Exterior doors often have loads of character, especially when it comes to truly antique doors. This may prompt some homeowners to wonder if it makes sense to install an exterior door on an interior door frame. Additionally, exterior doors are always solid, which makes them better for soundproofing than hollow-core interior doors. Is it ever advisable to put an exterior door on an interior door frame? If so, what is the basic process behind doing this?
Considerations for Moving Exterior Doors to the Inside
Yes, you can use an exterior door on the interior, though there are few practical reasons for doing this. As noted, exterior doors are always solid. However, solid core interior doors are available, though they are significantly more expensive than hollow core doors.
Many factors make transferring an exterior door to an interior door frame difficult and labor-intensive:
Inward swing: Exterior doors always open inward, while your current interior door might swing outward and necessitate different hinge mortises.
Size: Exterior doors typically run 36 inches wide, while interior doors are rarely as wide (about 30 inches).
Symmetry: If the door is paneled, the panels will no longer be symmetrical if you trim off one end.
Trimming: Precise cutting with a professional-quality table saw or radial saw is needed to accommodate the entire door.
Condition: The intended exterior door might be warped or buckled from weathering, making it difficult to install on the interior door frame.
Slabs: Pre-hung doors are easier to install because the door is already hung by hinges to the door frame. For novices, the exterior slab door can be touchy to hang and the swing may be compromised.
Composition: Most slab doors are not a single slab but are like a jigsaw puzzle with various pieces such as rails, stiles, panels, and mullions that combine to form the slab. If you cut too far, the door loses its stability and may fall apart.
How to Hang an Exterior Door on the Inside
If you do decide to hang the exterior door on an inside frame, follow these tips to make the process go smoother.
Dangerous lead-based paint may have been removed from the house interior over the years. Yet the exterior side of the exterior door may have escaped attention. If the door does have lead-based paint, the safest route is to completely strip away the paint and re-paint the door. This often includes metal parts, such as hinges, that have been coated in lead-based paint. Always follow safe procedures for removing lead-based paint, as laid out by the U.S. Environmental Protection Agency.
Trimming Door Width
Since you likely will need to trim the door width, do so by cutting both sides equally. So, to fit a 36-inch exterior door in a 30-inch interior door frame, cut off 3 inches on the left side and 3 inches on the right side. This maintains the visual symmetry of the door. On the hinge side, you would then need to cut new mortises for the hinges. On the doorknob side, the trim would excise the doorknob and door latch set holes, and you would need to create new holes.
Trimming Door Height
If you need to make horizontal trims to accommodate door height in the new door frame, cut along the bottom. Exterior doors receive most of their weathering on the bottom edge. Cutting off even 1/2-inch usually will expose fresh wood. If you have wall-to-wall carpeting, be sure to cut off an appropriate amount from the bottom so that the door will be able to swing over the carpeting.
Protecting Cut Edges
Even though the door will be protected from the weather, all cut edges should be protected with paint or other coatings. Be sure to factor in the added thickness of any coatings that will be applied to edges when trimming the door: usually, 1/32-inch to no more than 1/16-inch. Remove all weatherstripping before cutting.
Preparing the Interior Door Frame
After removing the old interior door, you may need to make a few adjustments to the interior door frame so that it can accommodate the exterior door. Unfortunately, you will not be able to hang the exterior door on the existing hinges. Hinge positioning will be different with the new door. Patch old screw holes with wood putty, sand, and re-paint the entire door frame. Also, use this as your opportunity to repair or replace door stops and trim.