Cherrywood T3, T4 and T5

Cherrywood T3, T4 and T5 is a significant residential development in Dublin comprising apartment buildings and duplex homes designed to provide high-quality modern living spaces. Arc Engineering was appointed by B&C Contractors to design, manufacture and install a complex package of cantilevered balconies across the development.

The project consisted of 59 balconies in total, including 52 balconies to the T5 apartment and duplex blocks and a further 7 balconies to the T3 duplex development. The works incorporated Schöck cast-in thermal anchors, hot-dip galvanised steel support stubs, galvanised steel balcony structures, aluminium decking systems, vertical bar balustrades with integrated glass windbreaks and bespoke powder-coated aluminium soffits incorporating concealed rainwater management.

While the apartment balconies were challenging in their own right, the duplex balconies presented the most significant engineering and coordination challenges. Unlike typical cantilevered balconies, which are generally around 1.6 metres deep, the Cherrywood duplex balconies were required to provide approximately 10m² of usable external space. This increased the balcony depth to approximately 2.6 metres, substantially increasing loading, structural demands and interface requirements.

From the outset, Arc Engineering worked closely with the client, architects, structural engineers and specialist suppliers to assess the implications of the increased balcony size. Early structural analysis identified that the originally proposed floor construction would not adequately accommodate the loads imposed by the enlarged balconies. The standard cast-in anchor arrangement could not safely transfer the required loads into the building structure.

Rather than allowing this issue to emerge during construction, Arc's engineering team proactively identified the problem during the design stage and collaborated with the wider project team to develop a solution. Following extensive review and consultation with structural engineers and anchor manufacturers, the floor construction was redesigned from a screed and precast slab arrangement to a 225mm reinforced cast-in-situ concrete slab capable of accommodating the upgraded anchor system.

This early intervention proved critical to the success of the project and established a robust design solution that was subsequently adopted across the duplex buildings in T3 and T4.

A further challenge involved maintaining the architectural vision for a sleek, lightweight balcony appearance despite the increased structural demands. Larger balcony projections naturally require larger structural members and support brackets. However, the client was keen to avoid a bulky visual appearance that would detract from the building façade.

Arc Engineering's design team carefully refined the structural arrangement to achieve both objectives. Enhanced cast-in anchors and increased steelwork were incorporated within a streamlined balcony profile, maintaining the clean architectural aesthetic while ensuring full structural compliance. The result was a balcony system that appeared elegant and lightweight despite carrying significantly greater loads than a conventional cantilevered balcony.

The project also demanded an exceptional level of façade coordination. Balcony support stubs had to penetrate varying façade build-ups including brick and rendered finishes. Even minor discrepancies in façade dimensions could result in clashes, excessive gaps or installation difficulties.

To overcome this challenge, Arc Engineering developed detailed interface drawings and coordinated extensively with the project design team to verify façade build-ups and finished dimensions. Installation tolerances were carefully engineered into the system, allowing the balconies to accommodate construction variances while maintaining a precise finished appearance.

One of the most visually distinctive elements of the project was the balustrade design. The architectural intent required a combination of vertical steel bar balustrades with glass windbreak panels positioned behind the railing system. This arrangement was unusual and required a completely bespoke solution.

The design team developed a modified balustrade system incorporating integrated support channels and enlarged top rails that allowed the glass panels to be seamlessly installed behind the vertical bars. This created the desired visual effect while maintaining compliance with structural and safety requirements. Additional loading generated by the glass panels was incorporated into the balcony structural calculations and anchor design.

The corner balconies on T5 introduced another layer of technical complexity. These balconies required non-standard cast-in anchor arrangements, creating conflicts where anchor zones overlapped within the concrete structure. Arc Engineering's engineers developed an innovative staggered anchor arrangement that eliminated clashes while maintaining structural integrity. This solution required multiple support stub configurations and meticulous coordination to ensure correct installation on site.

The project also featured integrated rainwater management within the balcony system. Powder-coated aluminium soffits were designed to collect and direct water into rainwater outlets connected back into the building drainage network. This required precise coordination of penetrations through balcony structures, decking and soffits while preserving both structural performance and visual quality.

Further challenges emerged during construction. Site installation experience identified opportunities to improve connection detailing between support stubs and balcony structures. Arc Engineering redesigned certain connection arrangements, relocating steel members to improve installation efficiency and accessibility. These improvements have since informed future balcony projects, demonstrating how continuous improvement and practical site experience contribute to innovation.

Operational excellence was central throughout the project. Every balcony was individually modelled, engineered and detailed. Comprehensive design calculations, fabrication drawings and installation layouts were produced to ensure accuracy from design through manufacture and installation. Offsite fabrication allowed strict quality control within Arc Engineering's workshop before components were delivered to site for installation.

The on-site installation required meticulous planning and coordination. Deep roof soffits and roof overhangs created extremely tight installation tolerances, making access for lifting operations particularly challenging. Arc Engineering overcame these constraints by sequencing the installation programme so that several balconies were installed before the roof was completed. Working within the confined site, the team employed a combination of a mobile crane and a 360° telehandler to safely manoeuvre and accurately position each offsite-manufactured balcony, demonstrating the operational excellence and adaptability required to deliver complex projects successfully.

The project required extensive collaboration between Arc Engineering, B&C Contractors, Evara, CCK Architects, Waterman Moylan Engineers, specialist structural engineers and cast-in anchor manufacturers. The successful delivery of such a technically demanding package was only possible through early engagement, open communication and a shared commitment to achieving the best outcome.

The completed balconies now provide residents with generous, attractive outdoor spaces while enhancing the architectural character of the development. The combination of structural ingenuity, aesthetic refinement and meticulous execution demonstrates Arc Engineering's ability to deliver complex architectural metalwork solutions at the highest level.

Arc Engineering Scope of Works:

59no. cantilevered balconies over 3 Blocks (of which 4no. were corner balconies)

Schock cast in anchors

HD Galvansied mild steel stubs

HD Galvanised Mild steel base

Aluminium Decking

Vertical Bar Balustrade with glass infill behind as wind break

Powdercoated aluminium soffit which collects water and diverts it to a RWO for connection back to downpipes

Here's what B&C Contractors said: "We engaged Arc Engineering to design and supply the balconies on our Cherrywood T5 project in November 2024. The site incorporated both block built duplexes and pre-cast concrete frame apartments.

From the outset and through the whole of the design process Arc were extremely knowledgeable and engaging. During design we came across some site specific details and challenges, all of which we were able to design our way around without effecting elevations or internal floor heights within the buildings.

When it came to construction stage Arc kept materials coming as per programme without delays, and on one or two occasions were able to accommodate us in areas were programme changed and we progressed ahead earlier then agreed.

The final product and the fitting stage was a seamless process with balconies arriving to site exactly when required and going straight into place, removing the risk of damage occurring while being stored on site. Overall through the whole site, what is a very complicated element of the build process went seamlessly and without delay."