The Green Room: Episode 11 – External Wall Insulation (The Insulation Masterclass Series Pt 2)


The Green Room: What happens when you put two sustainability experts in a room and ask them all about external wall insulation? The second instalment of our Insulation Masterclass Series is all about those pesky solid walls and how to keep them warm. We talk every external wall insulation – how much it costs, how to do it, and whether it’s right for you.

What is external wall insulation?
If your house was built prior to the 1930s, the chances are that it will have solid walls – simply a solid layer of masonry bricks. Insulating your walls – regardless of whether they are cavity or solid (or even timber-framed) – is a great way to make your home more energy efficient. The insulation will minimise heat loss in the winter, saving you money on your heating bills. It will also stop your home getting too warm in the summer, helping to keep your home at a more comfortable temperature.

What are the advantages of external wall insulation?
– Compared to internal insulation, there is much less disruption to the household, as the work is carried out outside
– Renews your home’s external appearance and increases the lifetime of the brickwork
– Complements other refurbishment work
– An opportunity to fill cracks and holes in the brickwork, which will help reduce draughts(see Draught Proofing for more information)

What are the disadvantages of external wall insulation?
– More expensive than internal insulation
– Planning permission may be required
– Any work needs to comply with local building regulation
– May not solve all damp issues
– Work is not recommended if the building is not structurally sound

How much does external wall insulation cost?
The cost of solid wall insulation is roughly £100/m2, so it is not cheap. However, it can be really worthwhile in the long run. While government grants have now been wound down, there are occasionally local council grants available for eligible people, so it is worth checking. Also, some companies will offer finance.

Read more:
An Introduction to Solid Wall Insulation
What is External Wall Insulation Made From?
Are there any downsides to external wall insulation?
Is external wall insulation safe?
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