It would seem that stairs in tenancies are now the de-rigour must have. From a few years ago when they were reasonably rare, and very costly, we now find that almost all multi floor fitouts are putting in stairs to aid connection between teams. Typically made from steel and fabricated on site (because they must come up in the good lift) a well designed staircase doesn’t need to cost a fortune. But, don’t forget what goes in must come out. Ensure you provision for the cost of removal when factoring in for the make good. You don’t want a hole in the books as well as the floor.