Can cavity wall insulation be removed? Yes. A specialist drills small holes in the mortar joints and vacuums the fill out, usually in one to three days. Checkatrade's July 2026 guide puts cavity wall insulation removal at about £21.50 per m², or £1,680–£2,520 for a whole house (average £2,100); urea formaldehyde foam adds around £500–£1,000. Before you pay anyone: if your insulation has a CIGA guarantee, CIGA says any remedial work it agrees is needed is carried out free of charge, and pulling the insulation out first can void that guarantee. How to claim ↓Last checked: 30 October 2026
(Checkatrade, July 2026)
transfers to new owners
rectification value
Cavity wall insulation problems: the signs it has failed
Most cavity wall insulation causes no trouble. The Energy Saving Trust says many people have no issues after it is installed. When it does go wrong, these are the signs people report and that removal specialists look for:
- Damp patches on the inside of outside walls, often on the wall that faces the prevailing weather, and often worse after rain.
- Mould and black spotting on those walls, behind furniture and in corners.
- Cold spots where the fill has slumped or left gaps.
- Stained or crumbling plaster and peeling paint on external walls.
- Vermin nesting in the cavity, or scratching noises in the walls (Checkatrade).
- Bowing or cracking walls where an expanding foam has pushed the leaves apart, a case Ofgem's ECO4 guidance names directly.
None of these prove the insulation is to blame. CIGA asks homeowners to rule out the obvious first: blocked or leaking gutters, earth piled up against the walls, and condensation from drying washing or poor ventilation. A damp survey can tell the difference before you spend money on extraction.
Does cavity wall insulation cause dampness?
Not in a wall that was suitable and was filled properly. The Energy Saving Trust is clear: cavity wall insulation shouldn't cause damp if installed correctly. Damp after a fill usually comes from one of these:
- The wrong house. Walls exposed to driving rain or flooding, narrow cavities under 50mm, or brickwork and pointing in poor condition should not have been filled.
- A bridged cavity. Rubble or mortar in the cavity, or a fill that touches both leaves where rain soaks through, lets water track across to the inside.
- Poor maintenance after the install. Cracked render, failed pointing or overflowing gutters soak the outer leaf and the insulation with it.
- Flood damage. Saturated fill rarely dries out on its own.
Driving rain exposure zones
England's building regulations (Approved Document C) split the UK into four zones for exposure to driving rain, from sheltered (zone 1) to very severe (zone 4), using a national map. Approved Document C's table of maximum exposure zones is strict for bare brick: for injected fill (not UF foam) in a 50mm cavity behind fair-faced brick with tooled flush joints, the maximum recommended zone is 2, and with recessed mortar joints it is zone 1. A rendered or clad wall can take more exposure.
So a bare brick house in an exposed spot that was filled anyway is the classic case for extraction. Your surveyor should check your house against the exposure map and the state of the outer wall.
Can cavity wall insulation be removed?
Yes, and the process is non-destructive when a trained contractor does it. Checkatrade describes these steps:
- Survey. A specialist confirms the insulation type and condition.
- Drilling. Small holes (typically 22mm) are drilled through the outside mortar joints at regular intervals.
- Extraction. Industrial vacuum equipment pulls the fill out of the cavity.
- Making good. Holes are filled and repointed to match the existing mortar.
- Disposal. Mineral wool and polystyrene bead go to general waste; UF foam needs specialist disposal.
- Check. A follow-up inspection confirms the cavity is clear.
Can you remove cavity wall insulation yourself? No. It needs specialist extraction kit and training, and a half-cleared cavity can be worse than a full one. The Energy Saving Trust says to use a specialist cavity wall insulation removal company.
Cost of cavity wall insulation removal
| Item | Low | High | Average |
|---|---|---|---|
| Removal per m² | £21 | £22 | £21.50 |
| Removal, whole house | £1,680 | £2,520 | £2,100 |
| Extra for urea formaldehyde (UF) foam | Around £500–£1,000 more (specialist disposal) | ||
| Refilling afterwards (new cavity wall insulation) | Around £2,200 for a typical home in Great Britain (Energy Saving Trust, May 2026) | ||
Removal costs: Checkatrade, Cavity wall insulation removal cost, last updated July 2026 (ballpark averages; secondary source). Refill: Energy Saving Trust, updated 8 May 2026.
What changes the price: the size of the house, the type of fill, how wet and compacted it is, access (conservatories, extensions, three storeys), and whether you need a separate damp survey. Per-m² pricing helps if only one or two walls have failed. New insulation fitted by an installer carries 0% VAT until 31 March 2027; ask your contractor how VAT applies to the extraction itself.
The CIGA 25-year guarantee: how to claim
The Cavity Insulation Guarantee Agency (CIGA) provides independent 25-year guarantees for cavity wall insulation fitted by its registered installers. Many fills carry one. If your insulation is covered, check this before anything else, because CIGA says that where it finds a defect in the insulation or the way it was installed, remedial work is carried out free of charge under the terms of the guarantee.
| CIGA guarantee | What CIGA says |
|---|---|
| How long | Claims must be notified within 25 years of the installation date |
| Covers | Defects in materials or workmanship |
| Maximum rectification | Currently £20,000 |
| New owners | Stays valid for later owners and occupiers |
| Voided by | The insulation being altered or disturbed |
| Lost certificate? | You don't need it to raise a concern; a duplicate costs £60 including VAT |
Don't pull it out first. CIGA's terms say the guarantee is not valid if the insulation has been altered or disturbed. Paying a contractor to extract before CIGA has inspected could cost you a free fix.
