Following a number of notable balcony fires and the Hackitt report, Approved Document B was changed in November 2018 (and also as amended in December 2019 and April 2019) in that balconies must now be made from materials of limited combustibility.   The MHCLG followed this up with advice that culminated in January 2020, advising building owners that the removal and replacement of any combustible material used in balcony construction is the clearest way to prevent external fire spread from balconies.  This creates not only a challenge for Architects and specifiers to create designs to meet these new technical requirements, but also to achieve the appearance and feel that is expected in a space that is often an extension of the home.

There are key decisions that need to be made in the selection of the appropriate finish, these are set out in the following section.

Free-draining is used to describe the design where rain falling on the balcony can fall between the decking boards.  Free draining balconies need to have a gap between the decking for the water to drain through.  Free draining balconies don’t usually have soffits, so this can reduce the cost, but it is important to consider what the decking will look like from underneath as this will be readily visible.  Neat bearers and boards that are attractive from the underside also is important.  Its also important there aren’t too many small crevices that birds or insects can nest in.

Drained balconies can be either surface drained or via a lower drainage layer beneath the decking, this can be either via a soffit that catches the water or, an impermeable structure to the balcony itself (such as precast concrete).  With drained balconies, it is important to ensure that the waterproofing extends up the facade at least 150mm from the drainage layer (at least 75mm at doorways).  The selection of the waterproofing must be carefully checked against the requirements of Part B of the building regulations.

Whilst achieving the right appearance is important, it is also important to choose a balcony finish that fulfils the performance requirements:

• FIRE: Must be A1 or A2-s1 d0 as classified by EN 13501. Note that this applies to EVERY component of the system (i.e including any pedestals, or fixing clips).
• STRENGTH: Must have the required strength for the application. The strength is tested via the application of a distributed load, but also a point load at the support centres that you wish to use.  The use class of the balcony or terrace will determine the distributed load and point loads that need to be achieved.
• SLIP POTENTIAL: Slip potential must be considered and be suitable for the application. PTV vales are used to assess this.  Refer to the HSE website for more guidance on this.
• THERMAL EXPANSION: The material that the decking is made from will determine the thermal expansion. Aluminium has a coefficient of thermal expansion of 24×10^-6m/mK.  This means that for example a 3metre section of aluminium will get around 3mm longer at 40^°C than it is at 0^°  If this is not accounted for in the fixing design, the fixings can break.  Calcium silicate composites can have a coefficient of thermal expansion of 13×10^-6m/m.  So, expansion gaps can be smaller.
• SCRATCH RESISTANCE: It is common for balconies and terraces to have furniture placed on them. Ensure that scratches don’t become a problem during construction or during the lifecycle of the structure.
• WEATHERING PERFORMANCE: Make sure that any materials specified have had the material and coating tested for longevity. This can be carried out by accelerated weathering testing.  Where the material is subjected to a cycle of UV, freezing and thawing actions to simulate an appropriate number of years.
• LIGHTNING PROTECTION: Any conductive elements must be considered as part of the risk assessment conducted for lightning protection in accordance with BS EN 62305.
• HEAT BUILD-UP: Especially if the balcony or terrace will be accessed barefoot, it must be considered that the surface should not build-up too much heat such that it could cause burning. Metal surfaces generally heat up more in the sun than other materials.
• NOISE: The surface must not generate excessive noise from wind, rain and hail.

Conclusion

There are a range of materials available, by considering the key performance factors, it the best material for the application can be selected, and will perform for the long term.

It’s not just cladding

Due to recent focus on cladding, we thought it timely to write to you to discuss that the issue is not just about cladding, balconies are as much of a concern yet don’t seem to get as much coverage, and the problem can be more difficult to solve because of the limited design solutions available.

Balconies are an essential part of high-rise living, especially during our current period of lock-down. They provide an essential space for fresh air, reflection, a quiet espresso in the cool morning air, and often, smoking!  Architecturally, balconies frequently define the drama of the façade of a residential building and invite the outside in.

The industry has responded to this challenge with a range of aluminium decking systems and until now, the choice has been between one type of aluminium or another.

“We had experience of developing composites for non-combustible cladding, and when we saw the requirement for decking, we set about trialling the same technology for decking boards”.

“We had a number changes to make to the production ingredients, adding higher strength fibre and eliminating water-based colourants, each time testing the end result. We had to consider properties that we hadn’t had to before, such as slip resistance”.

“We are really pleased with the results, we have achieved a non-combustible decking product that would be at home at home.”

Following a number of notable fires and the Hackitt report, Approved Document B was changed in November 2018 (and also as amended in December 2019 and April 2019) in a number of respects including that balconies must now be made from materials “of limited combustibility”.

The MHCLG followed this up with advice that culminated in January 2020, advising building owners that “the removal and replacement of any combustible material used in balcony construction is the clearest way to prevent external fire spread from balconies”.

This creates not only a challenge for Architects and specifiers to create designs to meet these new technical requirements, but also to achieve the appearance and feel that is expected in a space that is often an extension of the home.

You are of course aware of a range of aluminium decking systems.

However, a team of Engineers at Blazeboard have applied their combined expertise in building engineering and composite materials to develop a product that achieves the requirements of Approved Document B as well as the MHCLG guidance, whilst having the appearance and tactile properties that are more appropriate for residential applications.

The appearance of Blazeboard is based on the colour of driftwood, because it doesn’t create watermarks like wood, and emulates the silvery sheen that natural hardwood takes on after a couple of years in sunshine.

Blazeboard also has the tactile feel of hardwood that can be comfortably walked on whilst barefoot

Our Engineers can work with you to create a balcony design that is rigid and robust, yet won’t suffer from the thermal expansion issues of aluminium systems. If you would like us to look at a project with you, please let us know, or even just request a copy of our Balcony Finish Selection Guide.

Sincerely
Spencer Allen
Commercial Director
Blazeboard Ltd

The team at Blazeboard is very experienced. They have worked with wood to create attractive designs for flooring and balcony decking. We applied our engineering experience of re-inventing construction materials to create Blazeboard which provides the visual and feel appeal of wood, whilst achieving the non-combustibility requirements demanded by the building regulations.

They are suitable for use in:

• Balconies at any height
• Roof terraces
• Walkways and bridges
• Fire Escape routes
• Building cladding

The advantages are many such as the following:

• “Cut, fix and set out the 145mm wide boards just like wood”
• “Through-coloured in a range of colours”
• “fire classification of A2-s1, d0 or A1 when classified in accordance with BS EN 13501:2007+A1:2009.”
• Quality Materials
• 15 Year Warranty
• Unique Technology
• Highly Experienced Team