Hi all,

I've read through previous topics on rim night latches on fire doors and can see its a bit of grey area and I am struggling to find one that is suitable for my clients needs. (FD60 and Black)

I was thinking a mortice option may be safer and was thinking of going with a euro mortice night latch, but the door already has a sash lock installed. Can it affect the integrity of a door to have two DIN lock cases installed? 

This is a FD60 timber front door for a flat for context 

This usually becomes an issue because manufacturers of timber-based fire doors tend not to use night latches for burn tests and that night latches are not CE or UKCA marked. Except for new doors with multi-point latching & locking, flat entrance doors would usually be fitted with a mortice sash lock with a euro cylinder including a thumb turn for keyless egress. 

If you can trace the door to its manufacturer you can contact them for information about the fitting of two mortice locks. I am aware of evidence of performance for two deadlocks fitted to a timber fire door, but depends on core construction, position of lock, lock-case dimensions and the necessary fire rating of the door. Which might not be FD60?

This guidance might be useful too: http://firecode.org.uk/Code_of_Practice_hardware_for_fire_and_escape_doors.pdf