Why Solid Walls Are a Problem
If your home was built before the 1930s, there's a good chance it has solid walls rather than cavity walls. Solid walls lose heat at roughly twice the rate of unfilled cavity walls, and they can't be treated with standard cavity wall insulation.
That's where external wall insulation (EWI) comes in. It wraps your home in a layer of insulation fixed to the outside, finished with a protective render. The result is a warmer home, lower bills, and often a refreshed exterior appearance.
How Much Could You Save?
The Energy Saving Trust estimates that external wall insulation on a typical semi-detached home saves around £400 per year on heating bills. For a detached house, savings can reach £500 or more.
Here's a comparison:
- Semi-detached (3 bed): Save approximately £400 per year
- Detached (4 bed): Save approximately £500 per year
- End-terrace: Save approximately £310 per year
These are significant savings, and they add up quickly over the 30+ year lifespan of the insulation.
What Does the Process Involve?
EWI installation is a bigger job than loft or cavity wall insulation, but the results are transformative. Here's what to expect:
- Preparation: Scaffolding is erected and external fittings (downpipes, meters) are temporarily moved
- Insulation boards: Rigid insulation panels are mechanically fixed to the external walls
- Mesh layer: A reinforcing mesh is embedded in adhesive over the boards
- Render finish: A weather-resistant render is applied in your choice of colour and texture
- Reinstatement: External fittings are refitted and scaffolding removed
The whole process typically takes 2-3 weeks for a semi-detached home, depending on the property size and any complications.
Will It Change How My Home Looks?
Yes - and usually for the better. The rendered finish gives older properties a clean, modern appearance. You can choose from a range of colours and textures, and many homeowners tell us their home looks significantly better afterwards.
If you live in a conservation area or a listed building, there may be planning restrictions. We'll check this for you before any work begins.
Grant Funding for External Wall Insulation
EWI is one of the most expensive energy efficiency measures to install privately, with costs ranging from £8,000 to £15,000 depending on the property. However, it's also one of the measures most commonly funded through government grants.
Under the ECO4 scheme, eligible homeowners can receive fully funded external wall insulation. Eligibility is usually based on:
- Receiving qualifying benefits (Universal Credit, Pension Credit, etc.)
- Living in a property with an EPC rating of D or below
- Having solid walls or hard-to-treat cavities
Check your eligibility now - you could save thousands on installation costs.
Is EWI Right for You?
External wall insulation works best for:
- Pre-1930s solid-walled homes
- Properties with hard-to-treat narrow cavities
- Homes where internal wall insulation would reduce room sizes unacceptably
- Properties that would benefit from an exterior refresh
If you're unsure whether your walls are solid or cavity, we can tell you during a free survey. Get in touch and we'll assess your property and explain your options.