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Weber Saint-Gobain - Official website of the company

Transform homes with webertherm External Wall Insulation (EWI) systems

22 07 2010

Innovative external wall insulation (EWI) systems are making a real difference to the thermal improvement and external redecoration of solid wall and non-traditional buildings. Weber, the specialist manufacturer of industrial mortar products, its core product range consisting of external renders which include A+ Green Guide Rating monocouche renders – weberpral M and weberpral D - is leading the way in EWI systems that are transforming ‘hard to heat’ homes.

In the modernisation of Peterborough’s 1950’s homes, originally constructed to house evacuated Londoner’s which were, at that time, labelled ‘temporary’, are now receiving a total facelift.  Some 60 years later, a major refurbishment project is underway to bring these Cross Keys Homes closer to today’s standard of thermal performance.  A key factor in this plan is the use of the webertherm External Wall Insulation (EWI) system.  

Nearly 600 homes are undergoing improvements by housing association Cross Keys Homes in a multi-million pound project that has benefited from £1m of support secured by Weber from the CERT funding initiative.  Main contractor Mears has renewed roofs, fascias and soffits with specialist applicators, Retrofit Limited and Lawtec Limited, handling the £3.73 million webertherm External Wall Insulation (EWI) system installation.  

Here a variety of different finishes are being used with the versatile webertherm EWI system to allow properties to keep their original character while achieving visual variety.  To date, and over several phases, this has included webertherm XM which uses through coloured, decorative and weather resistant render to the insulation system while other properties have been finished with a real brick appearance in webertherm RB.  

Striking results have been achieved using weberend RB which produces a superb brick look-alike finish in just a fraction of the time and at a fraction of the cost of full brickwork cladding. weberend RB is the combination of two polymer modified mortars used in conjunction to create the brick work pattern.  Alternatively, a real brick finish is available from Weber and can be achieved using webertherm XB.  

Insulation is fixed to the original substrate of the building followed by a basecoat render with meshcloth reinforcement. Once set, the surface is lightly comb scratched prior to the application of the weberend RBB render coat which acts as the “mortar” joint and is available in eight different colours.

When the RBB coat has “taken-up” and is firm enough to allow application of the face coat, 2–3mm of weberend RBF is applied and stippled with a soft bristle brush to give the “brick” effect finish. Eight different colours of face render are available, allowing the client to replicate almost any brick and mortar combination which is particularly important when matching in with existing properties.  

The brick pattern is achieved by cutting through the weberend RBF face coat to expose the contrasting RBB render thus creating the attractive brick pattern finish. What’s neat about the system is that any brick pattern can be achieved including conventional ‘cavity’ layout as well as ‘header and stretcher’ bonding of traditional solid walls. Correctly applied this system is often mistaken for high quality bricklaying - even by experienced tradesmen!  

The weberend RB brick effect render system, used as part of the webertherm XM EWI system, is transforming both the aesthetics and thermal efficiency of non-traditional and solid wall homes in Peterborough.  

The dramatic changes to the aesthetics of these Peterborough homes are matched by the changes in performance.  Householders report new levels of warmth and comfort.  The original prefabricated steel shell bungalows on Welland Close for example had no insulation at all other than the plaster board lining for the room interiors.  In winter the steel is ice cold and in summer heat radiates off the metal internally making this one of the most uncomfortable construction methods ever.  Residents are now reporting that not only are their homes much quieter inside but the properties are far warmer, contributing dramatically to reduced heating costs in winter, while aesthetically they have changed beyond compare.