The Housing Association brought in main contractor Walter Carefoot & Sons to upgrade the block of flats with improvements to the wall insulation, the windows and the roof. Subcontractor, Castle Contractors, took on the task of upgrading the flat roof, bringing the insulation up to part L standards and giving the refurbished roof a lifespan of at least 25 years.
Castle Contractors laid 90mm Kempertherm F insulation board from Kemper System directly onto the existing prepared 20-year-old three-layer bituminous felt roof, using the existing felt as the vapour control layer. Kempertherm F has a tongue and groove interlocking edge that reduces cold bridging and allows for a neater finish over uneven existing surfaces. The insulation board was then coated with Kemper System’s ‘D’ primer before installing a durable, waterproof roof surface using Kemper System’s Kemperol V210 cold liquid-applied system. The Kemperol V210 liquid resin was applied to the roof and the system’s non-woven fleece was then laid into it, with a 50mm overlap at the joins to ensure a fully watertight finish. As the fleece was laid, more resin was then applied saturating the fleece and completing the installation in a single process. The system was then cured to form a seamless, fully reinforced waterproof membrane that bonds directly to the substrate and cannot delaminate, protecting the building and the new insulation.
The flats now have a U-value of 0.18 W/m2K, bringing them up to Part L standard.
“Clitheroe’s elevated position makes it a pretty chilly place to live in the winter and the roof here was visibly tired and in need of an upgrade,” said Mark Atherton from Castle Contractors. “The Kemper System solution will ensure that the flats are warmer, more energy efficient and reliably watertight, whatever the weather and the project proves that older buildings can successfully meet modern building regulations.”