(A)    Our method of construction allows the door height to be trimmed down no more than 1” from the bottom rail and ½” from the top rail for a total cut down allowance of no more than 1 ½”. The door width can be trimmed ¼” on each side for a total of no more than ½”. Calculate the size of door that you need, take closes standard size door and if needed subtract the trim allowances, any height or width that is not within these specifications is considered to be a custom size door.Click on the custom sizing link for examples and pricing information.