staircase in shop

[cupcake]

The staircase leading from the ground floor of my shop to the first floor [also my shop] is closed in. I want to remove the wall and put bannisters in [may even be in there already] to open up the space, but my builder says I must keep the wall and the door at the bottom to suit fire / building regs.
I have been in numerous shops with open staircases.
Is he right?

 

[DAZB]

You may either have to put an enclosed lobby with a fire door on the 1st floor instead or provide a sprinkler system and a hard wired and certificated fire alarm system with numerous break glass points. It may also be worth checking if your insurance specify any conditions regarding this. Not an expert on the regs for commercial properties so maybe someone can add to this.