Internal Wall Insulation Grants

Read What Carbon Rewind Have to Say About Internal Wall Insulation Grants in 2022

We spoke to Carbon Rewind, a TrustMark Registered Installer who install Internal Wall Insulation grants throughout England. They are energy-efficiency and grant experts and have kindly provided this content. Read on to find out everything you need to know about getting an internal wall insulation grant in 2022.

1. Is internal wall insulation right for your home?

Internal wall insulation needs to be carefully considered before installation, but it can help to make big savings on heating bills.

Internal wall insulation is a route to consider for improving the thermal properties of solid-walled homes. These tend to be solid stone or brick properties built before the 20th century, without a cavity wall and therefore no option of installing cavity wall insulation. 

Internal wall insulation will always be free under the ECO scheme via Carbon Rewind but not all properties will qualify.

While making savings on your heating bills free of charge may seem like a no-brainer, internal wall insulation will fundamentally change the fabric of your home, and therefore needs to be carefully considered. 

Here’s everything you need to know, including the pros and cons of installing internal wall insulation.

2. What is internal wall insulation?

Internal wall insulation involves the application of insulation to the interior face of external walls in order to improve the thermal performance of the property. 

Internal wall insulation can, however, be disruptive and require the removal and re-fixing of items such as switches and wall heaters, so you need to be sure it is the best insulation solution for your home. 

Creating an airtight layer is vital, so awkward areas, such as reveals and floor voids, require particular care.

3. What is the cost of internal wall insulation?

According to Carbon Rewind, the generally accepted cost for internal wall insulation is between £50 and £60/m2 with additional detailing and complexities increasing the cost.BOR COS

The Energy Saving Trust say that for a typical 3-bedroom, semi detached property in the UK the typical installation costs* of solid wall insulation would be:

Internal wall insulation: around £8,200

*Based on a typical 3-bedroom, semi-detached house in Great Britain

However, before paying full price for internal insulation it is worth checking if you qualify for an ECO grant as any internal wall insulation carried out under the ECO scheme will be for free. At the moment electric properties qualify for grants but from April 2022 the most inefficient homes with an EPC rating of D, E, F or G might also be eligible.

4. How is internal wall insulation installed?

The method used by Carbon Rewind has been fully certified with the BBA and the products are provided by Provincial Seals. The 62.5mm insulated plasterboard is pre fitted with a vapour barrier.

If the wall is relatively flat and in good condition, this can be an effective, quick method. Boards can be glued directly to the wall with an adhesive specific for the purpose or dot and dab. Gaps between boards, at the ceiling and floor edges, should be filled with mastic and taped over before plaster skimming to ensure continuity of the vapour barrier.

Ensuring a continuous, unperforated vapour barrier is the only effective way of dealing with a dew point that occurs in the wall.

Following the installation the property will be left plastered and ready for redecoration, Carbon Rewind will not undertake the redecoration of the treated elevations unless this is agreed beforehand, in which case there would be an additional cost for the service.

5. Common complications during the installation process?

Plug sockets – When installing insulated plasterboard to the external elevations the cables behind lights and plugs will need to be extended which also means that new socket boxes will be installed during the installation process.

Room heaters – Any heater on the external wall of the property will need to be removed to allow the elevation to be insulated and plastered. Following the installation, the heater will be remounted and connected.

Flooring – Flooring from the front door and in the areas of work will be always protected. Carpet will need to be trimmed back to accommodate the insulation being installed.

Coving – If the property has coving at present there is a strong chance, we will not be able to replace this like for like. This leaves us with two options, we can mitre the insulation into the curve of the existing coving which will reduce the visible area of the coving or alternatively we can provide new coving to the insulated elevations only, however we will not be able to guarantee that this matches the existing coving in the room.

Skirting – This will be carefully removed from the elevations we are going to be insulating. Our operatives will take care when removing these however we can not guarantee that damage will not be caused during the removal process. Following the installation, we will re install the existing skirting if it is in a good state of repair, however if the skirting is damaged during the removal process, we will endeavour to provide a replacement skirting as close to the existing skirting as possible.

Window Sills – These will need to be extended to protrude past the insulation, the method for completing this is to install PVC overboard over the top of the existing timber sills.

