Thermoblock premieres in Leicester Square project

The refurbishment of a landmark listed property on London’s Leicester Square has seen Marmox Thermoblocks specified in very large quantities for an unusual application. Number 48 Leicester Square is being completely redeveloped behind the retained 1920s stone façade, with Make Architects leading the design team on behalf of client, Linseed Assets, while Pacific Construction is the main contractor.

When complete the remodeled 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 stabilize 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 minimizing heat loss at the critical floor wall junction.

The 600 mm 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.  They 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 block-laying to continue in the conventional manner.

In total over 1000 of the 640X140X65 mm Thermoblocks were supplied by the Islington branch of Travis Perkins, helping 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.