Internal Wall Insulation UK

What is internal wall insulation?

Internal wall insulation is a great way to improve your home’s energy efficiency. By adding an insulating layer to the inside of your existing walls. This can be done by either attaching rigid insulation boards directly to the wall. Or by building a stud wall filled with insulation material. Once the insulation is in place, a layer of plasterboard is added to create a smooth surface that’s ready for painting or wallpapering. This method is especially useful for homes in protected or conservation areas. Because it boosts energy efficiency without changing the external appearance of the building.

Why Choose Internal Wall Insulation in 2025?

Compared to external wall insulation, internal wall insulation can be up to 50% less expensive, making it a more economical choice.
The typical price per square foot is between £40 and £50.
It provides long-term energy savings and has a 25-year lifespan when placed correctly.
It can raise the value of your house by as much as 14%.
It’s ideal for homes in protected or conservation areas. Because it improves energy efficiency without altering the outside appearance.

Application Process

Applying for a Internal Wall Insulation grant is simple. Check eligibility, submit your application, and enjoy energy-efficient home improvements for free!

Check Your Eligibility

Submit the application form

Installation

Waiting for permission and installation of the free air source heat pump.

Schedule your survey with us

Confirm the details over the phone and schedule a free survey.

What is the cheapest way to insulate internal walls?

Thermal lining paper: Thermal lining paper: Insulating wallpaper improves your home's thermal efficiency and is simple to apply. Depending on the brand, it costs about £10/m² and only needs adhesive and simple tools.
Insulated plasterboard: Insulated plasterboard: allows you to finish and insulate in a single step. Ideal for do-it-yourself insulation jobs, all you need to do is glue or screw, seal the connections, and you're done.
Loose-fill insulation for stud wall: Loose-fill insulation for stud walls: such as fiberglass or cellulose (costing around £10 per square metre). Can be used to insulate stud walls in your home. Improved energy efficiency and even coverage are guaranteed by professional installation.

Internal wall insulation regulations in the UK

Thermal Performance: Thermal Performance: In order to meet UK rules, insulation must have a U-value of 0.3 W/m²K or less.
Insulation Thickness: Insulation Thickness: To satisfy thermal performance requirements, a thickness of about 100 mm is usually advised.
Ventilation: Ventilation: Sufficient ventilation needs to be kept up. To stop moisture buildup, install mechanical systems or air bricks.
Moisture Control: Ventilation: Sufficient ventilation needs to be kept up. To stop moisture buildup, install mechanical systems or air bricks.
Fire Safety: Control of Moisture: Prior to installation, make sure the walls are dry. To avoid condensation, use vapour barriers.
Fire Safety: Fire Safety: Make use of insulating materials that are fire-retardant and adhere to UK safety regulations.

The best insulation for walls inside

Rigid foam boards

PIR, XPS, and EPS rigid foam boards provide superior insulation, have high R-values, and are simple to install. They efficiently lower heat loss and increase energy efficiency, making them perfect for homes with solid walls.

Fibreglass

Up to 540°C, this reasonably priced insulation effectively retains heat and withstands fire. But because it isn’t airtight, moisture may seep in, decreasing effectiveness and increasing the risk of mold growth.

Cellulose

Made from recycled paper, cellulose insulation is an affordable, environmentally responsible option that provides an airtight performance and a high R-value. Because of moisture concerns, it is not advised for stone walls; it works best for dry interior walls.

Spray foam

Both open-cell and closed-cell spray foam insulation provide excellent soundproofing, moisture resistance, and thermal performance.

How to insulate internal walls

Assess the condition of your walls

Look for any indications of damage or moisture on your walls. To guarantee insulation's efficiency and avoid further complications, all faults must be fixed before installation.

Understand the dew point

The point at which air saturates and condensation develops is known as the dew point. This temperature has the potential to cause damage and dampness to your walls. Long-term house protection and condensation prevention are achieved by using vapour barriers and other measures.

Remove fixtures

Remove fixtures such as shelves, radiators, outlets, and skirting boards before insulating. Switch off the electricity, empty radiators, and carefully remove everything. Before plasterboard and insulation are added, fix damaged walls and mark hardware for reinstallation.

Address potential thermal bridges

Determine the typical locations for thermal bridging, such as pipes, windows, doors, and floor gaps. Before the main insulation starts, proper insulation in these areas helps maintain a continuous thermal envelope and minimizes heat loss.

ECO4 Scheme Eligibility Criteria

To be eligible for a free boiler grant, you must receive any of the following benefits: