A practical, site-ready guide to DIN WC/Privacy (bathroom) locks: sizes, compliance traps, fitting notes, and a printable fitter’s template + inspection card.

The sash lock is the workhorse of mortice DIN locks — reliable, versatile, and almost always the first choice when both latching and locking are required. For fire doors, it’s a proven solution when used with certified keepers, intumescent protection, and correct installation.

A mortice lock is fitted inside the door leaf, in a pocket (“mortise/mortice”) cut into the edge of the door. It’s the opposite of a rim lock, which is surface-mounted on the face. Mortice construction gives better security, a cleaner look, and compatibility with modern Euro cylinders and lever furniture.