You were planning to replace your old entry door with a new wood door by simply swapping out one door for the other--no messing with the door frame. But just replacing the door (otherwise known as the "slab" or "blank") can be counter productive if your door frame, including the threshold and door jambs, has begun to rot. Similarly, just because your old door frame is rot-free doesn't mean the wall studs have remained square. If the door frame is nailed to warped wall studs, your new door won't easily open and close. You can shave a wood door down, but metal and fiberglass doors aren't so forgiving.

The Pleasures of Pre-hung

Sometimes replacing the entry door and frame is your best option. Buying a pre-hung door means you're getting a door that's already hung on a frame. The pre-hung system also includes weather stripping. How do you select a pre-hung entry door? First, determine whether you need a left-hand or right-hand door (a left-hand door means the lockset is to your left when you stand in the door frame and face outside). Then you can determine the necessary jamb size by measuring the height and width of your old door jamb between the casing's inside edges.

Door Replacement Kits

You have another option to consider. Instead of replacing your frame, you can select a door-replacement kit in which the entry door is pre-hung in a steel frame. This steel frame fits over the old frame for an easy installation. But be warned: you shouldn't install a kit over rotten jambs--rotten means full frame replacement.

About the Author
Ellen Foster is a freelance writer and teacher. She has taught students aged five to forty-five.