Balustrades, Handrails & Stairs
A balustrade is a vertical upstand which protects users of a building next to a vertical displacement between horizontal building surfaces or on the side of a stair.
In Australia Parts 3.9.1 and 3.9.2, Volume 2 and Australian Standard 1170.1 are written to ensure building that enables people to move safely between different levels of the building using stairs or ramps.
To prevent people from falling, a continuous balustrade or barrier must be provided alongside any stairway or ramp, any floor, corridor, hallway, balcony, verandah, mezzanine or path of access to a building if it is not bounded by a wall or any level more than 1 m above adjoining floor or finished ground level.
It is important to note that the measurement of the height of the balustrade or barrier is from the finished floor surface. Finishes such as ceramic tiles and even carpet can make a significant difference to the finished floor height.
The height of a Balustrade or Barrier must not be less than:
- 1m above the floor of any access path, balcony, landing where it is not bounded by a wall and its level above the surface is 1m or more than 4m where a person is able to fall through an open window
- 865mm above the floor of a landing to a stair or ramp where the balustrade or other barrier is provided along the inside edge of the landing and is not more than 500mm long.>
A transition zone may be incorporated where the balustrade or barrier height changes from 865mm on the stair flight or ramp to 1m at the landing.
To comply with requirements of Acceptable Construction Practice, stairs should not have:
- more than 18 risers in a flight of steps to ensure that people negotiate a limited number of steps before a landing is installed so they can rest
- more than 3 winders in a ¼ landing where the going of the winders to either ¼ or ½ landings may differ from the remainder of the flight however they must be consistent with the landing and not varied individually:
- a riser opening greater than 125mm
- a going less than 240mm for a straight flight of steps.
The maximum gradient of a ramp should not exceed 1:8 and the floor surface must be non-slip.
Construction and Design
Balustrades or barriers should be constructed such that a person cannot fall over or through them while at the same time restricting a child crawling through them. Openings in balustrades or barriers must be constructed so that any opening does not permit a 125mm sphere to pass through it where for stairs this space is tested above the nosing line.
A barrier should be strong enough to resist collapse should a person fall or lean against it. A balustrade or barrier must be designed to take loading forces in accordance with AS 1170.1 which requires that a balustrade or barrier should be structurally adequate to withstand a point load of 0.6kN and an evenly distributed load of 0.4kN applied inward, outward, or downward on the handrail.
These design loads are intended to ensure that the barrier is rigid enough to withstand a person falling against it without collapsing (point load) and suitably rigid and strong enough not to collapse should people lean against the barrier (distributed load). The handrail must also be able to withstand wind loads, particularly where a solid panel is used externally.
In weather or moisture exposed applications, handrails, posts, newels, balusters and infill should either be naturally durable Class1 or Class2 timber species such as Blackbutt, Spotted Gum, Ironbark, Jarrah, Merbau, or Kwila with any sapwood present treated to H3 standard. Alternatively, preservative treated softwood should be treated to H3 standard or higher and should comply with AS 1604. Ideally, the timber should be free of any major strength reducing features and be straight.
All metal connectors including nails, screws, bolts and brackets should be a minimum of hot dipped galvanised or for screws, Class 3 corrosion resistance as per AS3566. For coastal environments subject to airborne salts deposition, stainless steel or equivalent corrosion resistance metal connections should be used.
Nail holes should be stopped with exterior grade wood filler. Dirt or any loose material should be removed prior to coating. All timber-to-timber interfaces for all joints should have a seal coating of preservative formulation and all surfaces, ends and joints should be primed prior to assembly with a quality solvent based alkaloid primer or stain in accordance with manufacturer's recommendations. Two final top coats of exterior paint or stain should then be applied in accordance with manufacturer's recommendations.
For floors, more than 4m above ground, any horizontal elements within the balustrade or barrier between 150mm and 760mm above the floor must not facilitate climbing. To prevent this ideally, the balustrade should have vertical members spaced no more than the maximum opening or be a solid panel barrier.
Handrail and Barrier heights must not be less than:
- 1m above the floor access path, balcony or landing
- 865mm above the nosing of the stair
- A transition zone may be incorporated where the balustrade or barrier height changes from 865mm on the stair flight or ramp to 1m at the landing
- Posts are to be spaced maximally at 1.8m
- Wire must be stainless steel with a minimum diameter of 3.2mm
- Maximum wire spacing is 100mm
- Intermediate droppers are to be fitted at a maximum 900mm between posts and secured top and bottom
- Tensioners are to be placed on each strand of wire at each change of direction of 30 degrees or more
- A solid handrail is required of steel tubing with a minimum diameter of 40mm or timber as per the Timber framing Code AS 1684.2 1999.