Alternating tread stairs should only be used for loft conversion work where insufficient space is available to accommodate a conventional staircase and they should:

• Be in one or more straight flight.
• Provide access to only one habitable room plus bathroom or WC provided it is not the only WC in the dwelling.
• Be fitted with handrails on both sides.
• Contain treads which have slip-resistant surfaces.
• Have uniform steps with parallel nosing
• Have a minimum going of 220mm and a maximum rise of 220mm when measured over the wider part of the tread.
• Conform to the recommendations regarding maximum gap sizes for open riser stairs.