Internal Wall Insulation

Why Choose Internal Wall Insulation?

Internal wall insulation is cost-effective and can be up to 50% cheaper than external wall insulation.
The typical cost of internal insulation ranges from £40 to £50 per square metre.
Properly installed internal wall insulation can last up to 25 years, providing long-term energy savings and increasing the value of your home by up to 14%.
Internal wall insulation is an effective way for homes located in protected or conservation sites to improve energy efficiency without altering the house's external appearance.

What is internal wall insulation?

Insulating your internal walls involves adding a layer of insulation material to the inside of your home’s existing walls. Attach rigid insulation boards directly to the wall or build a stud wall filled with insulation for effectiveness. Once insulated, apply smooth plasterboard for a finished surface, ready for painting or wallpapering. The method includes several vital layers:

Existing wall surface: The original interior wall is made of brick, stone, or other materials.
Vapour control layer: A layer that prevents moisture build-up, reducing the risk of condensation and dampness.
Plasterboard or internal finish: The final layer, typically plasterboard, provides a smooth, decorative surface.

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: Easy to install and great for DIY, insulating wallpaper adds thermal efficiency to your home. It costs around £10/m², depending on the brand, and requires only basic tools and adhesive.
Insulated plasterboard: Install insulated plasterboard directly on internal walls—combining insulation and finish in one step. Simply glue or screw, seal the joints, and you're done—perfect for DIY insulation projects.
Loose-fill insulation for stud wall: If your home has stud walls, you can insulate them using fibreglass or cellulose, costing around £10/m². Professional installation ensures even coverage and improved energy efficiency.

Internal wall insulation regulations in the UK

Thermal Performance: Insulation should achieve a U-value of 0.3 W/m²K or lower to comply with UK regulations.
Insulation Thickness: Around 100mm is typically recommended to meet thermal performance standards.
Ventilation: Adequate ventilation must be maintained. Add air bricks or mechanical systems to prevent moisture buildup.
Moisture Control: Ensure walls are free from damp before installation. Use vapour barriers to prevent condensation.
Fire Safety: Use fire-retardant insulation materials that meet UK safety standards.

Best insulation for interior walls

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Rigid foam boards

Rigid foam boards like PIR, XPS, and EPS offer excellent insulation with high R-values and easy installation. Ideal for solid wall homes, they effectively reduce heat loss and boost energy efficiency.

Fibreglass

This affordable insulation traps heat well and resists fire up to 540°C. However, it isn’t airtight and may absorb moisture, reducing efficiency and risking mould.

Cellulose

Cellulose insulation is a cost-effective, eco-friendly solution made from recycled paper, offering strong R-value and airtight performance. Best for dry internal walls, it’s not recommended for stone walls due to moisture concerns.

Spray foam

Spray foam insulation—available in open-cell and closed-cell forms—offers superior thermal performance, moisture resistance, and soundproofing.

How to insulate internal walls

Assess the condition of your walls

Inspect your walls for any signs of dampness or damage. It's crucial to repair any issues before installing insulation to ensure its effectiveness and prevent future problems.

Understand the dew point

The dew point is when air saturates and condensation forms. If your walls hit this temperature, it can cause damp and damage. Using vapour barriers and other solutions helps prevent condensation and protect your home long-term.

Remove fixtures

Before installing insulation, remove fixtures like outlets, radiators, skirting boards, and shelves. Turn off power, drain radiators, and safely detach items. Label hardware for reinstallation and repair wall damage before adding insulation and plasterboard.

Address potential thermal bridges

Identify common thermal bridging areas like windows, doors, floor voids, and pipes. Proper insulation in these spots helps maintain a continuous thermal envelope and reduces heat loss before main insulation begins.

ECO4 Scheme Eligibility Criteria

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

Income-Based Jobseeker’s Allowance (JSA)
Income Related Employment & Support Allowance (ESA)
Income Support (IS)
Pension Guarantee Credit
Working Tax Credit (WTC)
Child Tax Credit (CTC)
Universal Credit (UC)
Housing Benefit
Pension Savings Credit
Child Benefits