How to Fix a Warped Door
As an Architect and Builder, meaning “hands-on” builder, I deal with all kinds of “how do you do thats.” Most of the work I do is new construction so I deal with new materials and products. One of the things I have noticed over the years is I am receiving some interior doors that have a tendency to warp more easily than in the past.
My own guess is some of the new materials used are more susceptible to moisture intrusion; moisture that's in the air, not the door getting wet. I particularly notice it in the closet doors installed in a By-Passing mode, one slides in front of the other, and the even less desired case where a Pocket Door warps after it is installed.
Since these were new products, I would return them for exchange to the door supplier. I did a job however that had six Pocket Doors in it. Two of them needed to be exchanged right away and two more would have had to go back by the end of the job. It was at that point I decided to “un-warp” them myself.
Pocket Doors hang from wheels in a track at the top and slide into a “pocket” frame in the wall. If they are warped, they will rub on the side of the pocket frame not only making a “what the heck” kind of noise, but will mess up the door finish on the face of it. A by-passing or regular hinged door will just “look bad” but the finish won’t get scratched. There is a slight chance in the by-pass, but the door would have to be warped significantly to rub on the one behind it (if in the guides at the bottom). The regular hinged door just won’t meet the door stop evenly if it is warped and sometimes you can tap the stop to meet the door instead if the door is fairly straight. This technique depends on whether the door has been installed, caulked and painted already. If so and it is a noticeable warp, you will need to take the door off and “tweak” it.
You will need two end supports, like saw horses, and a long straight item like a wall level or very straight board (if you can find one these days!). Determine which way the door is warped, usually bowed in the middle somewhere and place the bow up with the door flat on the horses at each end. Then place weight, like from the weight-lifting set you got for Christmas and is now in the garage, on the top of the bowed area, then “set and forget.” Actually, you don’t forget. You need enough weight to push the bow down, but not so much that it will warp the door the other way, which can happen.
Depending on weight, door material and weather conditions it will take a couple of hours to even a few hours. After a couple of those hours, check it with the straight edge for progress. The door will have some “memory” of the warp in it so it needs to be weighted long enough for the door to “forgetta bout it,” but not warp the other way.
In the case of a Pocket Door it is a much bigger job because of the work involved in getting the door itself out of the frame. You have to remove some of the stopping trim which means caulking and re-painting when done and the door is back in place. This may not be a “do-it-yourselfer” job but you can determine that for yourself.
I have found it to be much better to “weigh out the warp” than to return the door, especially after it has been painted and fit for where it goes. It saves refinishing (beyond touch up) and all the time, energy and possibly the same problem with the new door anyway, so I “re-warp” as needed on the job.