[tetromino_]

Regardless of whether the building is concrete or wood, it will have plastic: interior decorations, exterior cladding or siding, fittings, insulation, polymerized paint on the walls and ceilings, synthetic carpeting on the floor, furniture and personal property... You won't die from spreading flames, flames spread slowly; instead, you will very quickly die from toxic smoke from burning plastic. The toxic smoke which will spread equally well in a concrete or wooden apartment building.

[jetzzz]

You can separate stairwell and elevator hall/apartment hallway with an open balcony like they do in some countries. This way smoke from the rest of the building can't get to the stairwell. This is called smokeproof enclosure.