Minimising linear thermal bridges at the wall connection to the floor, or floor slab, has been a perennial problem with reinforced concrete construction. However, a dedicated new solution – the Sconnex type W – has now been introduced by Schöck.
A high-profile project involving the new Schöck thermally insulating wall connection is Haberdashers’ Aske’s Boys’ School, at Elstree in Hertfordshire. Recognised as being one of the leading independent boys’ schools in the country, it sets exemplary standards, not just in educational terms, but in its facilities as well. As demonstrated by the new extension to the Preparatory School.
A two-storey contemporary extension
This is a standalone building within the campus and Hampshire based cube_design architects were commissioned to produce a concept design for three additional classrooms, along with the relocation of changing facilities. Jane Lock-Smith, the founder of cube_design and RIBA Client Design Advisor within the BSF programme, takes up the story:
“The design is respectful to the style of the existing building, but offers a contemporary twist through the use of full height glazing and charred timber cladding. The use of a colonnade minimises the buildings footprint.   In our detailing we took into account that around 40% of all thermal bridges in a building are caused by walls and supports.  The Schöck solution offers an application-friendly, high-quality solution that contributes to a permanently sustainable building concept”.
A serious source of linear thermal bridges
The construction of the Preparatory School extension is of reinforced concrete; and traditionally wall connections to the floor, or floor slab, have been a major source of linear thermal bridges.
The result being not just serious energy loss, but also the high risk of condensation. This can easily lead to mould growth, resulting in possible structural damage and worse, posing a health risk to the occupants. As the market leaders in the development of Isokorb structural thermal breaks for balconies and other cantilever constructions, Schöck has now used this expertise to produce a thermally insulating wall connection that combines outstanding insulation performance with dependable load-bearing capacity.
Sconnex is a unique solution
This new thermally insulating connection for reinforced concrete walls is unique in a number of ways. It minimises the thermal bridge between the exterior wall insulation and the insulation above the floor slab, increasing the energy efficiency of the entire building. Thermal losses are greatly reduced and the surface temperature in the room increases to considerably more than the critical dew point temperature. Heating costs are lower and the PSI of the connected reinforced concrete wall is reduced by up to 90 percent. The outstanding insulation performance is combined with an excellent load bearing capacity, which transmits very high pressure, tensile and shear forces, both in the  longitudinal and transverse direction. Made possible by the use of a pressure buffer consisting of ultra-high performance fibre reinforced concrete which achieves compressive strength levels in excess of 175 N/mm2. A further important benefit is the significant cost reduction achieved when compared to installing insulation beneath the floor slab.
For further information on the new Sconnex type W product; contact Schöck on 01865 290 890; or download the brochure at www.schoeck.com