Do you wonder why some doors warp and other seem to stay as true as the day they were made. The reason is usually moisture. If the door has a higher moisture content when it is made at the factory than the environment it will be installed in, when is dries, it is possible that shrinking and warping may occur.
Now on the reverse side, when the door is made at the factory with a lower moisture content than the environment where it is installed, can also cause problems. Some swelling and warping is possible here too.
Another problem is seasonal changes. If you live in climates with cold winters, running the furnace and drying out the inside air can raise havoc with many wood products. Wood doors take in moisture in the hot humid days of summer and rainy seasons of fall. When winter arrives the cold outside air is dryer than other seasons air, now your running the furnace and drying the air even more. The result is doors warping, or if your lucky, just not latching properly.
It seems to be a battle you can't win. So how to you fight this? Try to store the doors where they will be hung for about 24-36 hours prior to installing them. Apply two coats of finish to all the 6 edges of the door. A single coat can leave the door vulnerable to moisture. Don't forget the important top and bottom. If you miss these areas your likely to experience some problems sooner or later. Follow these instructions for painting or clear sealer over stained doors. Be aware that stain is not a sealer and will not keep out moisture. Its purpose is for color only.
When applying these sealers be sure to keep the doors on a flat surface or fully supported. Once the sealer is applied the moisture content of the door rises, making it slightly flexible. This is caused by the wet sealer or paint soaking into the wood. If the door is not supported correctly, it can take on the shape of the position the door is set in while the sealer/paint is drying. Once the sealer/paint dries, your left with a bowed or warped door. I don't recommend leaning a door against the wall to paint it either. The weight of the door can cause a bow following this process. I have had many contractors tell me the doors fit fine until the painters took them off and painted them. Now you know why...
So let's review:
- Set the doors where they will be installed before you hang them
- Apply finish to all 6 edges of the door
- Use two coats of finish to keep moisture from penetrating your door
While this is no guarantee all problems will be eliminated with warping, swelling or shrinkage, paying attention to details give the best shot at a quality lasting installation.