Code of practice for design and construction of wood stairs for houses
1992 Edition

The code recommends using timber species that are suitable for structural use as defined in the relevant timber classification standard. For stair treads, the timber should have a minimum density of 600 kg/m³ to assure strength and durability. Timber must be treated following preservation guidelines to enhance longevity. Commonly recommended species include Teak, Sal (Shorea robusta), Deodar, Shisham (Dalbergia sissoo), and Mahogany, complying with fire safety provisions as per related fire safety standards.

As per the code, the minimum tread width should be 270 mm, with the nosing projecting at least 15 mm but not exceeding the thickness of the tread. The nosing should have a rounded edge with a radius not greater than 100 mm for safety. Tread thickness must be at least 32 mm for stairs up to 1.2 meters wide. Riser thickness should be a minimum of 16 mm for solid wood and 9 mm for plywood. Additionally, the front part of the tread containing the nosing must be at least 90 mm wide to ensure structural integrity and user comfort.

The code specifies that newels must be installed at every change in handrail direction, with outer newels having a minimum cross-sectional area of 6000 mm² and wall newels a minimum of 2500 mm². Steps should be housed into newels by a depth of no less than 15 mm. Newels require mortise and draw-boring for string attachment and mortising with dowels to secure handrails. Handrails must be a minimum of 100 mm wide at the top, include curves or wreaths at flight direction changes for safety, and the space between the handrail and string must be filled with balustrades or appropriate infill. Wall-side handrails should be rigidly fixed to the wall without balustrades attached to them.

The stairs must use solid timber for treads and strings, with joints such as tongued and grooved or mortice and tenon permitted. Surfaces of joints prone to gap formation should be treated with preservatives or sealed with compounds like white lead to prevent moisture intrusion. Each timber element should have a minimum finished width of 80 mm, with the tread front (nosing) at least 90 mm wide. Fasteners must comply with the relevant structural timber design standards, be corrosion-resistant, and compatible with treated timber to ensure durability and structural soundness.

Fire safety is addressed by requiring compliance with dedicated fire safety standards, including codes covering construction details and exposure hazards. The wooden stairs should incorporate fire-retardant treatments, non-combustible nosings, and fire-resistant enclosures as specified in the referenced fire safety codes. While the code itself does not detail fire safety designs, adherence to these related standards ensures the wooden stairs meet fire resistance and precautionary requirements to minimize fire risks.