Spiral Stairs?

Q: Are Spiral Stairs permitted as an interconnecting stair in Vertical Duplex Apartments?

A: Per BC Section 27-375(l). Spiral stairs may be used as an interconnecting stair in a Duplex Apartment. They should have at least 30" long treads. Per the below, spiral stairs do not count towards required exits. However, if the connected floor were a mezzanine and the stair was non-combustible, you might get it accepted as a means of egress under a Recon. You need to comply with the Duplex Apt Memo as well.

BC Section:
Spiral stairs may serve as access stairs between two floors or levels in accordance with the provisions of paragraph two of subdivision (i) of this section.

Such stairs may not serve as required exits, except that unenclosed spiral stairs when built of noncombustible materials and having a tread length of at least thirty inches may serve as exits from mezzanines or balconies having an occupant load not exceeding twenty-five persons.