Innovative, high performance External Wall Insulation (EWI) by Saint-Gobain Weber has been specified for a proportion of homes in the extensive property upgrade programme being carried out by Stevenage Borough Council in Hertfordshire. Seventy six homes have benefitted from this improved thermal efficiency and aesthetics treatment in 2015 and a further 150 properties were included in the 2016 program.
The homes, constructed in the late 40s, early 50s, are a combination of traditional solid brick and Wimpey No Fines system build. The u-value achieved for the improved properties is an impressive 0.30 W/m²K, down from the original 1.98 W/m²K rating. The webertherm XM EWI system specified 90mm EPS insulation and high performance render to achieve this substantial improvement. Equally appealing for residents is the ‘new’ external visual results where four alternative render colours from the extensive palette of the weberplast TF acrylic based, pre-mixed decorative finishes have been applied. A new-for-this-project colour, Marshmallow, has been used alongside Antique Ivory, Winter White and Palest Pink.
Main contractor Wates Living Space, one of several contractors involved in this on-going renovation scheme, specified the Weber EWI system in order to meet the performance specification required by the Stevenage Borough Council property team who are familiar with the product’s qualities and attributes. Build-Therm Services, whose headquarters are in nearby St Albans, Hertfordshire, were responsible for the application.
Agron Sopjani, director of Build-Therm Services Limited responsible for the Stevenage program, acknowledges the value of the webertherm XM EWI system. “The application process is very straight-forward enabling our site teams to make good progress. Cutting the u-values down to these levels is impressive and the external finishes really lift the whole residential area. It’s clean and bright and together with the improved thermal performance it’s a real winner.”
The webertherm XM high performance external wall insulation and meshcloth reinforced polymer render system provides efficient thermal insulation for these refurbishments with the render coat and surface finish delivering water shedding capabilities to protect the building fabric. The 90mm of EPS insulation is mechanically fixed to the existing substrate surface and covered with a 6mm meshcloth reinforced coat of weberend LAC. This is a low density, polymer-modified cement-based mortar which is applied in two passes. weber PR310 primer is then applied prior to the application of the weberplast TF decorative finish.
“The External Wall Insulation installed in Stevenage has transformed our tenants’ homes by reducing heat loss, and making them easier to keep warm. Our tenants are very pleased with the results which should make considerable savings on their heating bills,” says Lydia Wisby, Stevenage Borough Council’s energy and sustainability co-ordinator.