When considering energy efficiency measures for your home in the UK, external wall insulation is a top contender, especially for houses without cavity walls that can easily be filled. Not only can it significantly reduce heating bills, but it also enhances the appearance and weatherproofing of a building. But what costs are involved, and what can you expect regarding savings and payback times? Here’s a detailed look at the costs of external wall insulation across different types of homes.

Detached Homes

• Size and Capacity: Typically around 147 sqm with four bedrooms.
• Cost: Insulation costs for detached homes can range between £15,000 to £20,000.
• Savings: Homeowners can save around £1,000 annually on heating bills.
• Payback Period: The investment can take around 20 years to pay back through savings in energy costs.

Semi-Detached Homes

• Size and Capacity: These are usually about 96 sqm with three bedrooms.
• Cost: For semi-detached houses, the insulation installation costs are between £8,000 and £10,000.
• Savings: Annually, you could look at savings of about £700.
• Payback Period: The payback period for this type of insulation is approximately 15 years.

Mid-Terraced Homes

• Size and Capacity: These homes range from 64 to 100 sqm and typically have two to three bedrooms.
• Cost: The cost to insulate mid-terraced houses usually falls between £6,000 and £8,000.
• Savings: Depending on the exact specifications and energy usage, savings can vary from £500 to £700 annually.
• Payback Period: You can expect the payback period to be 12 to 15 years.

Bungalows

• Size and Capacity: Generally, these are around 77 sqm with one to two bedrooms.
• Cost: Similar to mid-terraced homes, the insulation costs range from £6,000 to £8,000.
• Savings: Bungalows can also see an annual saving of about £700.
• Payback Period: The payback timeframe is comparable to that of mid-terraced homes, ranging from 12 to 15 years.

What materials can increase the costs?

The above pay scales are based on the average set of materials you may use. This includes EPS insulation boards and our most popular Silicone Render (EWI-075). However, there are several alternatives you can opt for throughout the process that will offer extra benefits but increase the external wall insulation cost.

Mineral wool

Mineral Wool is derived from natural rock or recycled slag from steel mills. It is melted down and spun into fine fibres that form the basis of the insulation material. This manufacturing process gives mineral wool a unique set of properties that are highly beneficial for insulation purposes. One of the standout features of Mineral Wool is its fire-resistant qualities. It is non-combustible and can withstand high temperatures, enhancing the safety of the building by providing a critical barrier against the spread of fire.

Mineral Wool is also an excellent sound absorber. It can provide a much-needed reduction in sound penetration for homes in noisy environments, such as those near busy roads or city centres, creating a quieter and more peaceful living environment. Unlike some insulation materials that can absorb water, Mineral Wool is hydrophobic—it repels water. This means it is less likely to become a breeding ground for mould and mildew, maintaining its insulative properties and indoor air quality over time.

Premium Bio Silicone Render and Nano Drex Silicone Render

We also manufacture topcoat materials that offer extra benefits. Both Premium Bio and Nano Drex Silicone Renders actively resist and break down signs of biological growth. This feature is particularly beneficial for homes located close to water, as humidity can cause the growth of contaminants. Salty air near the seaside is also harmful to most facades. However, EWI-076 and EWI-077 are specially formulated to resist the effects of salinity.