Unpainted MDF Filler Strips Near a Dishwasher

Is it safe to have a cut MDF edge located close to a dishwasher? Cabinetmakers talk about materials, water resistance, and the meaning of "quality." July 9, 2007

I am a kitchen and bath designer and have two local custom cabinetmakers who work with me. We have a client whose contractor thinks it is okay to plane down our MDF dishwasher filler strips to allow for more room in the dw opening. We made it to the specs of Bosch, which call for 23 5/8 to 24 1/4. This variance is to allow for retrofits or manufactured cabinets which may be a standard 24in wide... We made it to fit as it should be. The dw has side fillers on it to allow for retrofit, etc. and Bosch says to remove them if you have custom opening. We said we would remake our fillers, but contractor got huffy and says now he is simply going to plane down… not repaint them. Thus the sides will be exposed to heat/steam from dw. My cabinet man and I think this is wrong. Please give me any input.

Forum Responses
(Cabinetmaking Forum)
From contributor B:
As long as the client understands that this is the contractor's decision and the contractor is ultimately responsible, I'd let it go. If it makes you feel any better, get the contractor to sign a waiver for any steam damage. Ultimately, the contractor is the one who has to stand behind the house. He'll go back on his subs but he's ultimately responsible.

From the original questioner:
Thanks. I guess that is ultimately true but I actually care about whether the client has issues down the line or not... and as most cabinetmakers know, it always comes back on us somehow if some part of the cabinetry is damaged regardless of what contractor does or does not do. I just want to know in the professional community what the wisdom is on proceeding with raw MDF fillers next to this dw.

From contributor P:
I think if he tries to actually plane MDF, he'll change his mind. Personally, I don't use MDF for anything that is for mounting. I use either scrap oak or Baltic birch for nailers, mounting plates and fillers. I think if he sands down the MDF face, it will have to be painted or it will fall apart in short order - if paint will even hold it together, which I don't think it will.

From contributor B:
Let me change the subject just a little and see what the consensus is, since you've broached the subject. I always leave 24" for a dw no matter what dw they pick. I don't want them to call me in 2 years and say they just didn't like the Bosch or F/P and want a conventional dw and they need me to modify the cabinets so they can squeeze something in. I feel like a 3/16" gap down each side of the Bosch is certainly not bad. How many custom fit the dw opening at 23 5/8"?

As for longevity of MDF, I don't use it anywhere except on doors. I think it will swell with the steam and be a problem. Paint will slow the problem, but I just don't use MDF for anything except doors or drawer fronts that will be painted.

From contributor J:
I always build for a 24" opening and have never run into a problem. If someone wanted the opening at 23 5/8", I think I'd try to talk them out of it because of retrofits. Also, I'd never put MDF, raw or otherwise, next to that dishwasher door. In a few weeks it will look like pate.

From the original questioner:
Thanks for the input. I will make sure my cabinet man reads this. However, in our humid and hurricane prone area, we have never had a problem with MDF in the last 8 years. Obviously there are many opinions on that... You do have to treat it a little differently with screws etc., but we typically only use on doors also. And these are conversion varnish painted slab doors. This is a very modern kitchen and we decided to cut it close and we have fillers. By the time they need a new dw, might be ready for other changes too. And the fillers could always be cut down to fit new one anyway. I think the issue I have is the frustration in dealing with a commercial contractor who knows little about residential remodels/kitchens, and the complexity that high end appliances have brought to the arena. I am not responsible for installation, but I actually do care about the outcome of the job and want it done right. Not to mention the obvious... If he planes down MDF fillers, you will see the raw part somewhat. Who wants that? But, alas, I am in the deep south where some good old boy contractors are simply annoyed that I know anything other than "how to put the pretty colors together."

From contributor E:
Hand the client some scraps of raw MDF and tell 'em to put in some water or hold over a pan of boiling water. I'm sure they will then insist that the contractor do things the right way.

From contributor M:
MDF is a poor choice near a wet area. The fact that he wants to cut and replace the finish is of little consequence. What you need to understand is that there is no finish that is waterproof. Some finishes are more water-resistant than others, but none will prevent water from penetrating. Finishes that are cross-linked are the most resistant, but water will find its way to the substrate.

This is not a slam on you or your cabinetmaker, please understand. But I find it a poor choice to use MDF in a wet area like a sink or near a dishwasher. Most of the economy builders around here won't permit it, and I doubt that the thought of a Bosch dishwasher ever crossed their mind.

I would suggest that you understand your limits. Once your cabinets are installed, you cannot keep people from making modifications like this. If you "actually care about whether the client has issues down the line or not," then use better materials in areas like this.

