An inset balcony is a balcony which is recessed into the façade or roof of a building. Traditionally this would be a balcony which would have three sides enclosed with the building leaving one side of the balcony guarded with a balustrade. More commonly however, particularly in London inset balconies are used as architectural statements and often have two sides formed by the building and two sides with a balustrade forming a guarding.
Traditionally, the base of an inset balcony would have been formed by the concrete slab, however we’ve experienced the continuous struggle with balustrade fixings hitting rebar, making balustrades very slow to install and delaying programmes. The significant amount of damage which can happen as scaffold is struck around finished balconies and as other trades finish is also a continuous challenge with concrete balconies. Accidental damage is frequent on a busy building site as so many trades interface to finish concrete balconies and their completion is often staggered. We initially moved into offsite balcony manufacture with steel balconies and now Glide-On™ balconies realising the benefits these offer over concrete when it comes to inset balconies.
When it comes it follows the same process as with our projecting glide on system. Anchors are cast in, stubs attached, and later arms. Then the balcony simply glides onto the arms.
The Key benefits are below:
There are several key points to consider when comparing concrete inset balconies with other systems and managing maintaining compliance with the latest fire regulations. The NHBC recently flagged most waterproofing systems do not achieve higher than Class B which is banned above 18m. According to our research, 62% of balcony fires since 2017 have occurred on concrete balconies and many decking support systems do not meet the Class A2 requirements. Using Glide-On™ aluminium balconies requires minimal penetrations of the façade, a StubGuard™ can be used to maintain cavity barrier integrity.
Balconies require positive drainage which means water is congregated and brought towards the building. Of course, concrete balconies cannot be drained through the concrete limiting drainage options. As water is collected above the surface of the balcony, achieving a 150mm splash back and 75mm minimum distance from water collection to the threshold often means a deep balcony is required. It is key to consider the weight added by a deep balcony, the need to have an overflow to stop flooding and that all drainage types above 18m need to be non-combustible
Balconies need isolating on three sides in most inset balcony scenarios. Even when inset, Glide-On™ balconies only require thermal isolation at the point the connections penetrate the façade. For example, the installation shown on the right would require 10.4m of thermal break if built in concrete. Whereas, using Glide-On™ meant there were only 4 penetrations reducing the total area requiring thermal breaks by approximately 89%. Glide-On™ balconies can also help achieve improved SAP rating.
Due to the fact that concrete balconies are cast in-situ soffits need to be fitted afterwards. This will typically require at least a two-person team working from access equipment below to fix bracketry, then soffits. Prefinished balconies are installed with soffits already installed, saving time, money, and trades involved. Where a soffit would take two people at least 2 hours to fit on-site, meaning 4 man hours, ours would take only 15 minuets in the factory and zero man hours on-site.
Balconies usually involve a thermal break supplier, waterproofing company, RC frame contractor, decking supplier, balustrade manufacturer, and soffit installers. Glide-On™ balconies on the other hand, involve just the RC frame company, the balcony manufacturer, and the balcony installers. Glide-On™ balconies can be fixed to thin slabs, e.g. 205, or slabs with minimal floor coverings. Such scenarios can be difficult to achieve in concrete, taking into consideration waterproofing on top of the slab.
Timescales and cost
Due to the programme being dependant on many trades working on balconies getting sequencing right, the knock on affects one trade can have makes the programme very vulnerable to delays. Concrete balconies are dependent on scaffolding to load out and finish balconies meaning the top balconies must be finished before scaffolding can be struck. These areas are also often the last to have the façade finished around them meaning that scaffolding is often in place longer as it can’t be struck until the balconies are finished. Items including deck support systems, soffits support rails, waterproofing membranes, and base fixing channels for balustrades are not required with a Glide-On™ balcony. Coupled with significantly increased area of thermal break requirements these materials will often make an inset concrete balcony more expensive. With Glide-On™ balconies, soffits are fitted during production which is a one-person job and can be fitted in a fraction of the time it takes to fit them onsite.
Integrating brick slips and columns
Ensuring inset balconies fit with the building design and façade is essential. Glide-On™ inset balconies are available with brick slips to maintain the continuity of the façade and are compatible with the use of columns