Different balcony structures have different drainage requirements. Concrete balconies, for example, tend to be treated like a flat roof and are normally finished with a waterproof membrane, drainage outlet or overflow pipe. When using a metal balcony structure, which will often have a permeable deck, drainage options are interrelated to the use of fascias and soffits.
Fascia boards ensure a neat finish to a residential balcony and protect exposed edges from weathering. Soffit boards are fitted to the underside of the fascia to complete the clean-edged look and provide a weatherproofing seal. Typically, balcony fascias and soffits are manufactured from polyester powder coated aluminium for a durable, low maintenance solution.
Typical Soffit Options
PPC aluminium sheet:
This is the most popular option for balcony soffits. Usually, the fixings are concealed, and the soffit is broken up into panels 400mm wide with neat butt joints, although this can vary. The benefit of this approach is that there is no concentration of water and however long a balcony is doesnt make it more likely to have water drainage and ponding issues. Powder coated (PPC) Aluminium soffits provide a Class A2 s1 d0 European Fire rating meaning they are classified as non combustible. This is a mandatory requirement in residential buildings taller than 11m in the UK and the June 2022 recommendations of the Approved Document Part B also suggests that balconies should use ‘Non Perforate, Non Combustible Soffits’ – a recommendation we fully support.
Open soffit/Drained through balconies:
This is a cost saving option which is not as neat in appearance and is only suitable for free draining balconies, Balconies where water is drained through are recommended against in BS8579:2020, the balcony standard for resident safety and nuisance reasons. With open soffits, the balcony structure can be left as mill finish, or powder coated in a darker colour to make it less noticeable.
Some clients choose to clad the underside of the balcony with decking to match the top surface. This would normally be in a free draining situation where water falls between the deck boards. This used to be much more common than it is now as historically this meant that balconies would be glad with combustible materials. This is now banned in the UK after the revisions to AD B following the Grenfell tragedy.
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