From time to time a homeowner or contractor will notice that their door is protruding past the jamb and does not seal properly.
This could be caused by a number of factors, from the home shifting, to the door being installed slightly out of plane, or warping of the door slab.
This video will demonstrate a simple method to check if a door slab has become warped.
A quick way to test if a door has become warped is the string method.
Get a length of string—chalk string will do—that will allow some coverage of the top and bottom of the door.
First lay the string beneath the door and hold it under foot.
Next, draw the string over the strike-side of the door by hand.
Finally, inspect the string to see if the clearances are the same from the top to the bottom. If the slab is warped, then the bottom, center and top clearance will be significantly different than each other.
Repeat this process on the other side of the door to ensure an accurate reading. A slight amount of clearance is expected, but it should not exceed 3/16 inch.
