LDN Fire

I have been asked by a Landlord to advise on potential fire safety improvements to a small three-storey converted terraced house which is now studio apartments/rooms. The single stairwell which is the primary means of escape is lined with Woodchip walls. Not surprisingly I'm finding it difficult to find info in relation to performance of woodchip in terms of resistance to fire and limiting spread of surface flames etc... Initial thoughts would be that it's not be suitable for this application, however when researching online some say it's not combustible as you may tend to think? Does anyone have any knowledge/advise/experience with similar cases? Simultaneous evacuation policy in place, initiated via a fire alarm system with automatic detection within flats and communal areas with call points provided on each floor. Any advise would be greatly appreciated!