EWI system for Rotherham Dorlonco renovations
4 04 2016
The Saint-Gobain Weber External Wall Insulation (EWI) system has been selected by Rotherham Metropolitan Borough Council (RMBC) for a property renovation project of 37 Dorlonco system-built homes in the Rawmarsh area of the town.
webertherm XM EWI with weberend RB Render Brick finish has been installed on these hard to treat properties providing greatly improved thermal performance while at the same time changing the streetscape for the benefit and wellbeing of the residents. A comfortable target U-value of 0.29W/m²K has been achieved from a pre-installation U-value of 1.05W/m²K. Four different colours have been used, some in combinations to match the duo-tone of the original facade, using Chestnut, Fallow, Umber and the new Georgian Red which have been selected from a palette of attractive colours. Additionally, a distressed finish has been achieved by artistic application of webersil P, a silicone enhanced masonry paint, to create an even more natural, aged brick effect which has been enthusiastically received.
The Dorlonco system was created by the Dorman Long Company and adopted by the Government when volume builds were urgently required in the aftermath of the First World War. They were considered to be the most successful of the post-WWI system-built house types in terms of both commercial viability and longevity of production. Originally created to house workers and their families, at the Company at Dormanstown, the first demonstration houses were built in 1919 and the system received enthusiastic support. The steel frame was designed to accept a number of different claddings, from conventional brickwork to render on a metal lath.
Like so many ‘temporary’ homes of that era, which are still standing, thermal efficiency must be improved and the webertherm EWI delivers this important upgrade. Rotherham Council awarded the main contract to Keepmoat who sub-contracted the EWI application to specialist applicator Hamilton First.
The webertherm XM EWI system specified for these homes uses 50mm phenolic insulation panels fixed to the external substrate which is covered and protected by the weberend RB Render Brick finish, a combination of two coloured mortars used together to create a superb brick-effect finish.
Once the insulation material has been fixed to the structure, an initial coat of weberend LAC render is applied over the insulation with a mesh-cloth reinforcement laid into it. A second pass of weberend LAC is then applied which is finished with a lightly comb-scratched surface to encourage the bond with the weberend RBB base coat which acts as the mortar line. This is applied at 7-8mm thick and ruled to achieve a flat, in-plane surface. When this has taken-up a 2-3mm coat of weberend RBF face coat is applied and the surface lightly textured with a soft bristle brush to create the brick face. When this coat has taken-up the brick pattern is marked carefully and cuts are made through the face coat render to expose the base coat to achieve an authentic, bonded brickwork appearance. The weberend RB system is a cost effective and attractive finish providing robust weather protection.
Adrian Morley, senior contracts manager for applicator Hamilton First is very positive about the quality of Weber products: “The material is great to work with and creates a good brick finish. The twin colourway was determined on a like-for-like basis with the original property. It was a pretty tough eight week program and winter is not the ideal climate for this work but we got the job done and everyone is pleased with the results.”
James Hamilton, of main contractor Keepmoat, is equally pleased with the project’s outcome: “Everyone at Rotherham is delighted with the visual results that retain the traditional community look and aesthetics; the residents are really happy with the much improved comfort provided by the insulation which has made their homes warmer and their bills lower. The quality of the Weber EWI system is first class and together with the skills and experience of our application contractor, we have achieved an excellent result on the Rawmarsh homes.”