How would you build a step between rooms?

[endecotp]

Dear experts,

I’m insulating the floors in my ground floor flat; they will be floating OSB over insulation board over the original concrete slab.

The flat has two different levels with a step in between:

How would you reconstruct the step? (The old construction is a bodge.)

There are numerous pipes underneath. Below the pipes there is a mess of concrete and old stonework, hidden under lots of debris. The walls either side are 2x2 studwork.

I guess I should be making stringers, or something?

 

[ktuludays]

Timber framework screwed to the side studs

 

[endecotp]

Timber framework screwed to the side studs

Thanks. Would you plasterboard over the studs then screw the timbers for the step over the plasterboard, or would you screw the new timbers directly to the stud and cut the plasterboard to fit the steps?

 

[ktuludays]

For neatness, pb first.