Housing Specification Blog

EWI – an effective tea cosy for ageing housing stock

October 25, 2012 Alexandra Blakeman Housing Issues

If we’re to believe the forecasts, we’re in for some much colder weather tomorrow and the week ahead. Winter has officially arrived. With rising heating bills and energy costs, I bet, that despite the foretold plummeting temperatures, you’ll be reluctant to crank up your heating system.

Around a third of a house’s heat is lost through its walls. Adequate insulation is vital for retaining internal heat and reducing costly energy bills. In the next issue of Housing Specification, we’ll be looking at refurbishment, external walls and insulation. As a little precursor, I’m going to investigate the pros and cons of external wall insulation (EWI).

External wall insulation being applied to a solid wall. Click on image for original source.

Houses have two different types of walls; solid and cavity walls. If your property was built after the 1920s, it’s likely that you’ll have the latter – where two walls are separated by a small gap (a cavity) which acts as a heat barrier. Solid walls are less efficient at retaining heat, often allowing around twice as much heat to pass through them.

Installation of EWI can be pricey, so it’s advisable to combine the work with other home improvement projects. Unlike Internal wall insulation, EWI can be installed without disrupting or impinging on valuable living space.

If you’re constantly battling with damp, EWI can reduce condensation on internal walls as the new cladding protects the wall from further wetting.  Severe damp problems would have to be addressed before application. Likewise, if walls are structurally unsound or irreparable, EWI can’t be applied.

Ageing properties probably have the most to gain from EWI installation. Not only does it improve the appearance of exterior walls, it also guarantees a uniform thermal performance without any cold bridging. The result? A cosy, draught free house with reduced heating costs.

Adequate access to external walls is vital for the application of EWI. Sounds simple, but without the necessary space, installers won’t be able to carry out the work.

For more information and advice on EWI costings, The Energy Saving Trust website is a useful resource.

Since you’ve got us talking about EWI…

Why wait when you can have weber.therm XP?

Saint-Gobain Weber, the UK formulator and manufacturer of innovative materials in the façades, exterior wall insulation, concrete repair, tile fixing and floor sectors, has improved the seasonal application characteristics of weber.therm M1 render used in their market leading weber.therm XP External Wall Insulation (EWI) system.

In the construction industry, time is money so why wait unnecessarily on site when the improved weber.therm XP, with innovative technology that allows the product to work in harmony with seasonal conditions, can save valuable time by minimising the installation schedule. This development allows contractors to scrape the render to a same day finish in the summer and achieve a next day finish in the winter, resulting in shorter programme periods, fewer on-site hours and allowing faster access to other trades.


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