Internal Wall Insulation Grants: A Way to Save on Energy Bills in the UK

The internal wall insulation grant has been proven very beneficial as more and more individuals in the UK find themselves searching for long-term methods to make their homes warmer, greener, and cheaper to maintain as energy costs continue to go up. One of the best ways to accomplish this is to insulate the walls inside. This is a good upgrade that makes your home more comfortable and helps the environment by lowering your carbon footprint.

If your walls are not properly insulated, up to 35% of the heat generated by your heating system in your home can escape through areas that are not insulated. This implies that walls allow heat to pass through the most. Insulation on the inside of the walls keeps heat inside in the winter and outside in the summer. That means you spend less on bills and use less energy.

The UK government continues to provide individuals with grants and other help to insulate their homes in 2026. This is part of an effort to lower the country’s CO₂ emissions. Installing insulation on the inside of your walls can help the environment and save you money, regardless of where you live, the age of your building, or how much you want to lower the cost of energy.

This overview will provide you with everything you need to know about insulating your internal walls in 2026 so you can choose the best option for your home’s efficiency and environmental sustainability. It will provide information about how to install it, how much it costs, grants, what is positive and negative about it, and how much carbon dioxide it reduces.

What Is Internal Wall Insulation?

The installation of internal insulation of your external walls is what internal wall insulation means. This prevents heat from passing through the walls, which saves energy and reduces heat loss.

How Internal Wall Insulation Works

The walls in the home are either composed of bricks or insulation boards that have been filled with materials that stop heat inside. Plasterboard is generally applied to provide a smooth, finished surface that is able to be painted or decorated. This is done after putting up a vapour barrier to prevent moisture from building up.

When is internal wall insulation needed?

Insulation for interior walls is most useful when:

• For homes with solid walls that have inefficient cavity wall insulation.
• Conservation areas or listed structures where external renovations are forbidden.
• Homes in cold regions or where energy costs are high.

Installation Methods of Internal Wall Insulation

Direct Wall Insulation: Insulation of rigid foam boards, for example, PIR or EPS, is put directly on the internal wall, depending on circumstances, financial limitations, and available space.

Stud Wall Insulation: A wood or metal frame is built, which is then filled with insulation (which can be fibreglass or mineral wool), plasterboard, and vapour barriers.

 Batten Wall Insulation: To make space for insulation, battens, or wood or metal strips, are attached to walls. There are two categories:

1. Cold batten
2. Warm batten

Insulating Plaster: An environmentally friendly method involving the use of thermally responsive breathable plaster.

Best Materials for Internal Wall Insulation

Material	R-Value	Cost per m²	Moisture Resistance	Eco-Friendliness
Rigid Foam Boards	4.0–6.0	40–60	High	Moderate
Mineral Wool	3.0–4.5	30–45	Good	High
Cellulose	3.5–4.0	25–40	Good	Very High
Cork Boards	3.0–4.0	50–70	High	Very High
Sheep Wool	3.0–3.8	40–60	Good	Excellent

Internal Wall Insulation Grants in the UK

Getting your internal walls insulated can be costly for most UK households; hence, the UK government has initiated free government internal wall insulation grants to help low-income and vulnerable households get grants to insulate their internal walls. There are a number of free internal wall insulation grants available for homeowners to increase their energy efficiency:

1. Great British Insulation Scheme (GBIS)
2. Warmer Homes Scotland
3. Affordable Warmth Scheme (Northern Ireland)
4. The Energy Company Obligation (ECO4 Scheme)

Regulations & Building Standards for Internal Wall Insulation

Before starting to insulate your home’s internal wall, these are some of the main UK building regulations you should keep in mind.

• Walls must meet a U-value target of 0.30 W/m²K or below.
• Make sure the wall is dry, and always install a vapour barrier.
• Use extractor fans or air bricks to maintain the air flow.
• Use approved insulating boards according to installation guidelines for fire safety.
• Before conducting interior changes, get planning approval.

Pros and Cons of Internal Wall Insulation

Pros:

• Decreases heat loss and reduces energy bills
• Minimises annual carbon dioxide emissions by up to 2 tonnes.
• Boosts the value of property by up to 14%.
• Suitable for classic or conservation properties.

Cons:

• Space area decreases slightly (by up to 10 cm per wall).
• Installation could result in interruptions.
• It requires it to be installed properly to avoid moisture.
• It can be required to reinstall the sockets and radiators.

Benefits of Installing Internal Wall Insulation (IWI)

1. Internal wall insulation makes your home warmer in the winter and cooler in the summer by stopping more and more heat.
2. You can minimise your carbon impact by up to 2 tonnes a year if you heat your home with less energy.
3. Insulated walls maintain the temperature in your home balanced by preventing noise and cold spots.
4. IWI makes homes use less energy, and it is a known fact that homes that use less energy are more likely to be sold for a higher price.
5. Internal wall insulation is ideal for homes built before the 1920s or for homes that cannot get external wall insulation.
6. Your home will become more peaceful and quiet as insulated walls naturally block outside noise.
7. If you install it properly, interior wall insulation can last for 40 years or more with hardly any maintenance needed.

FAQs