Lock Replacement in St. Louis, MO

Old doors, old hardware

About 56.1 percent of St. Louis homes date to 1939 or earlier, per the Census Bureau's 2024 figures. A lock in a door that old may still turn, but replacing it raises a question a newer house rarely does: what was the door cut to hold? Many older doors were made for a mortise lock, a rectangular case set into a pocket in the door's edge, while most current deadbolts and knobsets need round holes bored through the face. A new mortise lock sized to the existing pocket avoids cutting or patching the door. Switching to bored hardware can mean filling the old pocket first.

House types across the city

The city's preservation plan places three house types in particular neighborhoods:

• one-story brick houses with a shaped front parapet, popular from 1900 to 1920, in Dutchtown;
• front-gambrel colonials in Penrose, Tower Grove South and Bevo Mill;
• one-story Neo-Tudor houses of the 1930s and 1940s in St. Louis Hills.

A style dates the house, not the lock in its door. Any of these may still hold original hardware or something fitted decades later. The faceplate on the door's edge shows what is installed now, and that is the starting point for a replacement that fits without extra carpentry.

Historic districts

St. Louis has 18 local historic districts, each created by its own ordinance with its own design standards; Lafayette Square, the Central West End and Shaw are among them. In most cases changes to building exteriors are reviewed by the Cultural Resources Office, so if a lock replacement grows into a new front door or new hardware on the street facade, ask whether that applies before ordering anything. This is general information, not legal advice.

Planning a replacement

Send a photo of the door edge showing the faceplate, the door's thickness, whether the new lock should take your existing key, and whether the house is in a historic district. If the lock only sticks, lock repair may be enough. See lock replacement and the St. Louis page.