Repairing Warped Interior Doors

The fix for some closet doors that developed a bow along a long stile could include some innovative hardware — or not. March 22, 2013

I posted a while ago about some 2-1/4" thick doors I built that have started warping. I've been going back and forth with the owner and I think we're on the same page as to liability, (a short recap, doors were not painted properly and still six months plus after delivery some of the edges are not properly coated! One is also on a closet which contains two hot water tanks producing a lot of heat! He has agreed to pay for two of the doors to be replaced.

One has a stile that warped inward at the bottom about 1/2" and I think I will have to re-make that one. The other door has an outside rail that has a bow in it. I had the thought of installing a truss rod (for those of you not familiar, guitars employ a steel rod inserted into a curved recess in the neck which allows you to counteract the forces of the strings by tightening the rod against the curve.) I'm thinking of making a full length truss rod I could insert in the back of the stile and use to pull it straight again. What do you think? It would be significantly easier, quicker, and more profitable than building these doors again. The door in question is a closet door, not the utility room door.

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Forum Responses
(Architectural Woodworking Forum)
From contributor D:
I doubt a steel rod will keep a rail from warping. A 10" wide rail 2 1/4" thick will move regardless. If it doesn't bend a rod with it, it will crack around it. You have a tough situation, better solved by insulating the tanks than trying to reinvent the stile and rail door. Still, you could benefit from engineered core in the rails, stiles, and panels as well. Even further, a great moisture barrier before painting is thinned epoxy.

From contributor M:
Before reinventing the wheel, take a look at the Häfele Planofit Panel Straightening System. Ideally this is installed into door and panels before they are needed as machining a warped door or panel can be a challenge.

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From the original questioner:
Just to reiterate this is a plain old closet door, not the utility room door. Also for clarification I'm not trying to straighten the rail, I'm trying to pull about 5/16" of bow out of a 80" tall stile. I don't see the Hafele system working on a door like this. More importantly it would have to be an invisible fix. So having said all that do you still think the truss rod is a waste of time? If so I guess I'm making another door.

From contributor G:
I think you should try the truss rod idea with a piece of all thread. What do have to lose? It works on garage doors. Have you guys tried ripping and flipping the stiles?

From contributor T:
Great looking doors. I can't see you pulling 5/16" bow in 80" out of a stile. I also would be concerned as to why so much movement, are these solid wood stiles, what kind of wood? Even with unfinished bottoms a 1/2" on an 80" interior door is a bunch.

I have had luck ripping off an offending stile and basically re-coping the ends of the rails, but with the applied moulding that creates a new wrinkle and you would have to remove it. I think you are stuck building new ones, maybe you can salvage the panels.

On another note, we have gone back and forth over the years with painters not sealing the bottoms. I put little stickers on all our doors and forward a sheet to the contractor on how to seal and properly care for our doors. Usually it’s to no avail and I’ve been in your position many times, mostly exteriors. I also tried sealing the bottoms ourselves but had an issue with wicking up the end grain on stained doors. It seems that more times than not we eat it trying to maintain a good relationship with our customers.

From contributor M:
You are clearly closer to the problem than I am, but in your original post you stated: "I'm thinking of making a full length truss rod I could insert in the back of the stile and use to pull it straight again." That's exactly what the Planofit is. If not on this door, perhaps in the future you'll give it a try. It is ideal on sliding doors where the back will not be seen. In Europe they install a pair of these in all tall sliding doors as a matter of course, knowing that there will likely be some warping on tall solid slab doors. I've seen it used in stiles here in the USA and the results were acceptable. The interesting thing with this system is that it can remove a bow from either direction.

From contributor D:
I have done as Contributor T suggested above, albeit with 1 3/4" doors. I had bearing guide router bits made of the cope cut only to match our big tenoner. In the days before our CNC it was the only way to make a radius cope. Now the only time I use them is just this scenario where the door is too unwieldy to work on the shaper. These bits in a hand router work fine.

From the original questioner:
Contributor T - there were 14 doors altogether and only 2 have moved noticeably, which considering the circumstances I think is not too bad. Truthfully there were several other doors that were off a lesser amount, 1/8" plus/minus, but we went through with a 6' level the other day and found that the problem was how they were hung - not plumb!)

I should also say the door that looks like it moved 1/2" is likely not off that much, as the jamb was out of plumb almost that much at the top. That was more of an eye measurement using a 6' level, so I'm not sure exactly how much warp there really is yet. Plumbing the jamb is not going to completely get rid of the warp, but it will minimize it a bit. Considering it's got to be close to or over 100 degrees inside the closet vs. 78 outside, I'm surprised only the one warped!

Just as an aside, not only were the bottoms not painted but when you open the other (non-utility) closet doors you can see the edge of the stile still only has my original coat of primer on it. I'm also pretty sure that the faces of the doors have significantly more paint than the backs. The painters have literally been putting coat after coat on all the woodwork in the place. They just keep filling the gaps with caulk and painting. There are gaps in the builtup crown moldings of over 1/8" half filled with caulking, it's a complete mess. I'm going to check the humidity level next trip in as the heat is at a constant 78 degrees. There are now many gaps in the floor also, some close to an eighth of an inch!

Contributor M, my idea was to insert the hardware so it's inside the stile in the same manner they fabricate guitar necks (nothing visible on either side). This client is not going to go for having hardware mounted to the face of the door, even though it's inside a closet. He's already spent well over $1m on this build so given the choice he'll pay for a new door. My problem is more of a time/schedule one as these doors are pretty time consuming to produce.

