doors

How to Fit a New Internal Door: Hanging, Trimming and Fitting Hardware

Gabriel

01 Dec 2025 — 3 min read

Fitting a new internal door is one of those carpentry tasks that intimidates many DIYers but becomes straightforward once you understand the process. A door that swings smoothly, closes properly and latches cleanly is entirely achievable without specialist skills — it requires careful measurement, patience with a plane, and systematic work. This guide covers fitting a door from scratch into an existing frame.

Choosing the Right Door

Standard UK internal door sizes are 1981 × 762mm (2'6") and 1981 × 838mm (2'9") — the 762mm width is by far the most common in houses built before 1990. Measure your existing opening carefully: the clear opening width (between the door stops) should be approximately 6mm wider than the door leaf to allow for clearance. For accessibility, Part M of the Building Regulations recommends a minimum 775mm clear opening width in new and altered dwellings.

Hollow-core doors (around £20–50) are the budget option suitable for rooms without acoustic requirements. Solid-core doors (£50–150+) are heavier, give far better sound isolation, and hang more smoothly. For a principal bedroom or a home office, solid-core is worth the premium. For a bathroom, use a moisture-resistant (MR) grade door — standard hollow-core doors will absorb moisture and distort.

Measuring for the Frame

Measure the door opening in at least three places — top, middle and bottom width, and left, right and centre height. UK houses are rarely perfectly square; the frame opening itself may vary by 5–10mm across its height. The door needs to fit the widest and tallest points, then be trimmed and hung to provide consistent clearance.

Target clearances:

Sides: 2mm each side (allows the door to swing without binding)
Top: 2mm
Bottom: 6–8mm over carpet, 10–12mm over a hard floor (to allow air circulation)

Marking and Trimming the Door

Hold the door in the opening and mark with a pencil where trimming is required. Remove 3–4mm at a time with a hand plane or circular saw. For the hinge side, aim for a dead-straight edge — use a long straight edge to check. For the latch side, a very slight bevel (2–3° angled away from the room) prevents the leading edge catching on the door stop.

Never trim more than 6–8mm from a hollow-core door — the outer stile (solid timber rail) is typically only 25–35mm wide, and cutting into the hollow section leaves no structural material for the latch mechanism.

Fitting the Hinges

Standard internal doors use two 75mm or 100mm butt hinges (three for heavy solid-core doors). The top hinge is typically positioned 150mm from the top of the door, the bottom hinge 200mm from the bottom, and the third hinge centrally between them.

Mark hinge positions on the door edge, then use a marking gauge and chisel to cut a recess (housing) exactly the depth of the hinge leaf — the hinge should sit flush with the door edge.
Screw the hinge to the door.
Hold the door in the opening at the correct clearances (use folded card as spacers), mark the hinge positions on the frame, and cut corresponding housings in the frame.
Screw hinges to frame, hang the door, and check it swings and closes correctly. Adjust by deepening or packing out hinge housings until the clearances are consistent.

Fitting the Latch and Handle

Most internal doors use a tubular mortice latch (around £5–15 at Screwfix) combined with lever handles on a sprung backplate. Mark the centre of the latch at the required height (typically 900–1000mm from the floor for adults) on the door edge and face.

Drill a hole the diameter of the latch body (typically 25mm) into the door edge to the required depth — use a sharp bit and a guide to keep the drill horizontal.
Insert the latch and mark around the faceplate. Chisel a shallow recess so the faceplate sits flush.
Mark and drill the spindle hole through the door face — align with a bradawl from both sides.
Fit handles on both sides, connecting through the spindle.
Close the door to mark the strike plate position on the frame. Chisel a recess and drill the latch bolt hole.

Common Problems and Fixes

Door binding at the top hinge side: Hinge recess is too deep — pack out with thin card.
Door swings open on its own: Frame or floor is not level — adjust hinges to compensate, or fit a magnetic catch.
Rattling in the frame: Door stop needs adjusting closer to the door face.