A fire door is tested as a complete assembly, so every hinge recess and lock mortice cut into the leaf has to be protected again. This guide explains fire door hinge pads and lock kits using the BWF Fire Door Alliance and the Guild of Architectural Ironmongers: what each one does, how to choose pad thickness and the right kit for each lock, and a worked eight-door HMO example. It lists Astroflame and Interdens prices checked on 27 October 2026.