MDF for Door Panels

Woodworkers discuss the suitability of MDF for the raised panels in interior house doors. April 24, 2006

I have a large paint grade door job coming up and got beat up pretty bad on price. At the price point established, the contractor has agreed to accept MDF panels rather than wood. They are 1 3/4" cope and stick doors and the panels will be raised and have a 1/4" tongue. They're also just 2 panel doors, so the top panel is going to be quite large. Does anyone see problems with this construction?

Forum Responses
(Architectural Woodworking Forum)
From contributor F:
My opinion: a solid panel door will work with MDF. There are companies that make stick and cope from MDF. I wouldn't, because it does not have the strength required for the punishment a door will receive in its lifetime (in the stiles and rails, the panel will last forever).

From contributor J:
As long as they are interior doors and you are using carbide tooling, I see no problem. I've built plenty of doors with MDF panels, and not one returned because of panel breakage.

From contributor B:
As long as your rails and stiles are of poplar or a similar wood, you will have no problems with MDF panels. The door takes the beating on the rails and stiles, versus the center panel. I would still leave about 1/16" overall for movement, just to be safe. You might look into Ranger Board (or similar) versus standard MDF. It will be a bit more expensive, but cuts a sharper detail edge and takes paint a bit easier on the open cut surfaces.

From contributor C:
The panels on the door should have a 3/4" thick tongue, not 1/4". Sandwich a sheet of 1/2" MDF to both sides of a 3/4" center piece with waterproof glue to create your finished 1 3/4" thickness. If you want a deeper profile, you could go down to 1/2" on the tongue, but no thinner. Check the available stacked cutter heads to see what they typically accommodate.

From contributor K:
Simpson Door Co. makes exterior paint grade doors, MDF panels, Douglas fir stiles and rails. They have had good luck with them.

From contributor M:
Not a problem for interior doors. The stability of MDF can actually be a bonus, since there's less likelihood of having the paint crack on the joint between panel and frame. As mentioned above, you might consider a larger groove and keep your tongue thickness at 1/2" or larger.

From the original questioner:
Thanks to all who responded. It looks like it's okay to go with MDF as a panel material. I'm also looking at a new set of cutters that will give me the 1/2" tongue that some have suggested. I too will feel better about having a thicker tongue. That was actually one of my main concerns that a 1/4" might not be strong enough.

From contributor F:
To be slightly argumentative, I think if someone or something hits an MDF panel that has a 1/4" tongue hard enough to break it, that that would be abuse. I would not hesitate to use it.

From contributor A:
I believe most people are not so concerned about the panel tongue thickness as to the overall cope/stick profile for a 1 3/4" door. 1/4" is fine for 1 3/8 interior. 1/2"-5/8" is more typical for 1 3/4 and 3/4" is for 2 1/4" exterior.

From contributor F:
Oh, you're right! My addled mind missed that one.

From contributor S:
Not trying to stir up a hornet's nest here. Just out of curiosity, what do you mean you got beat up on price? Did you bid it and specs changed, or did you make a major blunder in proposal on materials or labor? I want the answer so we can help so you don't get put in this situation in future. It sounds like you have not built many passage doors. I learned the hard way years ago.

From the original questioner:
Thanks for the offer, but I too have built many passage doors over the years. What I meant by "beat up" was in order to get the job, they wanted the lowest possible price I could come up with, hence the use of MDF for the panels. This is a first for me. The order was quite large (140 doors) and I feel comfortable with my numbers and I now have the job.