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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.
Claim GBIS grants.
Great British Insulation Scheme ends March 2026 — last chance for fully-funded loft and cavity wall.
✓ 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.
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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
The Great British Insulation Scheme (GBIS) ends 31 March 2026. £1 billion programme. Loft and cavity wall insulation free or heavily subsidised for qualifying UK households. After GBIS: ECO4 only until 31 Dec 2026, then Warm Homes Plan from 2027. Expect to pay £0–£1,500 for UK GBIS-funded insulation.
What Does the Work Involve?
TrustMark or PAS 2030 installer. Free home assessment. Loft insulation top-up to 270mm. Cavity wall insulation. Some flat roof and underfloor. EPC D-G properties priority. Council Tax Band A-D eligibility.
Typical Costs
| Item | Low (£) | High (£) | Notes |
|---|---|---|---|
| Loft insulation full GBIS | 0 | 0 | Free for qualifying |
| Cavity wall GBIS | 0 | 0 | Free for qualifying |
| Loft top-up market rate | 300 | 900 | Without GBIS |
| Cavity wall market rate | 500 | 1,500 | Without GBIS |
| Underfloor insulation | 1,500 | 4,000 | Suspended timber |
| External wall insulation | 8,000 | 20,000 | Not in GBIS scope |
| Annual energy saving estimate | 200 | 500 | Per year heating |
UK Regulations
GBIS (Great British Insulation Scheme) March 2023 to 31 March 2026. ECO4 to 31 Dec 2026. Warm Homes Plan from 2027 (£13.2bn). PAS 2030/2035 retrofit standards.
Frequently Asked Questions
When does GBIS end?
31 March 2026 strict deadline. Works must complete by then.
Eligibility criteria?
Council Tax Band A-D in England, A-E Scotland/Wales. EPC D-G rated. Or benefits-receiving household.
What replaces GBIS?
ECO4 continues until 31 Dec 2026. Warm Homes Plan from Jan 2027 — £13.2bn budget.
How long install takes?
Loft: 2-4 hours. Cavity wall: 4-8 hours typically. Survey to install 4-8 weeks.
Apply directly?
Through approved installers. Ofgem-registered. Free home survey first.
Annual saving worth it?
£200-£500/year heating saving. Plus EPC rating boost helps MEES C 2030 compliance.
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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