Troubleshooting Warped Exterior Doors

Woodworkers discuss the fine points of a small warping problem in a fine custom exterior door. September 8, 2008

Does anyone know the standard for a 3-0 x 9-0 door as far as warpage goes? I have a pair of doors that the active door is warped from the lock mortise in both directions, (1/4"). It was straight when installed and finished but now with the cold weather it has taken on this warp (sticks out on the bottom).

Naturally the customer is not happy. I've thought about installing a truss rod in the length of the inactive door under the astrigal but that is a lot of work and risky. Any thoughts?

Forum Responses
(Architectural Woodworking Forum)
From contributor M:
We have found ourselves in this position before with no real right answer. Doors that tall are prone to some warping regardless of what precautions you take. We try to negate liability by not warranting doors over a certain height, but when you have a good customer who has just spent a lot of bucks thats difficult to take a hard line approach.

A lot of door manufacturers don't consider 1/4" in that height a defect. There is an outside chance in warmer weather it may straighten some otherwise you could set your bottom hinge back and slide the top out to account for the warpage basically splitting the difference. I have never installed a truss rod so I have no idea if that would work, but I do know that once they have gone south, no amount of wedging, clamping, or weighting will fix it. The worse case scenario we have remade doors which I know is not what you want to hear.

From contributor L:
It is always frustrating to have a door warp, but 1/4" warp in 9' seems like it would be with tolerance to the big manufacturers. At the same time, you want to satisfy the client, so you have to do something. I think if it were me I would ask them to wait for another warm season to come and go to see where the door moves to. After it sees another season, you should know the range of movement, and could then plan accordingly.

Contributor M's suggestion of moving the hinges makes sense to me, but if you move them now, and then in the summer the door moves more or less than anticipated, then you may wish you waited a little longer to adjust it.

From contributor S:
I agree with Contributor M. It is best to have a warranty in place before these things happen, but the customer still wants it right. You can twist the frame a bit in the wall - it won't take much to lose 1/4", and then also tweak the hinges a bit. Cross string the opening to see if the frame is in the same plane. Waiting a year is a good strategy, but I rarely see a bowed stile improve.

The tweaking has always gotten us out of trouble; fortunately we have not had to remake a door that was shipped. We have had 85% of our problems with Alder, the other 15% being Cypress.

As for prevention (the best medicine), the thickness of a door has to increase as its height increases, and the species becomes more important. You have to be more firm in this area than you would be with a 36 x 84" door. A 9' door would be a minimum of 2-1/4" in my opinion. Multi point latching is designed to help straighten doors as they latch, but will only do so much, and may fall outside of design intent.

From the original questioner:
Below are the doors in question. Thank you all for your responses. We'll wait for warmer weather and reassess.

From contributor G:
What type of stiles did you use and do you think this had any effect on the outcome? Would you do anything differently? If not then don't feel bad you did the best you could with an organic material that will always be moving some.

From contributor C:
Its a beautiful product. A lot of us have been here for sure. On exterior doors one of my first questions always is what direction is the exposure. Then go from there planning for all conditions. Your warp is within tolerance, as long as you use a substantial weather strip with a good range of resilience your customer should become satisfied. Sometimes you can add a straighter strongback sort of attachment, visually like the astragal but on the warped door and on the inside. Or stress the hinges in the direction you desire. Or even the Hafele truss rod straightener is a good product. I believe they even have a solution for a truss straightener within a groove and veneered over or capped.

From contributor D:
I too have made many doors. I first have some preliminary questions. What thickness is the door? What materials is the door made of? Was the door prefinished prior to delivery? Was it stored at the home prior to install? How was it stored and for how long was it stored prior to install? Also, what is the location of the job? (These questions are to determine how to prevent the problem from happening again).

I had this problem once and we took the door back to the shop, cut and routed into the edge of the door and installed a piece of steel for straightening. We then recapped the end of the door and no one ever knew it was there. It worked for us with no future callbacks.

From the original questioner:
I know the styles had a lot to do with it. When we made the doors there wasn't enough Spanish cedar in the area to produce them, so we used sapele for the center styles (paint grade but the customer liked the grain so much they decided to stain them). I knew at the time that it was risky. I don't like to mix species. Also the doors are only 1-3/4" thick, should have been 2-1/4".

Contributor C - the doors face south so they get a lot of sun. The only place I could put a truss rod would be on the inactive door, under the astrigal. This door is straight so I'd have to bend it to match the warped one.

Contributor D - the customer did everything wrong. The doors sat for two weeks prior to delivery because they didn't want them installed yet. The finish wasn't applied for almost a month. Even with all that they were straight till the cold weather hit.

From Gene Wengert, forum technical advisor:
Beautiful design indeed. The big problem with any door is that the relative humidity is different on the inside and the outside - drier on the inside than outside in the wintertime. This means different MCs and that means shrinkage or swelling from the original manufactured piece.

This difference is totally unpreventable, as even if you sealed the door perfectly, moisture would move inside the door in response to the temperature differences. In the summertime, the RH difference switches and so the door moves in the other direction a bit.

One solution that works, as mentioned, for doors and windows is to put a rigid metal rod in the door to restrain any attempted warp. The comment about mixing species is true, but the two you mixed are so similar, that it is not a problem.

From contributor T:
I've heard of truss-rods in doors before but sticking a straight rod in a door doesn't seem to me like it would do any good Gene. I figured what you'd have to do is rout a groove deeper on the ends and high in the middle (like a Fender guitar has) then tighten down a nut on the threaded end.

From the original questioner:
Actually, you route a wide slot in the edge of the door, say 7/8". At the place where you want to bend, you glue a block of wood so the rod is now bent. As to tighten the rod it will cause the stile to deflect. (The rod wants to straighten out).