External Wall Insulation Costs, Quotes & Savings 2021

External wall insulation wraps the outside of your home block thermal leaks and leaving you and your family warmer.

Solid walls don’t trap heat efficiently and twice as much heat can escape through them as through cavity walls. Upgrading them with external wall insulation is a great idea, as not only will you save on your energy bills, but you’ll also protect your home by preventing damp and give the exterior a makeover.

Whilst insulating cavity walls is a quick and relatively cheap process, the insulation of solid walls can prove to be quite a bit more expensive. For a free quote, complete the form above.

What’s In This Guide?

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What Is External Wall Insulation & Is My House Suitable?

Most British homes built before 1930, were built with solid walls, leaving no cavity that can be filled with insulation. These houses can still be brought up to modern standards by insulating the external walls and improving the building seal. This method of home insulation reduces heat loss and, depending on the finish used, protects against the elements.

We wrote extensively on how to test if your home has solid walls or cavity walls here.


The Insulation Process

  1. Adhesive mortar is used to fix the prefabricated insulation panels to the outside wall.
  2. Special fixings are used to secure the panels to the wall.
  3. The insulating panels and fixings are then covered in mortar.
  4. An insulating mesh is then fixed to the mortar to hold everything in place safely.
  5. Once the mortar sets, it’s sanded and painted in primer to prepare for the final stage.
  6. A render and colour is applied as per the clients choice.

The first step is to check if your home has an existing external surface or render. If this surface is able to support the external insulation it can be applied directly and reduce the cost of the process. Should your existing external wall surface be unable to support the new layer, it must be removed down to the brickwork.

All external pipework, satellite dishes and obstacles must be removed prior to installing external wall insulation. This can be time consuming and is one of the reasons this process of home insulation is more expensive.


External Home Insulation: The Savings

These figures are estimates based on averages. The savings you will see will depend the existing level of insulation in your home and home heating system.

How Much Does External Wall Insulation Cost?

The cost of external insulation of solid walls is about £120 per square metre. So, insulation of small apartments will cost in the region of £9,500, while insulating a large detached house can come to around £25,000. The investment will repay you over time but the not for several years. The price of external insulation can range significantly depending on various factors. For example, the scope of work, the accessibility of walls, etc.

Internal insulation costs are generally lower and ranges between £4,500 and £18,000. However, the payback period is still quite long.

Property Type
Detached£15,000 – £20,000
Semi Detached£8,500 –£10,000
Terrace£6,000 – £8,000
Prices are estimates

Adding up the wall space that needs to be insulated is a little more accurate technique to figure out the cost of the work. The typical cost of a job is around £100 per square meter. That means the cost of a 60 square meter work will be £6,000.

Customers frequently ignore windows and doors from this category, which leads to an overestimate of cost. Unfortunately, it is much easier to insulate a wall without windows since adding the detailing around the windows and achieving a great clean finish around the reveals takes a lot more time. As a result, we recommend calculating your square meterage by measuring the entire wall from ground to gutter and end to end.

In most cases, the price listed below will encompass pipe extension work as well as the standard wall fixings. If you have a lot of intricate repairs to make, or if you need a gas appliance flue expanded, you should expect an extra several hundred pounds to finish the job.

Materials are usually inexpensive when compared to the cost of labor, thus they don’t really add much to the final cost of the project. There are some instances where the cost of materials has an impact on the price:

Rockwool is a popular type of insulating material that architects and builders opted for recently. It is more permeable and less messy to deal with than other options. But the flip side of the coin is that it will add 20-30% to the cost of a normal work.

Double or Panzer Mesh uses two layers of mesh or an extra-strong ‘Panzer Mesh’ that adds roughly 20% to the cost of the job. This is only used in situations where the external wall must be protected from knocks or tears, such as a wall adjacent to a public sidewalk.

Scaffold can be highly expensive, and the cost will vary depending on the work. If the job is reasonably simple, a scaffold contractor might charge £1,500 on a typical semi-detached dwelling. The cost will rise if there are more than two levels or if there are tricky spots with restricted access or obstructions in the way, such as a conservatory.

If you want a really dark color, or if you want to include detailing or other elements in multiple colors, the price will rise proportionately. This should be in the hundreds of pounds rather than thousands of pounds, so it shouldn’t be a significant cost impact.

External Wall Home Insulation Grants

The Energy Company Obligations Scheme provides government grants (ECO)

Grants are divided into three categories:

  • If you get certain benefits, you may be eligible for HHRCO.
  • Flexible Eligibility (HHRCO Flex) Is available if you live in energy-inefficient social housing or meet certain criteria established by your local council.
  • Contact a PAS2030 accredited EWI installer with an ECO financing contract to apply for a grant. They’ll come to your house, examine it, and tell you how much money you might be eligible for.

There is no set funding amount; instead, it is calculated using a unique formula based on the sort of property you own.

Is there any financial assistance for external wall insulation?

