Lock Replacement in Cambridge, MA

Old doors in East Cambridge

East Cambridge is among the city's oldest neighborhoods, and its doors show it. The Cambridge Historical Commission's 2022 draft report on East Cambridge traces how it was built. Many homes there date from 1820 to 1870, starting with small wood-frame workers' cottages and moving on to single houses, double houses and rowhouses. Builders had turned to denser tenement housing by the 1890s, and construction there stopped in 1929.

A front door from that period may have outlived several generations of hardware. Each change can leave its own bore holes, filler blocks and strike cutouts in the door and frame, so the next lock has to fit what is already there.

Mortise or cylindrical

If a door of that age carries a mortise lock, a box set into a pocket cut in the door edge, changing to a modern cylindrical lock can mean reworking the door. A new mortise body sized to the existing pocket avoids that. Before choosing:

1. Measure the door thickness and the distance from the door edge to the center of the knob or cylinder, called the backset.
2. Photograph the door edge with the faceplate showing, and the strike on the frame.
3. Note any old holes that the new lock's trim would need to cover.

When to replace instead of repair

Replacement makes sense when a lock body is cracked, the latch no longer holds, or parts are no longer made for it. If the lock still works and the only problem is lost keys, rekeying keeps the hardware in place. A lock that sticks but is otherwise sound may only need lock repair.

Renters should check with the owner first. The owner is responsible for maintaining locks on dwelling unit entry doors and other exterior doors under 105 CMR 410.270, part of the State Sanitary Code. This is general information, not legal advice.

What to send with a request

Include the neighborhood, the door (front, unit or rear), the photos above and whether you want to keep your existing key. The lock replacement page describes the service itself. For the neighborhoods behind these old doors, see Cambridge.