Lock Replacement in Detroit, MI

Detroit's older doors, neighborhood by neighborhood

The National Park Service describes the Corktown Historic District, settled by Irish immigrants in the 1830s, where the first residents built detached homes and rowhouses in the Federal style. Woodbridge's Queen Anne, Colonial Revival, Georgian Revival and cottage-style homes went up between 1870 and 1920. Boston-Edison, bounded by Edison Street and Woodward and Linwood avenues, has more than 900 homes built mostly from 1905 to 1925, and Palmer Woods, by Seven Mile Road and Woodward Avenue, was built up mostly from 1917 to 1929.

Doors from these periods were often made for mortise locks, a rectangular case set into a pocket cut in the door's edge. Many current locks are bored instead: a round hole through the face of the door and a smaller one into its edge.

Choosing new hardware for an old door

• Mortise to mortise. A new mortise lock in the existing pocket keeps the door intact, and the original trim can often stay.
• Mortise to bored. Converting means new holes and filling the old pocket, which changes a period door for good.
• Adding a deadbolt. On a door with only a latch, a deadbolt adds a bolt that locks into the frame.
• Matching a bored door. The new lock has to match the existing bore, backset and edge cutout, or the door needs more work.

Replacement makes sense when a bolt no longer throws fully, the cylinder or case was damaged in a break-in, parts cannot be found, or you want a deadbolt where there was none. If the old hardware is sound and worth keeping, lock repair may keep it working instead.

Photos and measurements to gather

• the neighborhood, cross streets and age of the house, if you know it
• the door material: wood, steel or a door with glass
• photos of the lock from both sides and of the door edge
• whether the lock is a mortise case or a bored knob and deadbolt
• the backset, measured from the door edge to the center of the knob or cylinder, if you can take it
• whether you want to keep the period trim

For the city's housing, see Detroit; for the service itself, lock replacement.