Block walls are my second favorite type of walls for an exit shaft. Second to concrete because the block wall sits on the concrete floor and it will need to be firestopped at the top of the wall.
This is done after the stairs are installed. If it’s not done properly any breach which could mean fire and smoke could enter the exit stairs.
Here is your weak point ~ When the stair stringer runs against the floor slab, how is anyone going to install firestop in the top of wall joint behind the stair stringer?
If you deal with this, what is your solution?
Tomorrow I will tell you why I hate gypsum walls for exit stair enclosure. In the meantime, let me know what you think.