A new British Standard is supplying guidance on balcony and terrace design at time when such features are becoming more and more common. This blog post explains why the standard was written, who by, and what it contains.
There’s been a general consensus for some time that the UK construction sector could make use of some authoritative guidance on how to design balconies and terraces. On the one hand, these features are becoming more common because of the increasing number of medium- and high-rise residential developments being built with some outdoor amenity space. On the other hand, UK construction industry opinion seems frequently to be divided as to how best to design balconies. The need for a British Standard was clear.
To that end, BSI convened a panel of experts to draft the standard. It included architects, structural engineers, and fire safety, drainage and accessibility experts. The result is BS 8579:2020 Guide to the design of balconies and terraces, which has been published this month.
The design of balconies and terraces
BS 8579 gives guidance on the design of balconies and terraces and their component parts. Such balconies and terraces can be at any height above lowest ground level, unless stated in the text.
The standard applies to terraces and projecting, inset, open, enclosed and juliet balconies. Juliet balconies are defined as a balcony formed by adding an external guarding to full-height openable doors without an associated external floor. The standard covers the guarding of juliet balconies only. Nor is the standard intended to cover internal balconies, such as within a building atrium, but relevant guidance in the standard can be used in the absence of guidance specific to such balconies.
The standard also notes that balconies and terraces are important because they provide building occupants with an amenity, but also because they’re highly influential to forming the character of buildings. As such, balcony and terrace design has two aspects: the aesthetic and the functional. The standard goes on to say that because the former is so subjective and wide-ranging, the standard doesn’t deal with aesthetics, but instead sticks to the functional elements of design, with the aim of setting a new benchmark for quality and functionality in the design of balconies and terraces.
After setting out definitions, the standard covers general principles. Balconies and terraces, it states, should be designed to provide amenity to building users and should be an appropriate size for their intended use.
The next section looks at the enclosure of balconies. Balconies can be open, wholly or partly covered by another balcony or roof above, or can be enclosed by weather screens and a roof or balcony above thus creating an enclosed balcony. Design factors for consideration include the effects of wind on any opening components; the potential for water penetration; the effects of enclosure on fire and smoke and the spread of flames; the effects on acoustics into and between apartments, and cleaning and maintenance considerations.
The following section looks at how balconies are arranged. This is followed by a full section dedicated to wind effects – which can be significant to a balcony’s occupants, objects placed on the balcony and to the balcony itself. The standard discusses wind mitigation measures. The next section looks at the service life of balconies (which should be the same as that of the primary structure of the building).
There then follows a section on inclusive design, so that balconies and terraces are designed to provide equal utility and enjoyment for all users. Considerations include door and threshold design as well as surfaces, sightlines and dimensions.
The next section deals with structural and mechanical stability and integrity; and the following one with safety. This includes the safety of people on balconies – including loading, and fall and slip prevention – and the safety of persons below the balcony, as well as constructing, cleaning, maintaining and dismantling balconies.
The next major section looks at fire performance of balconies. This is succeeded by a section on thermal considerations – noting that balconies and terraces incur heat losses and gains that impact energy consumption, condensation risk and the comfort of building users.
The next section is on ventilation outlets near balconies. This is followed by a large section on weathering and hydraulic design – in other words, how rainwater affects a balcony and its surrounds. The drainage of balconies and large and small terraces is considered, as is preventing water ingress to the building, and issues such as assessing the volume of rainfall on balconies.
The two final sections deal with security and acoustic design. An annex then illustrates a possible terrace waterproofing arrangement. This concludes this comprehensive new standard, making it a very useful document for anyone with a professional interest in balcony and terrace design.
Learn more about BS 8579:2020 or buy now