HOW TO HIRE · TRADES & CONSTRUCTION

How to hire a cavity wall insulation installer in the UK
The checks, the questions and the paperwork.

Cavity wall insulation is notifiable in England unless a scheme installer self-certifies it. The suitability questions, VAT, grants and the paperwork.

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THE 60-SECOND VERSION

Hiring a cavity wall insulation installer in five steps

  1. Check the installer's schemegov.uk lists Blue Flame, CERTASS, Certsure, IAA and NAPIT as schemes for cavity walls.
  2. Ask whether your walls are suitableCavity width, exposure to driving rain, and the state of the brickwork and pointing.
  3. Compare the materialBead, wool or foam, with the reasons for the choice.
  4. Check VAT and grants0% VAT on the installation; Home Energy Scotland or Nest if you qualify.
  5. Keep the certificate and guaranteeThe compliance certificate and any insulation guarantee, with the deeds.

BEFORE YOU BOOK

Check before you book

Competent person scheme for cavity wall insulation

gov.uk's current list of competent person schemes for cavity walls in an existing building is Blue Flame Certification, CERTASS, Certsure, the Installation Assurance Authority and NAPIT. An installer on one of them self-certifies the cavity wall insulation under the Building Regulations in England; otherwise building control must be notified first.

Ask which scheme the installer is on and check it with the scheme before you book. gov.uk →

Notifiable work (England)

gov.uk lists cavity and solid wall insulation among the home improvements that are notifiable building work in England, with a certificate of compliance from the scheme expected within 30 days of completion.

If the certificate for the cavity wall insulation has not arrived, contact the installer's scheme. gov.uk →

TrustMark

TrustMark is the Government Endorsed Quality Scheme for work in and around the home; it is voluntary and registration is trade by trade, so check it covers cavity wall insulation.

Search the business on TrustMark for insulation. trustmark.org.uk →

Insurance and trader status

Ask who insures the trader doing the cavity wall insulation and for how much; public liability is standard. The Consumer Rights Act 2015 covers the cavity wall insulation when the provider is a trader, and a contract made off-premises or online can usually be cancelled within 14 days under the Consumer Contracts Regulations 2013 — less what was done if you asked for an early start, and not at all for goods made to your specification.

Ask for proof of insurance for the cavity wall insulation; the trader and ID-checked badges are on the Locufy profile.

VAT

Installing cavity wall insulation in a home is zero-rated (0%) until 31 March 2027, then 5% from 1 April 2027; the same material bought without installation, or fitted in a hotel or other commercial building, is standard-rated, and an installer over the £90,000 threshold must still register and show the VAT, at 0%, as its own line.

Ask for the VAT number and check the cavity wall quote shows 0% on the installed insulation and that nothing on it is charged at the standard rate. gov.uk →

“Is my wall suitable for cavity wall insulation?”

A good answer: A survey answer, not a sales one: cavity width, exposure to wind-driven rain, the state of the brickwork, and any existing fill.

“Which competent person scheme will certify the cavity wall insulation?”

A good answer: A named scheme from gov.uk's list and a compliance certificate after the job.

“Bead, wool or foam — and why?”

A good answer: A reason based on your walls; the installer should say why one suits them.

“How will you check every part of the cavity is filled?”

A good answer: A drilling pattern that covers the walls, with checks around openings and at corners.

“What happens to the air bricks and vents?”

A good answer: Ventilation kept clear; air bricks sleeved or protected so the fill does not block them.

“Is there a guarantee for the cavity wall insulation?”

A good answer: A written guarantee and who backs it, with its length.

“Am I eligible for a grant?”

A good answer: In Scotland, the Home Energy Scotland grant if the EPC or a Home Energy Scotland report recommends it; in Wales, Nest if you qualify.