ECO scheme compliance rules – Due to Ofgem guidelines, under the ECO scheme all internal walls that are exposed to the outside air must be insulated. Therefore, we can only proceed with the works if we are able to insulate 100% of the property. There is only one exception to this – as kitchens and bathrooms normally have many units on the wall, as well as other obstructions (such as showers and stoves), the ECO scheme allows us to not insulate these rooms if we unable to. A trade-off is that we will install a mechanical extraction fan, as well as a heating source of some kind, in each of these rooms.

6. Does internal wall insulation cause damp?

The dew point is the point where air meets a temperature that causes the moisture to condense out as water. Internal wall insulation will tend to keep the wall at external ambient temperature and thereby draw the dew point towards the internal surface. 

If the dew point is too close to the internal surface of the existing wall, moisture can be absorbed by the insulation and appear as damp patches on the plasterboard.

 To help prevent damp penetration, a vapour control layer is pre installed to the wall. The internal surface of an insulated wall will tend to be warmer, reducing the likelihood of condensation forming, but there will be areas – such as where an external wall meets an internal wall – that remain cold. 

There is a distinct risk of condensation forming in those areas, typically in high-level corners. Overcoming this typically means extending the insulation to cover that cold bridge.

7. What are the building regulations for internal wall insulation?

The Building Regulations stipulate certain requirements when it comes to airtightness and heat loss that need to be achieved in order for your home to be compliant.  

The U value of a material is the rate at which heat (in watts) is lost through each square meter of the surface. A lower figure means better thermal performance.

  • An uninsulated cavity wall will have a U value of around 1.5W/m2 and there will also be a relatively high level of cold bridging due to the cavity ties
  • A solid 225mm brick wall will be around 1.9W/m2
  • A solid stone wall will be around 1.7W/m2 to 1.4W/m2 (depending on the thickness)
  • Current Building Regulations require a maximum U value of 0.3W/m2 and realistically 0.2W/m2. Achieving that U value for solid walls will mean installing at least 100mm of rigid insulation (Celotex, Kingspan or similar)


It has been well established that improving airtightness has a greater impact on heat loss than insulation. The solid elements of the wall will naturally be fairly airtight — but it is the gaps, cracks and penetrations that can be problematic.

These tend to occur as much in awkward places, such as floor/ceiling voids, below the ground floor, the first floor ceiling, as on the accessible areas of the wall. The insulation applied to the wall can form the airtight barrier, but the benefit will be reduced by up to 50% if the gaps, cracks and penetrations are not also dealt with.

8. Who is eligible for internal wall insulation grants?

The scheme is open to low-income homeowners in the UK, both private and social housing. There are restrictions on who can apply for a grant, and you must own your home and live in it as your main residence and either claim benefits, have a health condition made worse by the cold or have a low-income or vulnerable status. The insulation must be installed by an approved TrustMark Registered contractor. To explore grant options you can use our quick grant checker to get an immediate result regarding eligibility.

9. How to apply for an internal wall insulation grant?

The good news is that there are grants available to help homeowners pay for the cost of internal wall insulation. The homeowner needs to meet Energy Company Obligation rules and currently to be eligible you will need to have a limited income or you’ll need to have received certain benefits in the last 18 months, or you will need to be vulnerable to the effects of living in a cold home. You can search contact a Registered Installer like Carbon Rewind or search the TrustMark database to make sure you connect with the very best internal wall insulation installers. You can also check your eligibility on the Energy Saving Genie grant checker here >

So, is internal wall insulation the right choice for your home? The short answer is, it depends.

There are many factors to consider when making this decision, such as your circumstances and the type of property you live in. That’s why we always recommend getting a professional assessment from an expert installer like Carbon Rewind. If you want to jump straight in and apply for internal wall insulation, head over to our website where you can find out everything you need to know. We also have a handy grant application tool that makes it easy for homeowners to apply for financial assistance with installing internal wall insulation. Visit www.energysavinggenie.co.uk today to get started! Once you’ve applied you’ll be connected with a TrustMark registered installer like Carbon Rewind who will take care of the application process from start to finish.

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