If you have never worked with doors within an old house, you may have the reasonable assumption that you can remove a slab door and replace it with another slab door on a one-for-one basis. After all, the door has been hanging there for decades. How hard can it be to re-hang?
What often happens is you spend countless hours trying to get doors to fit into door frames. Sometimes, it is virtually impossible, because the door frame gets out of square when the house's foundation subsides. So, it is not your fault at all if the door doesn't fit well.
Exacerbating the problem: previous owners may have gradually adjusted the door to fit that ever-changing door frame. Bottoms get shaved off; sides get planed, hinges get tweaked. Eventually, you are left with a door that fits only that one, unique door frame—just like a glove.
When the Door Doesn't Fit the Frame
One trick you can use when re-hanging a door is to reconfigure casing and trim around the door. The door remains as it is and everything around it is slightly rebuilt to fit around that door. This is not a hack to solve all of your problems, but it will take care of any issues you might have with excessive gaps.
Tricks to Install a Larger Door in a Small Frame
Cut the Door
Cutting down parts of the door is usually more reliable than paring back the door frame. Most slab doors have between 1 and 4 inches of solid material that run around the perimeter of the door. This material can be cut down with a radial saw, table saw, or circular saw.
The tops and bottoms of the door afford more room to cut than the sides. On the hinge side, mortises will need to be recut. The latch side is more difficult because of the position of the door knob.
Readjust, Plane, or Sand Down the Door Jambs
If the door frame surrounding the door is smaller than the door, you may be able to readjust the frame. Most door frames are installed with space between the frames and the outer studs. Replacing the shims with thinner shims may give you more room to expand the door frame.
If you only need a little bit more space, you may be able to sand or plane down the door jambs without removing them.
- Electric nailer
- Finish nails
- New door casing and trim
- Screws that are slightly longer than current hinge screws
- Adjustable door hinges (optional)
Remove Trim and Hang the Door
Knock off all of the trim around the door, except for the hinge-side. In many cases, it is possible to remove trim without breaking it. In other cases, you may need to break up the trim. Medium-density fiberboards, or MDF, is especially prone to accidental breakage, so with this, it is often more expedient to demolish it and purchase new MDF trim.
With those three sides of the trim removed, hang the new door as you normally would.
Assess Level and Swing
You want your door to be level and swing smoothly. Set a level on top of the door. Slowly swing the door open and closed, watching the bubble on the level. If it ever goes out of level, take note of where this is happening and mark this arc on the floor with chalk or removable painter's tape.
Adjust the Hinges
In many cases, you can correct level at the hinges, by tightening or loosening the screws that hold the hinges to the casing.
Installing special adjustable hinges gives you more room to play with. These hinges can be adjusted up to 1/4 inch vertically—a significant distance when it comes to hinges. By adjusting one hinge in one direction and the other hinge in a different direction, you can make major changes in the door's level.
Add Longer Hinge Screws
Even normal, non-adjustable hinges can be adjusted slightly. One way to pull hinges tighter is to remove the existing screws and replace them with slightly longer screws. Ram these in as tight as possible if the door is scuffing at the opposite end of the frame. By contrast, you can add a cardboard spacer cut to the size of the hinge mortise if you need to close a slight gap at that opposite end.
The door should clear the finish flooring by about 1/2-inch. Keep in mind that this is the finish flooring, not the substrate. So, if it is sub-floor right now and you hang the door with a 1/2-inch clearance, it will drag once the finish flooring is installed.
Build Casing and Trim
Build a casing that follows the configuration of the door. The inner door casing can be moved incrementally inward (towards the door) by adding wood shims. Tack into place with an electric nailer rather than hand-nailing.
Once the casing is in place, the trim follows the lines of that inner casing. With trim, you especially will want to use an electric nailer, which drives thinner nails than traditional finish nails.
Paint trim and casing to complete the project.