When adding a first floor addition the staircase is a key component of the design, placement is almost always the first consideration, what space in the existing floor plan do we have to place the stairs?
Commonly close to the front door and central to the first floor plan, are the top of the stairs opening onto a living room. Second consideration may enclosing the stairs in with walls and doors to create a seperate space or having them quite open with a void and filling the ground floor with light from an upstairs window and with that a skylight over the stairs, window or a pendant light. Thirdly are we having the underside of the stairs open or using the space for a store room, study or storage? and then fourth consideration is the style of the stairs.
These are all points to consider at the initial design stage with your builder and designer to meet your desired outcome.
The photo seen here is of a recent addition in Holsworthy including a timber balustrade with square balusters, the treads and risers are manufactured wood with timber floor coverings over, note the nosing on the treads.