floors & floor coverings 55
Flooring is the foundation
Adrian Crow of Insulslab explains the theory behind delivering a foundation up to finished floor level – and how this can pay dividends from both a commercial and performance perspective.
foundation construction, housebuilders are increasingly recognising the benefit of adopting a simplified approach that combines the two. Foundation methods typically fall outside of
W
the Part L compliance remit. This is because traditional systems – such as suspended slabs, beam and block floors or raft foundations – are classified in groundworks packages and do not form part of the exterior envelope. By contrast, fully integrated foundation systems can deliver the foundation up to ground floor level, which as part of the envelope contributes to building performance against Part L requirements and SAP calculations.
Going to ground
When seeking to improve the overall thermal performance of a building through the use of a fully integrated foundation system, the highest U-values are achieved by using products that incorporate insulation within their design. For example, some systems are constructed using expanded polystyrene (EPS) pods. These light- weight pods are simply laid in place in a prepared formation and then steel fibre reinforced concrete (SFRC) is poured over them to deliver the foundation and slab up to finished ground floor level. This type of build-up can typically achieve U-values as low as 0.10-0.13W/m2
K
(depending on P/A ratio). In contrast, for traditional floor build-ups to
achieve the same level of thermal performance, the insulation layer with a lambda value of 0.022 W/mK on top or below of the foundation would need to be approximately 160 mm to 180 mm thick. As well as representing a significant increase in insulation material cost, such a thickness of floor depth will negatively impact on the foundation depth.
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hile the flooring package is traditionally treated as a separate concern to the groundworks and
The key to the performance of super-insulated
foundation systems is that insulation is inherent in the design. As well as providing high levels of thermal insulation, the pods form part of the foundation structure, which ultimately helps reduce the foundation weight and utilises the established waffle slab construction technique.
Driving efficiencies and performance
Beyond the proven thermal insulation benefits of such highly insulated and integrated foundation systems, housebuilders are increasingly adopting this modern method of construction thanks to its speed of installation and the cost savings that can be achieved. For example, compared with traditional build
methods, the nature of an integrated foundation system means a simplified installation process and ultimately helps makes site programmes more efficient. Less time is needed to prepare the ground for construction, as no trenches are
required, and the system itself is quick and easy to install. These factors can culminate in a cost reduction, both on materials and labour. In addition, the minimal excavation translates
into reduced spoil to cart away, as well as less site traffic. Finally, the lightweight pods and use of SFRC, which eliminates the requirement for steel reinforcement, minimise manual handling on-site and contribute to a positive health and safety environment.
At a glance
Given the superior thermal performance of inte- grated systems that incorporate EPS pods within their design, developers often favour this build type when higher levels of insulation are required. How- ever, cost and time savings are increasingly prevailing factors during the specification and pro- curement processes. The table on the following page provides a quick comparison of the relative benefits of fully integrated foundation systems with traditional techniques.
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