Getting the quote right

  • Wall area and the insulation material named
  • Survey findings: cavity width and condition
  • Making good the drill holes
  • Who actually attends — the surveyor and the installers who drill and fill, employed or subcontracted — and the business's VAT number, with VAT at 0% on the installation shown as its own line
  • The competent person scheme, certificate and guarantee

Walk away if

  • No survey of the walls before quoting
  • Cannot name a scheme from gov.uk's list
  • Adds standard-rate VAT to insulation blown into your cavity walls
  • Cold call promising a 'free government grant' with no details
  • No guarantee in writing
LOW
£1,000
TYPICAL
£2,500
HIGH
£4,600

What a cavity wall insulation installer costs: £1,000–£4,600 per job

Cavity wall insulation is priced per job, mostly by the wall area of the house; the material and access to every elevation also move it, and VAT is 0% on an installed home job. Cavity Wall Insulation price guide →

Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.

KNOW WHAT TO LOOK FOR? NOW FIND ONE

Cavity wall insulation installers near you, with the badges that matter shown

ID checked, trader status and one score from every review — on the card, before you message anyone. Nearest first. No account needed to look.

Or post the job free and let them come to you.

  1. SurveyThe installer checks cavity width, exposure, brickwork and existing fill.
  2. PrepareAir bricks and vents protected; drilling pattern marked.
  3. Drill and fillHoles drilled through the mortar joints and the cavity filled.
  4. Check and make goodCoverage checked; holes filled to match.
  5. CertifyThe scheme notifies building control and sends the compliance certificate; the guarantee is issued.

Cavity wall
Two leaves of brick or block with a gap between them.
Blown fibre / bead
Insulation blown into the cavity through drilled holes.
Driving rain exposure
How hard wind-driven rain hits the walls, which affects suitability.
Air brick
A vented brick that ventilates under floors.
Compliance certificate
The scheme's confirmation that the work meets the Building Regulations.
EPC
Energy Performance Certificate, which recommends improvements.

AFTER

When the job is done

Keep the certificate and guaranteeThe compliance certificate from the scheme and the insulation guarantee; a buyer's solicitor will ask.
Check the drill holesFilled and coloured to match the mortar.
Watch the inside wallsOver the first winter, any new damp patch is a reason to call the installer back.
Rate the workOnly booked jobs can be reviewed on Locufy, so yours carries weight; if the cavity wall insulation falls short, use the make-it-right step first and the provider is asked to fix it before the review is published.

MONEY BACK

Grants that may apply

Public schemes that can pay towards cavity wall insulation in Scotland and Wales. Check eligibility and apply before work starts.

SCOTTISH GOVERNMENT (HOME ENERGY SCOTLAND) · GRANTVerified 16 Oct 2026

Home Energy Scotland grant and loan

up to £7,500 grantClean heating such as a heat pump: grant up to £7,500 plus an optional interest-free loan up to £7,500. Energy efficiency such as insulation: grant up to 75% of the cost, capped at £7,500, plus an optional loan up to £7,500. Rural and island homes can get up to £1,500 more on each.

Who: homeowners in Scotland; landlords, businesses and developers cannot apply

  • the improvement must be recommended in the home's Energy Performance Certificate, Home Energy Improvement Report or Home Renewable Selector Report
Official details on mygov.scot →
WELSH GOVERNMENT · GRANTVerified 16 Oct 2026

Nest

free improvementsThe Welsh Government describes the improvements as free to eligible households; no cash amount is published on the page.

Who: owner-occupiers and private tenants in Wales (not council or housing association tenants)

  • a means-tested benefit (such as Universal Credit or Pension Credit) or a low household income
  • EPC rating of 54 (E) or below, or 68 (D) or below where someone has an eligible health condition
Official details on gov.wales →

Schemes change. The amounts above were checked on the dates shown; the official page is the one that counts.

