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Types of methods of fixing Balcony structures

How do you choose the correct method to fix a balcony to your structure and what are the advantages of each.

Cantilevered balconies:

These are balconies constructed in a manner so that the balcony protrudes from the face of the building without any visible supports other than the fixing to the face of the building. This type of balcony, while possessing the most aesthetic end result, will require the most designing in and will impose larger point loads on the building. This type of balcony cannot be added on but must be predesigned.

There are various ways to cantilever a balcony and in today's building another important factor that must be taken into account, particularly when using a steel balcony, is thermal conductivity. There must be a thermal "break" created and therefore if the ideal way to cantilever a balcony would be to have a steel member such as and RHS (rectangular hollow steel section) or similar be two thirds on the inside and leave a third protruding, this is now considered a bad solution by designers as it will negatively impact the thermal retainment of heat inside the building. To overcome this there are several companies offering "Thermal break" balcony joints in the market, or a break is created using two steel balcony connection plates with a HDPE (high-density polyethylene) sandwiched between them. Timber joists are an excellent solution and can be properly cantilevered as their thermal conductivity is very low.

Concrete is also a popular structure but again the thermal conductivity is a key issue in the use of this material.

Cantilevered balconies, being cantilevered members, will always have a bit of movement and "bounce". This can make the balcony users a bit uncomfortable sometimes. Cantilevered balconies are usually made to a maximum of 1500-1800mm depth. Beyond these depths the forces grow and require much more technical solutions. The smaller the depth the less movement you can expect.

Hung balconies

Another form of supporting the balcony structure is using stainless steel cables that fix to the walls and "hang" the balcony or balconies. The balcony sits perpendicular to the building and a steel cable fixes to the edge of the balcony and at forty five degrees is connected via a large plate to the building. The fixing at the wall makes maximum use of the bolt strength as it is using fifty percent "shear" and fifty percent "pull out" forces.

This is a very aesthetic solution but is not very common.

Stacked balconies or balconies on pillars

This is the most popular type of balcony structure, mainly because of the simplicity of implementation and the minimal load implications on the building. The balcony structure is supported using vertical pillars or posts. The weight of the balcony or balconies (if stacked on top of each other) is supported by these pillars and transferred to the ground. The size of these pillars is an element of the size, weight and number of balconies stacked on top.

This solution has an aesthetic compromise of seeing vertical pillars but is usually chosen for the structural simplicity and ease of implementation.