External wall insulation (EWI) grants are available, although they are unlikely to cover the entire cost of the installation.

In some cases, EWI scholarships are supplemented with additional sources of support. Some local governments, for example, run EWI programs that combine various financing sources. Visit your local authority’s website or contact them directly to see whether they are conducting a scheme.

In most circumstances, the homeowner will need to supplement the grant with their own funds or a loan to make up the difference.

If you receive certain state benefits, you may be eligible for a greater grant to cover a larger portion of the cost.

External Wall Insulation: Considerations

To install the external insulation a layer of insulating material will have to be fixed to the wall with the help of mechanical fixings and covered with shielding layers of plaster covering or cladding. Usually, plaster covering is cheaper than the cladding.

External wall installation can be done quickly if the outside of your house is suitable and depending on the design.

However, if the existing coating of your building can’t support the insulating layers or is cracked, it will have to be removed or fixed which can increase the cost of the project.

If your building is a period property and you want to improve its appearance whilst increasing the heating efficiency, you may be advised to use custom insulation solutions. For this type of insulation, various materials can be used. They include stone, glass, terracotta tiles or oak weatherboarding.

It is vital to ensure that there’s no penetrating damp inside the walls before installing the external insulation. Even though the damp can be temporarily covered with the wall insulation, the problem will keep growing.

External insulation will be most beneficial when paired with other energy efficient home improvements such as double glazing and spray foam insulation of the attic or loft.


External Insulation: The Advantages

External insulation is less disruptive than an internal solution but you may have to cut your gas or electricity for the building period.

You won’t loose any space in your home.

The appearance of your external walls can be improved because you can choose from a wide variety of finish types. For example, it can be smooth or textured, painted, tiled, etc. It can also be faced in wood, aluminium panels, brick, or tiles.

With external wall insulation, your home will become more weather resistant and soundproof.

The draughts in your house will be reduced and you will have an improved building seal.

Because insulating material fills all the gaps in the building seal, it lowers the risk of getting condensation and mould inside the walls.

The Disadvantages

There is no getting around it, external wall insulation is expensive. Therefore, the best way to plan the time for installing it is by combining it with other external work that is necessary for your house. By doing so, you will be able to reduce the cost.

If your house is situated in a terrace, there may be the need for scaffolding as the installers will need easy access to the external walls of your home.

In order to install the external wall insulation, your walls have to be in good condition. Therefore, if your outside walls are old and can’t be repaired, then this type of external insulation won’t be suitable.

Period homes and properties won’t always be suitable and depending on the property there may be regulations protecting the building.

Before installing the external insulation, all of the exterior units such as satellite dishes, pipework, or security lights have to be removed and then replaced, adding to the cost.

The roof eaves and window sills will have to be extended so that they fit the thickness of the exterior wall.

Does External Insulation Need Planning Permission?

According to the national planning site, solid wall insulation does not generally require planning permission if your home’s external appearance does not change. If your house is brick and unpainted, you’ll need to get planning permission to change the color with render. You should probably also consult your local planning authorities if the structure is listed or located in a conservation area.

And after numerous reports form across the country it would seem that there is no consistent approach to how councils determine what is acceptable and what is not, based on our experience installing solid wall insulation across London, so if in doubt, be sure to ask first.

Last Updated on November 6, 2021

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Last Updated on November 6, 2021

Frequently Asked Questions

What is external wall insulation?

A system of thermally insulating material boards that are fastened to the building exterior and finished with a weather-resistant, beautiful render.

What are the quality requirements for solid wall insulation systems?

All manufacturers are certified and accredited to the ISO9001 Quality Management Standard, ensuring that all manufacturing processes are monitored consistently.

Why should I consider external wall insulation?

Poorly insulated buildings can lose up to 35% of their heat via the walls. External wall insulation greatly lowers heat loss, resulting in a 25 percent savings in annual fuel expenses. External wall insulation also protects the structure of the building, prevents degradation, and eliminates thermal bridging and condensation issues. Newbuild In the case of new construction, EWI systems are the most cost-effective approach to meet current and future thermal performance criteria for building codes, resulting in an internal environment with low temperature changes and low heating needs.

Is it possible that external wall insulation will be unsightly?

Not at all. External wall insulation systems come in a variety of aesthetic finishes that significantly improve a building’s appearance. All detailing difficulties can be dealt with in an effective and visually appealing manner thanks to a wide choice of trims and accessories.

What types of structures can benefit from external wall insulation?

Almost every sort of home or commercial property will feel the benefit, whether it’s a new build (from steel frame to solid masonry) or a renovation (traditional and non-traditional house types).

Is it environmentally friendly to insulate external walls?

Yes. The ISO14001 Environmental Management Standard is used to produce and independently audit the majority of solid wall insulation systems. CFC and HCFC-free insulation materials are used in external wall insulation systems.


Author: Indra Gupta

Indra is an in-house writer with a love of Newcastle United and all things sustainable.

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