Unprotected stairways in small buildings

An unprotected stairway may be used as an escape stairway in a small building provided that – (a) the building is of Purpose Group 3 or 4 and is not used for bar or restaurant purposes; (b) the building is designed for single occupancy; (c) the building comprises not more than a basement, ground and first storey; (d) the floor area of any storey is not more than 90 m2; (e) the stair does not connect more than two storeys; and (f) the stair discharges not more than 3 m from a final exit.