The Landmark project at 22 Marsh Wall, close to London’s Canary Wharf, is one of the tallest mixed use developments in the City, with a 31-storey West Tower and an imperious 45-storey East Tower. The exteriors of the towers are façades set behind a continuous skin of glazing, which gives the structure a lightweight reflective surface that allows the building to change in appearance depending on the quality of natural light. Internally the various sized apartments are finished to an exceptionally high standard and the attention to detail is obvious about everything to do with the Landmark. This extends to the connectivity involving the cantilever and inset balconies designed into the scheme. As elements which project through the building envelope, breaking the insulation layer in the process, balconies and other cantilever connections are notorious for creating thermal bridges.

One of the consequences of this, particularly on such exposed structures, is local heat loss, resulting in more energy being required to maintain the internal temperature of the building; While this is a very important aspect of thermal bridging, low internal surface temperatures in the area of the thermal bridge can also cause serious condensation, if they are below the dew point of the air. This in turn can lead not only to structural integrity problems with absorbent materials such as insulation products or plasterboard, but the occurrence of mould growth too, which can have serious implications for the occupants in the form of respiratory problems.

There are very few really effective solutions to combating the various negative aspects of thermal bridges, but one proven answer is the Schöck Isokorb thermal break, a range of products that allow connections to be made between concrete-to-concrete, concrete-to-steel and steel-to-steel. It is the Isokorb type K, specifically for concrete-to–concrete connectivity, that has been incorporated into the Landmark development. It has outstanding thermal insulation properties and dramatically reduces thermal energy loss in connective areas by guaranteeing the homogeneity of the thermal envelope between cantilever structures and the internal floor. It also transfers load and maintains full structural integrity, while at the same time enabling inner surface area temperatures to remain well in excess of those likely to cause mould formation and condensation – both of which are completely eliminated in room areas adjacent to the balconies.

The project was undertaken on a design and construct basis, with the core constructed using the “jump-form” technique ahead of the concrete floors, which enabled the frame and groundworks contractor, to complete a superstructure floor every week.

The Isokorb range provides BBA Certification and LABC Registration and meets full compliance with the relevant UK building regulations. In addition, there is also compliance with the Government Standard Assessment Procedure, SAP 2009, concerning CO2 emissions from buildings and respectively heat losses through non-repeating thermal bridges.