How to cut down a door
When finishing a basement requires you to shorten one door or several doors, follow this procedure and keep these other guidelines in mind for a successful and aesthetic application.
Things to know:
A standard door opening is 82” tall. When your application doesn’t allow for this – such as a generally low ceiling or underneath a soffit - you can take up to 1 ½” – 2” off the bottom portion of the door without any real noticeable difference. What you may see is that the bottom rail/style of a panel door will be a little narrower and the corresponding handle height – assuming a pre-hung door – will be lower by that amount as well. If you happen to be using a flush door you probably won’t see anything different.
If you have two doors fairly close to one another – one is OK at the standard height and the other needs to be cut down – from an aesthetic viewpoint I would opt to cut down both doors to the same height. This way when you look at the two doors from the opposite side of the room the tops of the doors and the handles will align.
If you need to cut off 3 – 4”, here’s how I would tackle the problem.
First, I would look at the number of doors requiring this amount of shortening. For a single doorway that was going to be 3” shorter and out of the main focus of the room I would probably still use a pre-hung door. I would take equal amounts (1 ½”) off both the top and bottom of the door slab. Whatever you cut off at the top of the door, you’ll need to shorten the door frame that corresponding amount. This amount would still be OK for a panel door.
If multiple doors require 4” to be removed I would purchase slab doors, (not pre-hung) jambs and hinges and have the carpenters set them up individually. The primary reason would be to avoid a situation whereby the handle heights become so much lower that your doorway ends up looking like a “hobbit” door. The handle bore then would be made at the standard height. Also know that the handle height in terms of relative position to the rest of the door will be different than a standard (full-height) door. 4” - (2” top and 2” bottom) is the maximum I generally allow to be cut off a panel door. After that I look for alternatives.
More than 4”? I would purchase flush doors. The carpenters then set up each door individually using a hinge jig and door bore kit. If you want to make the door more attractive, add some molding in a rectangular pattern after the door is cut.
Flush door slabs work great to make crawl space access doors. In fact, depending on the height of the opening, you may be able to create a large entryway into your crawlspace using only one door slab.
This is the procedure we use with a 6 panel hollow core pre-hung Colonist door.
Disclaimer- Make sure you follow all OSHA guidelines when working with tools. Use safety goggles and never remove blade guards from saws.
First determine the amount you need to take off. The next step is to remove the door from its frame by removing the three hinge pins.
Use some masking tape and run a band of tape around the door at the bottom making sure the tape is placed where the cut line will be. If you need to cut the top - put some tape there as well. The tape will help to protect the door from being damaged from the saw blade during the cut.
Mark where you are going to cut on the tape. If you have a felt tipped pen, these lines are easy to see. Make your cut or cuts.
Now from the piece(s) of the door that was/were cut off, remove the “skin” of the door from all four sides. What remains will be put back in the bottom portion (and top if applicable) of the doorslab to prevent the door from warping.
Inside the hollow core door slab is a lot of cardboard. You will probably need to carve some of this out in order to put the piece(s) back in.
Once space has been made use some wood glue and re-insert the piece(s). Make sure everything is flush. You may want to add a few brads to hold everything together. I would also use clamps while the glues dries.
Set the door aside to dry.
Now, whatever portion was taken off the bottom of the door, you need to take that amount off the two leg portions of the door jamb. Mark those and cut the side jambs accordingly.
The top works the same way. What you cut from the top of the door you cut from the top portion of the “leg” or side jambs.
Once the proper length of the jambs has been achieved, reinstall the top jamb piece (if need be) along with any removed doorstop.
Once the glue on the door slab has dried, reattach it to the frame and install the door as you normally would.