STEP 1Start with the installer, in writingSend the installer a short, dated account of the problem with the cavity wall insulation and the fix you want. Section 49 of the Consumer Rights Act 2015 implies reasonable care and skill into the contract, and section 54 gives you repeat performance or a price reduction when it is missing.
STEP 2Use Locufy's make-it-right stepRate the cavity wall insulation under four stars and you are asked whether to send it to the provider first; we follow it through. Then the review goes up.
STEP 3Certification or grant problemsIf the cavity wall insulation was MCS certified and is faulty, MCS takes complaints about its certified installers; grant problems go to Ofgem, which runs the Boiler Upgrade Scheme. For a dispute about the cavity wall insulation with the trader, Trading Standards is reached through the Citizens Advice consumer helpline on 0808 223 1133 in England and Wales, Advice Direct Scotland on 0808 800 9060, or Consumerline on 0300 123 6262 in Northern Ireland.
STEP 4Money still in disputeIf the cavity wall insulation is still not settled, you can claim without a solicitor: the small claims track takes claims up to £10,000 in England and Wales, simple procedure up to £5,000 in Scotland, and the small claims court up to £5,000 in Northern Ireland.

Hiring a cavity wall insulation installer: questions people ask

In England it is notifiable work: an installer on an authorised competent person scheme self-certifies it, or building control is notified before work starts.

gov.uk lists Blue Flame Certification, CERTASS, Certsure, the Installation Assurance Authority and NAPIT for cavity walls in existing buildings.

£1,000–£4,600 a job, typically around £2,500. House size decides most of it; the material and access to every wall also move it. The Cavity Wall Insulation price guide goes through it line by line; type your postcode above for cavity wall insulation installers in your area.

Installed in a home, it is zero-rated until 31 March 2027, then 5%.

In Scotland, the Home Energy Scotland grant can cover up to 75% of an energy efficiency improvement, capped at £7,500, if your EPC or a Home Energy Scotland report recommends it; in Wales, Nest offers free improvements to eligible households.

On an unsuitable wall it can; that is why the survey matters more than the price.

MORE GUIDES

More hiring guides in trades & construction

How to hire: Insulation InstallerHow to hire: Loft InsulationHow to hire: Damp ProofingHow to hire: RenderingHow to hire: CladdingHow to hire: BuilderHow to hire: Dry LiningHow to hire: Window & Double Glazing InstallerAll 701 hiring guides →

Cavity wall insulation installers near you

Cavity wall insulation installers in LondonCavity wall insulation installers in ManchesterCavity wall insulation installers in BirminghamCavity wall insulation installers in GlasgowCavity wall insulation installers in BelfastAll cavity wall insulation installers on Locufy →

Sources — checked October 2026

  1. gov.uk — competent person schemes: current schemes and the work they cover
  2. gov.uk — building work, replacements and repairs to your home (England)
  3. gov.uk — VAT on energy-saving materials and heating equipment (Notice 708/6)
  4. TrustMark — the Government Endorsed Quality Scheme
  5. mygov.scot — Home Energy Scotland grant and loan
  6. gov.wales — free home energy efficiency improvements from Nest: eligibility
  7. nidirect — energy saving grants in your area
  8. Consumer Rights Act 2015, section 49 — reasonable care and skill
  9. Consumer Rights Act 2015, section 54 — what you can ask for when a service falls short
  10. Consumer Contracts Regulations 2013, regulation 30 — the 14-day cancellation period
  11. Consumer Contracts Regulations 2013, regulation 28 — contracts the cancellation right does not cover
  12. Consumer Contracts Regulations 2013, regulation 36 — services started within the cancellation period
  13. Civil Procedure Rules Part 26 — the small claims track limit (England and Wales)
  14. Scottish Courts and Tribunals — making a claim under simple procedure
  15. nidirect — the small claims process (Northern Ireland)
  16. Energy-saving materials and heating equipment (VAT Notice 708/6) — 2.1 Zero-rated installations; 2.10 Insulation
  17. GOV.UK — VAT rates
  18. GOV.UK — Register for VAT: when to register