How to Replace an Interior Door

Before you begin, measure the width and height of the old door (the thickness of all but the oldest interior passage doors is standardized at 1 ⅜ inches). Bring these dimensions with you when you buy the new door "blank"—unlike a "prehung" door, it won't be surrounded by a jamb or drilled out for the lockset. Doors come in just a few heights—80 inches is the standard—but a wide range of standard widths.

CAUTION: Door manufacturers use shorthand to describe a door's width. So a 3-0 (pronounced "three-oh") door is 3 feet, 0 inches, or 36 inches, wide—not 30 inches.