As for construction the doors are made up with three pieces of 4/4 soft maple milled flat and glued up. Let sit for several days or more then milled again for flat. I glued up the entire batch as full lengths and used the flattest pieces for stiles and cut the rest into rails. I really think the problem is a combination of how dry the unit is getting and how poorly the doors were coated.

I'm now leaning towards just re-making the doors. I don't think ripping the stile off will work. I'd have to remove so much of the moldings and do so much jigging up, it would probably take just as long. I just wanted to run it by you guys first and see what you all thought.

From contributor O:
Cause of warp: I think it wise to consider the cause of the warp. It could be environmental, or it could be a wet or over dry lamination in the stile. Try getting a reading on a moisture meter from each of the three plies in the problematic and non-problematic stiles. This may help you isolate and diagnose.

If you put in a truss rod and a wet board continues to dry out/equalize, then you may be making monthly visits to adjust the truss rod. Since the door is paint grade, the problem stile can be ripped off in 90% of its width and replaced, or routed down on each face and then replace with new wood. This should avoid making a new door.

Plumb vs. flat: I go only so far with levels and this whole plumb discussion - plumb is a subjective term. I do not think a door hung 1/8" out of plumb will warp (especially at 2-1/4" thick). The only way to tell if the door and the jamb are flat is to string them. Stretch a taut string from corner to corner, coming right off the face of the jamb, or blocked up equally on the door, diagonally so that the two strings cross each other in the center. They should just touch, telling you that all four corners are in the same plane. If they miss by 1/8", then one corner is out twice that - 1/4".

I have seen many times where an irritated carpenter slams his level up against one jamb, then the other, saying 'plumb' at each, when the jamb indicates a twist of over 1/8". Correct this and the problem goes away. This problem is magnified in paired doors.

From the original questioner:
Just to clarify I don't think the jambs being out of plumb caused the doors to warp. I think it was the factors mentioned previously. The jambs being out makes some of the other doors that are flat look like they're not. On the utility closet we used a level and one side was plumb vs. the other being off quite a bit. I agree that this isn't the best way to check, however it was a quick and easy way to see if there was a potential problem there. With a good 6' level and a careful eye I should be able to see a difference of 1/8"(forget about letting the contractor do it).

So then we brought in a laser to check the planes of the opening more accurately, and the top corner of the jamb was off by close to 1/2"! So when they pull that jamb back into where it's supposed to be, it should better indicate how bad the door really is. I do still think that door may need to be replaced since at first glance it does seem warped – the bottom pulled in towards the closet. I wouldn't think just replacing the stile will solve that issue?

On the other door I'm thinking about the truss rod for, (non-utility closet), the stile is actually bowed, so possibly a fixable situation. Of course the two doors which have problems are both in paired situations making it even more obvious!

From contributor D:
Adding to what Contributor O said, please determine if the door is truly warped or they are hung out of plane. The string line method is by far the easiest on doors with applied mouldings, otherwise you can usually just stand back and see if a door is warped. I think you said one side of the jamb of one of the pairs is 1/2" out in 6' is not acceptable. So if the jambs are brought into plane and the door warp is minimal, a little judicious tinkering with the hinges can probably get those babies looking real good down the middle. By tinkering I mean take the hinges and either sliding them back in the jamb or forward depending what you want to happen with the mating corners. It takes a very small amount of moving the hinges to make up a lot of distance in the meeting stiles in the center. You may have to fill the screw holes and re-drill but that still is better than making new doors.

I would like add I have adjusted many doors in this fashion either for slight warping, walls out of plumb, structures moving and settling, etc. and it is absolutely acceptable. As for the success rate you are batting around 15%, not very good. I know the debate rages on, solid, or stacked solid, but these doors for me wood have been poplar on a fingerjointed pine core 1/8" veneers. You have way to much solid material all fighting to do what it wants to do.

From the original questioner:
I’m still not sure which solution I'm going to try. You might be surprised though at how much you can move 2-1/4" maple with a little pressure. I already did a little test when I first thought of the truss rod and can get about 1/8" - 3/16" with pretty moderate pressure.

Normally I'd be very discouraged having 2 doors out of 14 warp on me. Keep in mind though that the way these doors were handled, painted, and installed would void pretty much any reputable door manufacturer’s warranty! Had I known about the utility room beforehand I'd probably have opted for stave core on those particular doors. That's what happens though when a homeowner decides to design on the fly!

I had also though about moving the hinges, but because of the buildup casings I'm very limited to how much I can move. Anything more than say a 16th of an inch will be noticeable. I'm going back end of the week for another small project and will see if they fixed the jamb. I will also bring some blocks and string to check how bad the warped door really is.

From contributor A:
I would try cutting off the stile on the edge of the molding. Glue up a new stile and dowel, domino, or slip tenon it. Make the joints a little sloppy and glue it back together with thickened epoxy. I have fixed numerous old doors in this manner. I’ve never had an issue with this type of repair. I always use BIN primer on pre-primed millwork, because it is a sealer.

From contributor C:
I ran into this a few years ago on a few mahogany pocket doors. We didn't have time to re-make them so we ripped within an inch if the stile profile, cut the stile down the middle, added 1/2 thick rift sawn oak down the middle as a sandwich, and re-glued. We sanded to thickness and packed the pores, finished them, and moved on. They are dead flat to this day.

From the original questioner:
The doors are now flat! I ripped the offending stiles off and glued on new flat ones. In the end it just seemed like the easiest and safest bet.