BS 8579:2020 lays down the various design requirements for balconies and terraces to ensure that the design of these spaces is efficient and compliant. Below are the various elements that designers need to take into consideration when designing balconies and terraces for buildings in the UK.
Every balcony must have a balustrade of a minimum of 1100 mm high, except where there is a step or anything climbable adjacent to the balustrade. In those cases, the balustrade height must be 700 mm above the height of the step.
Balconies should be designed with suitable thermal breaks in order to reduce heat loss and avoid condensation risk. The design should take into consideration the rotation that could occur from thermal breaks potentially having a low spring value.
All surfaces on which people walk and supporting layers on balconies should be designed and fixed appropriately so that they cannot easily be dislodged by wind, floatation or people walking on them. Such structures must be strong and sturdy enough to prevent them from becoming dislodged.
The surfaces of balconies must be of slip-resistant design. This can be achieved by selecting the right materials with textured surfaces.
Balconies and small terraces should be designed to include some kind of controlled drainage that prevents water ingress into the building, staining on the building, and nuisance to people or the landscaping below. Either edge drainage or pipe drainage could be employed to ensure that there is no water ingress.
For balconies that need to be installed using lifting equipment, the design should be such that it does not require persons to be working underneath the suspended load.
Balcony design should aim to reduce the number of persons working at height during installation wherever possible.
Balcony design should promote safe maintenance and should take into account the load arising from the replacement of façade glazing or cladding adjacent to the balcony.
Balcony designs must make provisions to prevent liquids or solids falling onto occupants of balconies below or into public areas. This can be managed by fitting a tray or impermeable layer into the soffit. Designers should assess the potential hazards of balconies above open pedestrian surfaces that do not have such protection and mitigate against injury.
Designers must ensure that every part of the design, including soffits and fascia cladding, has physical fixings to prevent parts from becoming dislodged by wind, maintenance work or other factors.
Projecting and partially projecting balconies should have a visible and durable label or sign with clear indications of the safe imposed load for which the balcony has been designed. This label should be prominently located and be as durable as the balcony itself. Further instructions and warnings on the unsuitable placement of heavy objects, such as paddling pools, large planters and hot tubs, on the balcony should also be mentioned here.
Fire safety checklist:
-not be composed of a material or designed such that they provide a medium for undue fire spread over the external envelope of the building;
-not propagate fire downwards, e.g. not produce falling brands or flaming/molten droplets or debris capable of initiating a fire below;
-be designed to minimise the risk of them becoming detached from the face of the building and presenting a hazard to people below, e.g. firefighters or the public;
-be designed to minimise the risk of prejudicing the stability of the building when undergoing large deformations resulting from fire exposure.
Eurocodes applicable to balcony and terrace design
Additionally, all balcony designs should also be in compliance with the standards mentioned in the following Eurocodes.
BS 1680, Barriers in and about buildings – Code of practice
BS EN 1990, Eurocode – Basis of structural design
BS EN 1991 (all parts), Eurocode 1 – Actions on structures
BS EN 1992 (all parts), Eurocode 2 – Design of concrete structures
BS EN 1993 (all parts), Eurocode 3 – Design of steel structures
BS EN 1994 (all parts), Eurocode 4 – Design of composite steel and concrete structures
BS EN 1995 (all parts), Eurocode 5 – Design of timber structures
BS EN 1999 (all parts), Eurocode 9 – Design of aluminium structures
BS EN 1090 (all parts), Execution of steel and aluminium structures
BS EN 16612, Glass in building – Determination of the lateral load resistance of glass panes by calculation