We have seen a steady rise in the adoption of super insulated foundation systems over the past few years. While this was initially driven by the time and cost savings that these solutions can facilitate, in more recent times the need to achieve superior levels of thermal performance has been a more prominent specification factor. Forming part of the exterior envelope, super insulated foundation systems support the Fabric First approach to building design. In doing so, they enable superior thermal performance to be achieved in the floor build-up, which ultimately allows greater flexibility in the wall and roof constructions.
As compared with traditional foundation techniques, super insulated foundation systems can be designed to significantly improve thermal performance and increase speed of installation at the same time. In some cases these benefits are achieved by using special products to build up the foundation structure, including the thermal insulation. Steel fibre reinforced concrete (SFRC) is also an option being used increasingly to replace traditional steel reinforcement.
In spite of the contribution that foundations can potentially make to the overall thermal performance of the building fabric, they are often overlooked in this regard. This is because historically the thermal performance of this elevation has generally been achieved through the floor build-up and not integrated as part of the foundation design.
Super insulated foundation systems vary greatly to traditional methods, because from a Fabric First perspective, they negate the need for an additional screed layer which means the foundation system forms part of the building envelope. As super insulated foundations can achieve U-values as low as 0.12w/m2K without increasing floor depth, these systems ultimately improve the overall performance of the building fabric. In doing so, they provide an immediate uplift in SAP ratings, removing the need to wholesale redesign the building envelope when needing to achieve improved thermal performance with an existing building design.