An external wooden staircase leading to the rear of 1st floor of our 2-storey bloc of 4 flats needs to be demolished as it is beyond repair. We plan to retain however the balustrade/balcony. 

There is an internal staircase leading from the front door to all flats as a fire escape

The 1st floor is less than 4.5 m above ground. is there a legal requirement to replace the external staircase as an additional exit ?  

Is it a two storey building and why was the external wooden staircase provided in the first place?

Hi Tom

Yes it's 2 -storey, the staircase has been there since the building was converted from a business into flats.

The staircase gave easy access from the car park to upstairs (1st-floor) flats rather than having to walk around the building to get in the front door of the block.

Without more details it is impossible to give a definitive answer but it does appear that the wooden staircase would not be required depending on travel distances and other considerations. Also it could be argued that this could be material alterations and building regulations would apply, therefore contacting the local building control would be necessary. 

Having your FRA reviewed would be necessary and the assessor would be able to give you a definitive answer. He/she would be able to advise if you need to contact the BC.