Why is balustrading strength important?
Whilst in some instances balustrading may be installed for decorative, demarcation or privacy purposes, in the main, a balustrade is designed and installed with the primary purpose being to protect persons from falling from a height. Therefore, careful consideration must be given to the structural strength of balustrading and barriers, or simply put, how strong they must be to be safe.
Regardless of whether your balustrade is manufactured from timber, glass, metal, stainless steel, aluminium, or any other material, the same load requirements need to be met.
Using the wrong materials or suppliers for your balustrade can prove very costly in the long run. Not only can the product deteriorate after a very short time, but Building Control can also insist you remove the faulty balustrade and replace it, even many years down the line when you may come to sell the property! This usually ends up being at your expense as by then, the “cowboy” supplier has disappeared.
What is a Balustrade load, and how is balustrading strength measured?
A load on a balustrade can be defined as a force, weight or pressure applied to the balustrade by something or someone. When designing balustrades, it is essential to consider, in accordance with BS6180:2011, both the imposed load requirements for the location of the balustrade and the types of loads that are applied.
The horizontal uniformly distributed line load (Horizontal UDL) is one of the most critical loads to consider for a balustrade protecting a fall. A fall or drop requiring a balustrade is defined as:
- In dwellings – when there is a drop of more than 600mm.
- For buildings other than dwellings and for common access areas for buildings that contain flats – when there are two or more risers.
The force (or strength) of the load is measured in kilonewtons per metre. (One kilonewton, 1 kN, is equivalent to 102.0 kgf, or about 100 kg of load under Earth’s gravity.)
What loadings or force must a balustrade meet to pass regulations?
There are four core uniformly distributed line load categories applicable for balustrades or barriers. This load or loading refers to the force applied to the balustrade per linear metre of the balustrade at 1100mm above finished floor level:
- 36kN/m applies to all areas within or serving exclusively one single-family dwelling, including stairs, landings, etc. but excluding external balconies and edges of roofs.
- 74kN/m Other residential, i.e. houses of multiple occupancy and balconies, including Juliette balconies and edges of roofs in single-family dwellings and areas not susceptible to overcrowding in office and institutional buildings, including stairs, walkways and balconies.
- 5kN/m for areas where people might congregate and public walkways and pavements less than 3m wide which protect a drop.
- 3kN/m. Footways or pavements greater than 3m wide and public areas such as theatres, bars, shopping malls and other areas susceptible to overcrowding.
However, please refer to the entire table below to ensure the correct categorisation of your project.
NOTE: the horizontal uniformly distributed line load should be assumed to act at the height of 1100mm above the floor or pitch line, irrespective of the height of the actual balustrade.
The other load types to be considered under the British Standard are:
- The uniformly distributed load to the infill panel which is applied below the level of the handrail and is measured as a value over an area of 1 square metre.
- The point load which is applied to the most onerous point of the infill over a small area of 5cm x 5cm.
- The performance of the barrier or balustrades under impact should also be considered.
- Wind loads – ensure the balustrade is designed to comply with the maximum allowable stress.
As you can see, the loads are both incidental, static impact and dynamic impact, and your balustrade supplier can discuss your specific project requirements.
How does a balustrade pass a load test – the 25mm deflection rule
Balustrades for the protection of people should be of adequate strength and stiffness to sustain the applied loads given in Table 1 below, with the total horizontal deflection of the barrier at any point from its original unloaded position should not exceed the deflection limits determined from the relevant structural design code (where applicable) for the material used, or 25 mm, whichever is the smaller.
In addition, a balustrade should not possess sufficient flexibility to alarm building users when subject to everyday use. Therefore, for serviceability considerations, the limiting condition for
Where the infill of a balustrade is subjected to imposed loads given in Table 1, or if appropriate, other calculated design loads, the displacement of any point of the barrier should not exceed L/65 or 25 mm, whichever is the smaller where L is the given in 8.3, 8.4 or defined in 8.5 of BS6180:2011.
BS6180 Balustrade loads – In conclusion
I’m sure you now understand that ensuring your balustrade meets the required loading and strength regulations is a far more significant consideration than just “ticking a regulatory box”. It directly impacts the long term safety and the resale value of your property.
The full table detailing the loads (or forces) that balustrades or balustrading need to meet, according to BS 6180:2011:
|BS6180 Balustrade & Barrier Loading Requirements||White Metal Quick Ref||Horizontal uniformly distributed line load (kN/m)||Uniformly distributed load applied to the infill (kN/m2)||A point load applied to part of the infill (kN)|
|Domestic and residential activities||i) All areas within or serving exclusively one single family dwelling including stairs, landings, etc. but excluding external balconies and edges of roofs||1||0.36||0.5||0.25|
|ii) Other residential, i.e. houses of multiple occupancy and balconies, including Juliette balconies and edges of roofs in single family dwellings||2||0.74||1||.5|
|Offices and work areas not included elsewhere, including storage areas||iii) Light access stairs and gangways not more than 600 mm wide||3||0.22||-||-|
|iv) Light pedestrian traffic routes in industrial and storage buildings except designated escape routes||4||0.36||0.5||0.25|
|(v) Areas not susceptile to overcrowding in office and institutional buildings, also industrial and storage buildings except as given above||5||0.74||1||0.5|
|Areas where people might congregate||(vi) Areas having fixed seating within 530 mm of the barrier, balustrade or parapet||6||1.5||1.5||1.5|
|Areas with tables or fixed seatings||vii) Restaurants and bars||7||1.5||1.5||1.5|
|Areas without obstacles for moving people and not susceptible to overcrowding||viii) Stairs, landings, corridors, ramps||8||0.74||1||0.5|
|ix) External balconies including Juliette balconies and edges of roofs. Footways and pavements within building curtilage adjacent to basement/sunken areas||9||0.74||1||0.5|
|Areas susceptible to overcrowding||x) Footways or pavements less than 3 m wide adjacent to sunken areas||10||1.5||1.5||1.5|
|xi) Theatres, cinemas, discotheques, bars, auditoria, shopping malls, assembly areas, studio. Footways or pavements greater than 3 m wide adjacent to sunken areas.||11||3||1.5||1.5|
|(xii) Grandstands and stadia||12||A|
|Retail areas||(xiii) All retail areas including public areas of banks/building societies or betting shops||13||1.5||1.5||1.5|
|Vehicular||xiv) Pedestrian areas in car parks, including stairs, landings, ramps, edges or internal floors, footways, edges of roofs||14||1.5||1.5||1.5|
|(xv) Horizontal loads imposed by vehicles B)||15||B|
|A) See requirements of the appropriate certifying authority.|
|B) See Annex A. of BS6180|