Marmox Thermoblock features in high profile Leicester Square retrofit

When complete the remodelled property overlooking one of the capital’s most famous public realms will offer 186,000 square feet of usable space over seven new floors of offices with retail units at street level.

There will also be accommodation on a newly created upper storey, behind what Make Architects describe as a fresh interpretation of the traditional mansard roof. Pivotal to this radical reconstruction has been the need to stabilise and strengthen the outer elevations which had been badly weakened by previous alterations over the past century. With a full facade retention structure in place and the basement area framed by a retaining wall, the project team’s solution involved raising an internal inner blockwork wall using aerated concrete. This is intended to improve the thermal performance of the exterior elevations as well as their regularity and soundness, while taking up the minimum interior space. As part of this, the project team elected to make use of the Marmox Thermoblocks as a means of minimising heat loss at the critical floor wall junction.

The 600mm long insulation units incorporate mini columns of high strength, low conductivity concrete to support the load of the wall above while the low lambda value insulation virtually eliminates the path for cold-bridging. The blocks are laid using normal bricklaying mortar with special Marmox Multibond sealant used to secure and seal the stepped joints, while an integral layer of mesh on the upper and lower surfaces offers a good mortar bond for blocklaying to continue in the conventional manner.

In total over 1000 Thermoblocks were supplied by the Islington branch of Travis Perkins, helping to create a continuous horizontal thermal break beneath the new wall rising from the basement of 48 Leicester Square, ensuring it will meet the current building regulations and that the structure will endure for many decades to come.