Halfen thermal breaks used to bring striking 17-storey precast concrete exoskeleton to life

Set around a central public square with outdoor market, cafés, shops and leisure facilities, Coronation Square is a contemporary mega-development breathing new life into Leyton, in the heart of East London.

Providing a total of 750 modern 1, 2 and 3-bedroom apartments thoughtfully designed for professionals, families and first-time buyers, the development includes a purpose-built nursery, NHS health hub and extensive leisure facilities, as well as individual balcony areas where residents can look out over landscaped courtyards and gardens.

Spearheading the regeneration of this area of East London, the development is laid out over a number of blocks of differing design and height, typically featuring contemporary red London Brick façades to complement the area’s historic architecture, anchored by a stunning 17-storey white concrete tower with visually impactful structural grid façade, created using an unusual precast concrete exoskeleton.

The Challenge 

Precast concrete cantilever balconies have been used extensively throughout the development to create a distinctive architectural feature, optimising living space and helping to create a more sustainable, light and airy, internal environment for residents.

This created a particular challenge in the 17-storey tower, where the design of the precast concrete exoskeleton created complex and heavy loadings on the balconies, and therefore on the thermal break connectors supporting the precast cantilever slab and precast frame structure at roof level.

High capacity thermal break connectors were therefore essential to prevent noise transfer into the main structure and provide a high level of insulation to prevent thermal bridging across the slab.

The Solution

Technical specialists from Leviat were approached by Developer, Taylor Wimpey, and Structural Engineer, Manhire, to provide a support and thermal break solution for the complex construction, ensuring that each level of the precast exoskeleton would also remain structurally independent. 

After calculating the deflections at each floor level, the decision was taken to use Leviat’s high capacity Halfen HIT-SP MVXL thermal breaks, the most thermally efficient balcony connector in the Halfen range, specifically designed to transfer bending moments and high positive and negative shear forces in heavy and complex balcony structures.

The connector would not only limit slab deflection to maintain structural independence, but included a special cassette section containing 120mm of non-combustible mineral wool, preventing thermal bridging across the joint and providing a 2-hour REI 120 fire rating for optimum fire safety.

Concrete frame specialists, O’Halloran & O’Brien, installed a total of 1,400m of the Halfen HIT-SP MVXL thermal breaks throughout the project to support the concrete cantilever balconies.

Leviat’s new high capacity Halfen HIT-HP DDL units, 350mm high, were also installed at roof level to support and thermally break the architectural precast roof structure, and a precast horizontal feature band, thermally broken by Halfen HIT-HP units, was innovatively used to support the masonry façade on some elevations.