My solution (as a T) to this issue would be to sit on the first set of stairs in that stairwell watching both the spawn entrance to the stairwell and the backalley entrance to the hostie room. I find that when you are the last man standing, watching one spot is more dangerous than running(thunder feet).
For example, Office(any version) holding projector room alone can be done, but you better not sit still and give the opposition the advantage of knowing where you are or where simple breach/flash tactics can cause you the loss of your life and cargo(hosties)
AKGRN