Replacing an Interlock Mortise Lock with a Yale Unity Slim

In this job, we replaced an old Interlock mortise lock with a Yale Unity Slim smart lock 30mm backset on a narrow-stile aluminium door.

The existing Interlock lock was already positioned very close to the edge of the door with a 30mm backset. Because the Yale Unity Slim escutcheon is slightly wider than the old lock, clearance was an important consideration—especially as this entrance also had a screen door.

Before starting the installation, we carefully checked the door alignment and measured the overlap between the aluminium door and the door frame. With a 30mm backset lock, the escutcheon sits close to the door edge, so there is a risk that the new lock may hit the door stop or jamb when the door closes.

Luckily, on this door, the Yale Unity Slim just cleared both the door jamb and the screen door. We were able to complete the retrofit with a clean and tidy result, while making sure the door could still close properly.

However, this may not always be the case for every door fitted with a 30mm backset lock. Small differences in door alignment, frame design and overlap can affect compatibility. The available clearance should always be measured carefully before purchasing the lock or committing to installation.