Cost to open a door way from the ground floor and install stair case to the first floor

[george987]

Hi,

I need to create a doorway from the ground floor external side wall of a commercial property to the first floor (residential).
I assume I have to do the following:

1. Create an opening from the ground floor external wall with lintle and door
2. Create an opening on joists of the first floor to install the staircase from inside ground floor to the first floor
3. Install staircase from inside ground floor to the first floor

I was wondering how much it will cost to do the entire job.

Thanks