Railing/Balustrade types, usages and legal requirements
What height is required?
For internal railings or
balustrades that are inside a single family dwelling the height required is 0.9m from "datum" (the height you can stand on) to the top of the handrail. This is the same for stairs in these area as well.
For external
balcony or terrace areas the required height is 1.1m from datum to top of handrail.
What loadings are these
railings/
balustrades meant to withstand and how are these applied, tested or calculated?
The loads are expressed in kN/m (kilo Newton meter) in simple terms this is a quantity very similar to 100Kg (220lb) of pressure per meter length. If for example it is stated that there is 1.0kN/m it will be appx the equivalent of one person weighing 100kg putting their full weight on one meter length.
There are two basic loads that are required to be met; (a) Loading on the handrail and (b) loading on the infill. The loading on the handrail is called a uniformly distributed line load (basically meaning that the load needs to be calculated in a fashion that allows for even distribution of the pressure along the complete length of the element, as opposed to the sum of the load applied to one point). The load on the infill, be it glass, metal or other, is tested and calculated in two separate ways; a distributed load and a point load. This means the infill of the railing, balustrade or barrier must be able to stand an evenly distributed pressure as well as a concentrated pressure on a small point.
The loads are tested or calculated whereby the maximum deflection under pressure must not exceed 25mm.
You can divide regulations into these basic areas;
A)Domestic & residential (single family home) internal stairs/landings etc in which case the handrail pressure must be able to take 0.36kN/m For external balconies & also in light office areas non susceptible to overcrowding this is doubled to 0.74 kN/m (this can be compared to having one averagely weighing person 75kg applying the full force of their body on every meter of the balcony)
B)Public areas such as retail areas, bars & restaurants the handrail pressure must be able to take 1.5 kN/m. This is doubled to a dramatic 3.0 kN/m in areas such as malls, discotheques and areas susceptible to overcrowding.
As the point load is the more severe, the loadings on the infill panels are as follows:
A)Domestic & residential (single family home) internal stairs/landings etc Point load: 0.25kN/m For external balconies & also in light office areas non susceptible to overcrowding 0.5kN/m.
B)On all public areas such as retail areas, malls, discotheques, areas susceptible to overcrowding, bars & restaurants the point load must be able to take 1.5kN/m.
When dealing with glass barrier one more element must be taken into account and that is impact resistance of the glass. A minimum of 10mm glass should be employed in balcony areas that are wider than 1.5m.
