Solid wall insulation – Greengauge advises

A significant proportion of the houses in the UK were constructed before 1920. If this applies to your house, it’s likely that it’s of a solid wall construction.

Many people are interested in adding insulation to their homes to reduce energy bills and environmental impact, and increase comfort and health – although when done properly these objectives can be effectively and safely achieved, there are many issues to consider and problems to avoid:

External wall insulation (EWI) avoids the loss of floor space and disruption within the home, but alters the external appearance, whilst internal wall insulation (IWI) preserves the appearance from the street, but causes some internal disruption and takes up some floor area.

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If opting for IWI, care should be taken when designing and specifying the insulation to avoid building up moisture to dangerous levels anywhere in the construction. To get a more accurate assessment, ask for analysis according to BS EN 15026, completed by a competent person using “Wufi” or a similar software tool.

EWI is generally safer – but there are plenty of examples of failure too. The main two causes are gaps in the insulation leaving cold spots (e.g. around utility meter boxes), and poorly designed or executed details that don’t prevent rain getting behind the insulation.


Greengauge offer comprehensive advice on Deep Energy Retrofits, including building energy modelling (how much insulation should I have and where?), Wufi Analysis (how much insulation is safe?) and Services Design (including heating, ventilation).

For more information visit or get in touch This email address is being protected from spambots. You need JavaScript enabled to view it.


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