The challenge was to create a new external insulation system incorporating next generation insulation materials, Vacuum Insulation Panels, to be used as the basis of a renovation solution for old, solid wall properties. The key aim was to reduce the thermal transmittance and provide an improved U-value without the need to install 150mm+ of insulation and thereby eradicating the inherent problems applying these thicknesses can create on existing structures.
The original solution was for the existing walls to be externally clad with 25mm thick Vacuum Insulation Panels topped with 40mm phenolic insulation. However this created the problem as to how the insulation system would be fixed to the structure, as if the panels were punctured in any way, their thermal performance would be dramatically reduced.
Wetherby designed a framework using 25mm phenolic battens that were mechanically fixed to the existing façade, to both hold the VIPs in place and to provide fixing points for the secondary layer of insulation. Nanopore Insulation Ltd produced factory pre-made panel sizes of 900mm and 500mm (VIPs cannot be cut on site) which were then placed between the battens. A secondary layer of Kingspan K5 40mm phenolic insulation was overlaid over the entire wall surface but mechanically fixed only through the battens. A Wetherby lightweight thin coat render system was then applied incorporating a fibreglass mesh and finished with a waterproof silicone texture render, giving a modern crisp external finish to the properties.
The combination of the two insulation types enabled the target U-valu of 0.15 W/m²K within only a 65mm depth which is impossible to achieve using existing insulation materials.