Cavity Wall (brick/block) is the predominant Build method for the UK housing industry with 70% of 27.4 million homes built with cavity walls.
The change to Part L1a in 2013 (which sets the guidelines for new residential house builds) brought a second compliance metric, Fabric Energy Efficiency Standard (FEES).
As a result of these requirements the fabric of the building needed to be more robust, with better insulation, reduced air leakage and improved thermal bridging.
The ultimate goal: the homeowner to switch the heating on less.
This ‘whole house’ approach meant maintaining a strong fabric performance to comply, without having to widen cavities and compromise plot efficiencies. This, in turn, would require more land to deliver the same number of homes.
Increasing wall cavity width would not only impact space required for each property. It would change the products required in the cavity construction: longer and stronger wall ties, thicker cavity closers and bigger door and window lintels.
The change in product combined with the extra land requirements would bring commercial challenges; it would either increase house prices or reduce house builder profit. Not a good choice either way.
Performance Vs Cost – the research
Research carried out across both Housebuilders and specifiers identified balancing cost and performance as a primary concern.
“Cost is assessed not between materials, but also on a whole-cavity or whole-site basis”
“The impact of increased cavity width requirements is identified as a key challenge which across the whole site can result in lost m² and impact on cost significantly”
Source: Celotex PIR Insulation Research 12th December 2014
To meet the industry needs in response to changing regulations, Celotex CF5000 was created; a unique product to solve a technical problem for housebuilders.
CF5000 is a high thermal performance full-fill solution for masonry cavity walls that helps to deliver a U-value within the wall of 0.18 W/m²K without the need to widen the cavity.
Comprising a rigid polyisocyanurate foam core adhesively bonded to aluminium foil facings on both sides, CF5000 is designed with the installer in mind. Easy to cut and available in 1200x450mm dimensions, it fits with standard cavity wall tie spacing to provide improved plot efficiencies on site.
Engineered board edges ship-lap to jigsaw together, effectively closing the gaps between the boards; this eliminates the passage of wind driven rain across the cavity (a requirement of Approved Document C).
Summary – The impact on the industry
As a company that leads the way in technological innovations, Celotex filled a huge gap in the market with the introduction of Celotex CF5000. Developed with a clear focus on maximising thermal efficiency with thinner solutions, the new and innovative CF5000 system gives architects, designers and specifiers the whole picture for full fill cavity wall applications.
Instead of choosing commercial value or performance, housebuilders using CF5000 can have both.