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01 · Ask
Cavity, loft or solid wall?
Different house ages, different methods. Describe the property and the AI tells you which insulation type and grants apply.
Insulate your home.
Loft, cavity, underfloor or solid-wall — sized to your home and grant-eligible where applicable. Pays back in 2–7 years.
✓ Updated May 2026✓ Free quotes✓ Vetted pros
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Hire an insulation installer. Surveyed, grant-checked, sealed.
Read the brief on cavity surveys, grants and PAS 2035 — then let Three local installers quote.
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02 · Read the brief
Walk in informed
U-values, ECO4 eligibility, PAS 2035, CIGA guarantee, breathability rules. Know what to ask for.
60 seconds
03 · Compare
Compare 3 installer quotes
Three local installers quote on the same spec — survey, depth, materials, guarantee — so the warmth is real, not on paper.
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Top tips
Hiring a insulation, without the regret.
Four moves that separate a smooth job from a nightmare.
Cavity walls need a survey first.
Some cavities can't be filled — too narrow, exposed walls, wind-driven rain zones. A reputable installer surveys before quoting; cowboys don't.
Loft insulation: 270mm is current standard.
Building Regs require 270mm of mineral wool (or equivalent). Older lofts often have 100mm or less. Top-up is cheap and pays back in a year.
Don't trap damp in solid walls.
External or internal solid-wall insulation can trap moisture. PAS 2035 retrofit assessment first — skip this and the wall rots from the inside.
Check grant eligibility before paying.
ECO4 covers full insulation costs for qualifying households. Check before paying — many installers won't mention it because it caps their margin.
Costs & timeline
Know what it costs. Know when it ends.
Indicative UK ranges and what affects price.
Cost range
By job type
Inc. VAT · 2026
Source: NMT quotes
Source: NMT quotes
Loft insulation (top-up)3-bed house
£250–£600
Cavity wall insulation3-bed
£500–£1.5k
External wall insulation (per m²)
£100–£180/m²
Internal wall insulation (per m²)
£60–£120/m²
Underfloor insulation (suspended)
£600–£2.5k
Floor insulation (solid floor)
£80–£160/m²
!
Quote spread is typically ± 18% — always get 3 quotes.
At a glance
Infographic · VideoThe Insulation briefing.
Infographic
Insulation quick-view
Video guide
Insulation explained
UK insulation upgrades typically pay back in 2–7 years on heating bills. Choosing the right type depends on your wall construction (cavity vs solid), loft access, and floor type.
Upgrade options ranked by payback
| Type | Cost | Annual saving | Payback |
|---|---|---|---|
| Loft (270mm) | £450–£900 | £140–£260 | 2–4 yrs |
| Cavity wall | £900–£1,800 | £200–£350 | 4–6 yrs |
| Solid wall (internal IWI) | £5k–£12k | £300–£600 | 10–20 yrs |
| Solid wall (external EWI) | £10k–£20k | £300–£600 | 15–25 yrs |
| Underfloor (suspended timber) | £900–£2,400 | £60–£140 | 10–15 yrs |
Grants
ECO4, GBIS and local-authority schemes can cover 30–100% of loft and cavity wall costs for eligible households. Check your eligibility before paying — most installers will check for you free.
What to check
U-value before and after, BBA certification on the product, and that the installer is registered with a CIGA, GDGCC or KIWA scheme for the warranty.
This guide was written with AI assistance and is intended for general information only. Prices are estimates based on UK averages and may vary by region. Always get at least three quotes and consult a qualified professional before starting any work.
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