The advantages offered by full fill insulation over part fill in masonry cavity walls have been brought into focus by Knauf Insulation. One of their key findings being that the installed cost of DriTherm glass mineral wool cavity slabs show almost a 50 per cent saving over part fill rigid foam boards.
Costings were calculated using the SPONS Architects and Builders Price Book 2008 and are based on the requirements for a typical semi-detached house with a target U-value of 0.29 W/m2K. The material and labour costs for installing 1000m2 of 100mm thick DriTherm Cavity Slabs was costed at just £365.60 on the basis of an 80m2 area. This represents almost half the cost of achieving the same level of thermal performance compared to using part fill rigid foam boards.
But the installed cost is far from being the only benefit, it’s also easier to achieve more reliable thermal performance than the alternative part fill rigid foam board solution. The flexibility of DriTherm Cavity Slabs in being able to follow wall contours results in far fewer airspaces on the warm side of the insulation than would be experienced when installing rigid foam boards. With DriTherm, the slabs also knit together at joints preventing heat loss through the gaps commonly associated with rigid foam boards.
DriTherm is now manufactured using patented ECOSE® Technology which has recently been introduced across the entire Knauf Insulation glass mineral wool product range. Mineral wool with patented ECOSE® Technology provides sustainability benefits never achieved before with any type of insulation. The process reduces the embodied energy whilst providing superior environmental performance. The new mineral wool products get their brown colour from a formaldehyde-free binder derived from bio-based materials instead of petroleum-based chemicals. The process has been developed to enhance the product’s sustainability without compromising the already excellent thermal, acoustic and fire performance characteristics.
DriTherm offers moisture resistance you can count on with a formal 50 year guarantee to prevent the transmission of liquid water from the outer masonry leaf to the inner masonry leaf. The entire DriTherm Cavity Slab range is BBA certified for all exposure zones and boasts a 35 year successful performance heritage with millions of cavities already insulated.
On top of all these benefits, full fill DriTherm requires less installation time than rigid foam boards meaning greater productivity for installers. Whereas rigid foam boards are more difficult to cut and require a greater degree of care and time to install correctly, DriTherm Cavity Slabs are quick to install and avoid the problems associated with part fill cavities. There is also no requirement for special retaining discs or cavity barriers with full fill DriTherm.
“With housebuilders having to work towards Zero Carbon homes by 2016 and in the light of the current economic downturn, the ability to recognise and inform them of the numerous advantages of full fill cavity wall insulation is extremely important”, remarks Alex Cairns, market manager for residential new build at Knauf Insulation. “The superiority of DriTherm Cavity Slabs is clearly demonstrated through its wide range of benefits, and with ECOSE® Technology, our glass mineral wool is now even more sustainable, providing the installer with an environmentally friendly and high performance solution, whatever the project.”