd like to see their pocket cutting station.

I dream of the Castlebore TS21. Stand up operation, pneumatic clamping, Porter Cable router with a totally heavy duty end mill, foot pedal one step operation. $2500. Keep looking for used...almost never see them in my area and they are made 17 miles from me!

We can speak of custom cabinets and best quality materials, but the fact remains that custom cabinetry sales do not exceed those of stock or semi custom cabinets. Just like laminate countertops still account for 80% of the countertops in the country. Sure we all want to play in the arena of high end, but don't kid yourselves into believing that the majority of Houzz users, and the population in general, is in that arena.

Still a good education though, for folks who think there is no difference between materials ( and this thread has shown many still do). This isn't the first time the 3/4 and MDF vs ply discussion has come up; won't be the last -keep beating the drum of quality construction, guys. The moral of the story is: do it right, and you'll only do it once.

Agreed, my drum has a hole in it already.