If you are selecting doors for existing metal frames, you should be aware that deformations or misalignments due to incorrect installation are common issues. Many of these imperfections are minor and not visible to the naked eye but may cause problems when fitting the door leaf. The solution is simple—if professionals measure your existing metal frames, they can adjust a standard-sized door leaf before dispatching it (within certain tolerance limits).
If you already have the door at home and it does not fit into the metal frame, here’s how to modify it.
SHORTENING INTERIOR DOORS
How to shorten doors?
Shortening doors by a small amount can be done by a skilled DIY enthusiast. The most common type of interior doors, rebated (polodrážkové) doors, are best shortened from the bottom. This eliminates the need to recreate the rebate (falc). If shortening a door with a sandwich structure by up to 1.5 cm, it is possible to cut the bottom part, where the MDF or solid wood frame is located. If the door needs to be shortened by more than 1.5 cm, the entire bottom frame must first be cut off, and a new wooden strip must be glued to the bottom edge to maintain the door’s structural integrity.
When should doors be shortened from the top, and how?
If the door scrapes against the top of the frame (the lintel), it is usually due to a misaligned or warped metal frame. In such cases, shortening the door from the top—by a maximum of 1 cm—is necessary. Shortening a rebated door from the top is technically more complex as the rebate must be recreated. The top of the frame is first trimmed, a new rebate is shaped, and the modified section is finished with edge banding. If the door needs to be shortened significantly, the top frame must be removed entirely, replaced with a new wooden strip, and then refinished.
- TIP: If the door lightly scrapes the floor and needs a maximum of 3 mm of clearance (e.g., after installing new flooring), the issue can often be resolved using spacer rings on the hinge pin. These rings, available in finishes matching the hinges, can raise the door without cutting. A maximum of two rings per hinge pin can be used.
- TIP: Before shortening a door, measure it carefully. The clearance under the door should be 4–10 mm to allow smooth operation.
NARROWING INTERIOR DOORS
How and from which side to narrow doors by up to 0.5 cm?
Narrowing doors should be done by professionals, as improper modification may compromise the door’s structure. Narrowing should be performed on the hinge side rather than the lock side. Modifying the lock side can misalign the handle and lock holes, making installation difficult, especially with rosette-style handles.
For doors with a sandwich structure, up to 0.5 cm can be trimmed from the hinge side. The wooden strip inside the door frame is cut down, the rebate is reshaped to match the original, and the modified area is covered with edge banding.
How to narrow doors by more than 0.5 cm?
For reductions over 0.5 cm, a larger portion of the internal frame may need to be removed. A new wooden strip must be inserted to maintain door stability. If the door has a honeycomb core, part of the honeycomb structure is compressed inward, and a wooden strip is glued in. For chipboard (DTD) cores, the cavity must be routed to fit a new wooden insert before refinishing.
- TIP: When narrowing doors, consider the door design. If the panels or glass inserts are symmetrical, excessive narrowing may make them look unbalanced. If ordering custom-sized doors, a manufacturer with a workshop can adjust the size while ensuring a symmetrical design.
STANDARD DIMENSIONS OF INTERIOR DOORS (mm) - Sandwich Construction
