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B.4 Balcony Type Recommendations
Through this analysis and comparison it is evident that continuous slab balconies are the most cost effective and simplest to construct. At the same time they provide the poorest score for thermal performance, resilience and occupant comfort of all balcony types. As the structural connection between the balcony and the building’s primary structure is minimized the amount of thermal bridging is reduced. Each of the eight connection details have their own individual characteristics and associated strengths and weaknesses. Decisions on which connection detail to use should be made using a holistic understanding of each detail.
By our assessment and understanding of performance requirements, balcony types 1, 2, 4, 7 and 8 do not qualify as robust future proof systems.
Balcony types 1, 2 and 4 are only able to meet required TEDI targets at the expense of the other dependent building systems which are required to compensate for their inefficiency. With increasing performance target requirements, using these balcony types and this compensating approach is only viable to a certain point. The R-value of a wall can only be increased, or the window to wall ratio can only be decreased to a certain point to compensate for thermal bridging before it becomes commercially or economically inefficient. Options 7 and 8 have the potential to perform well on low to mid-rise buildings but are not a feasible solution in high rise construction. Since they rely on a self supported structure, independent of the building this becomes increasingly challenging the higher the building becomes. Option 3, 5 and 6 on the other hand allow for the highest performance targets and a more balanced approach for improving the overall building performance. These balcony types can be used in conjunction with incremental improvements to other building components and systems to achieve higher performance targets rather than relying on the other components to compensate for poor performance related to thermal bridging.
Option 6 scores the highest as it allows for the distribution of structural loads back to the building to more but smaller connections. This reduction in connection size equates to less thermal bridging allowing this balcony type to achieve a slightly higher thermal performance, and resilience and occupant comfort score.
Between these three recommended balcony types, cost, structural constraints, designer and contractor familiarity and architectural expression of the balcony can inform which type is best suited for an individual project. In Europe, the extensive use of proprietary systems has driven the price down and allowed designers and contractors to become more familiar with the systems. Once these proprietary systems become more common North America, they will likely become the favored detail type due to their compatibility with existing construction techniques and detailing as is evidenced in the European market.
