An insulation installer specialises in fitting thermal and acoustic insulation to improve building performance. The trade covers a wide range of products and installation methods including mineral wool in loft and cavity, rigid insulation boards for walls and floors, spray foam for roofs and hard-to-treat spaces, and external wall insulation (EWI) systems. Insulation work must comply with Building Regulations Part L (conservation of fuel and power). Many installations are eligible for government grants under the Great British Insulation Scheme or ECO4, and grant-funded work must be carried out by TrustMark-registered installers with PAS 2030 or PAS 2035 certification.
What they do
- Loft and roof insulation installation
- Cavity wall insulation injection
- Solid wall insulation - internal and external
- Underfloor insulation - suspended and solid floors
- Flat roof insulation
- Acoustic insulation between floors and walls
- Spray foam insulation for roofs and hard-to-treat areas
- Pre-installation surveys and post-installation certificates
When you need one
Insulation is one of the most cost-effective improvements you can make to an existing home. Check grant eligibility before commissioning work.
Typical costs (UK, 2025)
| Job type | Typical cost |
|---|---|
| Loft insulation (per property) | £300 - £600 |
| Cavity wall insulation (semi-detached) | £400 - £1,000 |
| Internal wall insulation (per sq m) | £50 - £100/sq m |
| External wall insulation (per sq m) | £80 - £150/sq m |
| Underfloor insulation (suspended floor) | £1,000 - £3,000 |
| Acoustic floor treatment (per sq m) | £20 - £60/sq m |
Government grants can significantly reduce or eliminate costs for eligible households. Check eligibility via the Great British Insulation Scheme at gov.uk before commissioning work at full price.
Qualifications to look for
TrustMark-registered installers have been vetted for technical competence and customer service. TrustMark registration is required for all grant-funded energy efficiency work under the Great British Insulation Scheme and ECO4.
PAS 2030 is the installation standard for energy efficiency measures. PAS 2035 covers the retrofitting of dwellings as a whole. Both are required for Ofgem-obligated or government-funded insulation work.
NIA membership indicates adherence to the insulation industry's code of practice and technical standards. Find NIA members at nationalinsulationassociation.org.uk.
How to find a reputable insulation installer
Frequently asked questions
What is the cheapest insulation upgrade for a typical UK home?
Loft insulation is typically the cheapest and highest-impact insulation upgrade. The recommended depth is 270mm of mineral wool. Costs range from around £300 for a small property to £600 for a larger detached house. Cavity wall insulation is also relatively inexpensive at £400-1,000 for a typical semi-detached house. Grants may be available through the Great British Insulation Scheme or ECO4.
Is cavity wall insulation right for my property?
Cavity wall insulation is suitable for most properties built from around 1930 onwards with a standard 50mm or wider unfilled cavity. It is not appropriate for properties in high-exposure wind-driven rain zones, properties with cavity drainage systems, or walls with defective pointing. A TrustMark-registered installer will survey the wall first using a borescope to check the cavity is clear before proceeding.
Can I get a grant for insulation?
Yes - the Great British Insulation Scheme and ECO4 (Energy Company Obligation) provide grants and subsidised insulation for eligible households. Eligibility depends on household income, EPC rating and whether you own or rent the property. Your energy supplier or the government's Help for Households scheme can advise on eligibility. TrustMark-registered installers can carry out grant-funded work.