External Wall Insulation (EWI) by Saint-Gobain Weber has been specified for the thermal and aesthetic upgrade of Weir properties owned by East Ayrshire District Council. The Weber.therm XM EWI system is being applied in a two-phase programme of over 350 homes, a mix of tenancy and owner occupancy. Phase one is now complete and phase two, some 248 properties, is underway.
The Weir properties being upgraded are post-World War II timber construction and are poorly insulated and expensive to heat. East Ayrshire District Council’s project has been led by senior architect Ernie Tew, who not only managed the technical elements of the scheme but also produced and managed the financial grant submission. “We wanted a cost-effective solution for externally refurbishing these houses that would enable the upgrade to be carried out without having to temporarily relocate our residents. The system had to create a watertight and thermally efficient building envelope, reduce CO2 emissions, cut fuel consumption and change the external appearance of the properties,” said Mr Tew.
Saint-Gobain Weber calculated a greatly improved target U-value of 0.29 W/m²K from a pre-application value of 2.1 W/m²K. Each property requires 84m² of Weber.therm XM , which features expanded polystyrene (EPS) insulation that is mechanically fixed to the timber structure. The main insulation thickness is 90mm with 110mm being applied to level some facades and 70mm EPS being used in the gable ends to achieve a level consistency.
The render process requires two passes of Weber.rend LAC cementitious render over an embedded fibreglass reinforcement meshcloth to give a robust render coat. The second coat is Weber.rend PTC, a polymer-modified, cement-based mortar which acts as the dry dash colour-base and adhesive on which the selected aggregate blends are carried. The dry-dash stones are then applied to give the very best weather and impact protection to this multi-layered process.
Structural repair and construction company Skyform Specialist Contracts, Glasgow, a Weber recommended EWI installer, was appointed by the Council to carry out the application work. Skyform’s project manager, Gary Meredith, commented: “Bringing the wall surfaces up to the same level with the insulation not only makes it easier to apply the render coats but makes a substantial improvement in the appearance of the properties. The Weber.therm XM system is straightforward and reliable and we look forward to making continued progress with this project.”