Tristan Parsons, Managing Director of leading UK balcony specialist, Sapphire Balconies, provides some answers on designing and manufacturing balconies using offsite processes.
Q: What is the biggest challenge with putting balconies on buildings using offsite?
Transferring the structural loads into the building. On a traditional RC frame building the large cantilever forces from the balcony are taken by the RC floor slab. On other frames consideration must be taken at the design stage to ensure the load is properly managed.
Q: Which balcony materials should I consider?
Aluminium is much lighter than other materials so reduces the forces going back into the structure, making it far better suited to offsite processes.
Q: Should balconies be installed in the factory or on-site?
We recommend installing balconies to the building on-site, avoiding double handling, allowing larger building modules to be transported, and reducing lorry movements as balconies can usually be stacked on a trailer.
Q: Is there a risk of bouncy balconies and how is this best avoided on offsite schemes?
Firstly, early design engagement. The risk of bouncy balconies is higher than with RC frames, so it’s important to engage early on to ensure that the necessary structure is designed in to take the balcony loads.
Secondly, ensure structural brief includes deflection study. It is extremely important to ensure that the structural engineer designs the supporting elements not only to resist the loads but also carefully assesses the deflection that will result from movement within the structure
Finally, balcony projection – especially with offsite – works better to keep the balcony projection down where possible (e.g. a 6x1.5m balcony is better than a 4x2m balcony)