It sounds like you have come to us for some ammunition to use against the builder. I would say, don't be surprised when a builder acts like a builder. Instead of trying to change him, why not change your practices?

From the original questioner:
Thanks. I appreciate the thoughtful advice. I spoke to my cabinet man about the MDF and he reiterated that there were certain conditions that were met that might not show entire story about using the MDF. And again, we have never had a problem and we are only doing high end work. However, I am going to discuss this more fully with him. I am not looking for ammo against builder. Most I work with respect my knowledge and our final product, and welcome the expertise we bring to the table. However, some are more pigheaded. I really just wanted to get the professional feedback that I have received thus far and really do appreciate the forum. It is a silly ego thing anyway, when he had already made new resized fillers per the builder's instructions! He just got huffy when we did not show up same day to install.

From the original questioner:
I appreciate your candor, but I am not sure that I understand. This seems to be a wordy phrase, but the meaning is vague and unclear to me. "I spoke to my cabinet man about the MDF and he reiterated that were certain conditions that were met that might not show entire story about using the MDF. And again, we have never had a problem and we are only doing high end work."

High end is one of those abused terms in our industry. I prefer to speak about the level of quality, which, in my view, includes 1) materials used, 2) construction techniques, 3) style and appearance, 4) fit, and 5) finish.

The cost of a 30.5" filler piece is minimal. And if you are working with clients that are paying for a designer, I would assume that your budget could easily absorb the cost for a more appropriate material. Contrary to what your cabinetmaker has said, this is not one of them.

I appreciate you taking the time and energy to educate yourself about our trade. It is commendable, and a greater effort than I see with other designers. I can say that it is not necessary to produce furniture quality cabinets in order for them to be high quality. It is, however, a disservice to your client and our trade to offer low quality materials and/or poor construction techniques with a nice style and good finish, and call it high end.

From the original questioner:
Constructive criticism well taken. He debates the use of the MDF vs plywood filler in this spot. Says it is okay in this application with frameless/euro cabinets. He has no screws on outside facet, etc. You have inspired me to ask him in greater detail what he means and discuss further. I try to be more knowledgeable about the product I sell. All of my cabinetry is designed by me and runs through my business, so I am ultimately responsible and I am happy to find this forum to further my education on cabinetmaking and materials. It has been great.

From contributor I:
I've used MDF for well over 20 years for all my cases, either raw or veneered 2 sides. Never one moisture related callback - period. Besides, MDF has evolved, just as has particleboard. The one job I did, against my better judgment, that failed miserably, was one that the customer insisted on plywood. Glue skips and delams out the ying-yang. Plywood is for roof decking and concrete forms. Engineered board, MDF or PB is superior if used (keyword) correctly.

From contributor M:
You'll have to explain to me how to use MDF or particleboard correctly. The failures that I have seen are when water is introduced to sheet stock. Plywood, in my experience, has held up much better than MDF or PB because it is a continuous strand of material. Particleboard (MDF included) has the grain of the particles running in random directions, and when water is introduced, it does not have the ability to return to its previous shape, where the cell walls of the plywood are somewhat intact, and can shrink back to its original structure once the water has evaporated.

Don't get me wrong, I believe there is a place for MDF and particleboard, and I do use it. I don't use it in areas that are exposed to unusually high levels of moisture and heat. So please, what am I missing here? How is MDF and particleboard the superior material, and how is the correct way to use it? I am familiar with Exteria, but don't know of a good water resistent PB.

From the original questioner:
Interesting turn this thread has taken. I get this from clients occasionally, asking the difference between MDF and plywood. I have been around long enough that my reputation for doing quality work along with my cabinet men precludes many clients from asking too many questions. They have plenty of referrals to go by. But it does come up and it is interesting to get the various responses to this from this forum. Our boxes are all plywood, drawers, etc. Doors painted can be MDF and I can tell you we have had no problems or callbacks either. Let's face it... anything that gets a lot of direct moisture or water is going to have problems. I have seen it all disintegrate after H.Ivan. My own plywood cabs and MDF doors held up quite well (with conversion varnish) after water intrusion, dampness, and nine months of no a/c after H. Ivan. I will say that my dw panel is not looking so hot with the sloppiness of loading wet dishes into it and dripping on face. The MDF we have used has proven to be quite dimensionally stable around here. I am sure there are applications that are not prudent… this I am learning. I have never dealt with particleboard at all.

From contributor I:
By correctly, I mean machined, tight fitting dados, not butt joints. Not getting overboard on unsupported span. Plywood will fail if it has glue skips in the plies (very common). Water continuously dripping under a sink will rot a hole through plywood in short order. I'll stick with the MDF any day.