Step by step
- Rule out maintenance problems such as blocked gutters or soil banked against the wall.
- Contact the installer named on your guarantee as soon as you can. CIGA says the installer will contact you within 24 hours to arrange an inspection.
- Go to CIGA if it isn't fixed. If the installer can't resolve it within 41 working days, or has gone out of business, contact CIGA: concerns@ciga.co.uk, 01525 853300, or its online concern form. You only need your address and postcode, plus two documents proving you own the home (one a current utility bill).
- Inspection. CIGA aims to acknowledge within 2 working days, arrange an inspection within 5 working days, and send a written report with its decision within 27 working days.
- Remedial work. If work is needed, CIGA aims to complete the whole process within 50 working days for simple cases and 90 for complex ones.
- Disagree? You can refer the dispute to independent arbitration.
Not sure if you have a CIGA guarantee? Email guarantees@ciga.co.uk. Not every fill is CIGA-backed: CIGA lists other providers, including the Enterprise ECO Guarantee (HIES), the IWA ECO Guarantee and Qualitymark Protection. CIGA no longer issues retrospective guarantees for fills done between 1995 and 1 January 2012 where the installer never registered one.
Is there a grant for cavity wall insulation removal?
Sometimes, and only in narrow cases. Here is the honest picture for 2026:
| Route | Will it pay for removal? |
|---|---|
| Your CIGA or other guarantee | Yes, if the defect is covered. This is the main route and it is free. ECO4 won't fund work a valid guarantee should cover. |
| ECO4 (to 31 December 2026) | Only as part of a funded project. Ofgem says extraction "is not an ECO measure", but its cost may be covered under a Building Fabric Repair increase, and new insulation to replace the faulty fill may then be funded. |
| Warm Homes: Local Grant (England) | Ask your council. Extraction isn't listed as a measure, but councils can spend part of their budget on ancillary works that support an install. |
| Building insurance | Check your policy. ECO4 rules require insurers to be checked first. |
| Warm Homes Loan | No. It doesn't fund insulation work. |
The ECO4 rules for funded extraction
Under Ofgem's ECO4 Delivery Guidance (version 4.0, 26 March 2026), extraction can only be covered when all of these apply:
- There is no valid guarantee that covers the work, the cost isn't covered by building insurance, and the original installer can't be contacted or refuses to fix it.
- The home is owner-occupied and starts in EPC band E, F or G. Building Fabric Repair increases are not available for private rented or social homes.
- A RICS chartered surveyor visits in person and recommends removal, with evidence that the insulation is directly causing the problem. Photos alone are not enough.
- The insulation has completely failed (not just a few gaps), for example where an expanding foam is damaging the structure, it is making damp worse, it is infested, it was ruined by flooding, or it failed because of historic poor maintenance that has since been put right.
The household must also qualify for ECO4 in the first place (usually through a means-tested benefit). The scheme caps the assumed repair spend at £1,500 per property in its scoring, and ECO4 ends on 31 December 2026, and suppliers can stop taking new homes before then. If you think you qualify, move now and see our cavity wall insulation grant guide for the current routes.
Checkatrade notes that some councils run funded removal programmes, so a call to your local authority is worth it. In Scotland, ask Home Energy Scotland; in Wales, ask Nest.
Government cavity wall insulation problems: if ECO or a grant paid for it
If your cavity was filled under the Energy Company Obligation (ECO) or another government scheme, the steps are similar but the people are different. Ofgem doesn't deal with ECO installation complaints directly, but it says who does:
- The installer first. Your paperwork should name it and the guarantee.
- TrustMark if the measure was installed after 1 January 2020: info@trustmark.org.uk.
- The guarantee provider (for insulation usually CIGA or the Installation Assurance Authority) if the installer has gone or won't help.
- The ombudsman: for CIGA and IAA, disputes go to the Centre for Effective Dispute Resolution (CEDR).
Had external or internal wall insulation fitted under ECO4 or GBIS instead? That's a separate government programme with free Find & Fix audits; see our external wall insulation cost guide for the details.
Watch out for claims companies. CIGA and Trading Standards warn homeowners to be careful with door-knockers and cold callers promising compensation for cavity wall insulation. Check the company, never sign on the doorstep, and report anything suspicious to Trading Standards through the Citizens Advice consumer helpline on 0808 223 1133 (England and Wales).
Who to contact
| Who | When | How |
|---|---|---|
| Your installer | First, as soon as you spot a problem | Details on your guarantee or paperwork |
| CIGA | Not fixed by the installer, or the installer has gone | concerns@ciga.co.uk · 01525 853300 |
| TrustMark | Grant or ECO measure installed after 1 Jan 2020 | info@trustmark.org.uk |
| Ofgem | To find out who installed or guaranteed an ECO measure | Ofgem ECO complaints process page |
| Trading Standards | Rogue traders or pushy claims companies | Citizens Advice consumer helpline 0808 223 1133 (England and Wales) |
| A RICS chartered surveyor | You need an independent report | rics.org |
Refill, leave it empty or insulate another way?
Once the cavity is clear and dried, a retrofit coordinator or surveyor decides what comes next. There are three options:
- Refill with a material suited to your exposure zone, once the cause (pointing, gutters, render) is fixed. Expect around £2,200 for a typical home on Energy Saving Trust figures.
- Leave it clear if the wall is too exposed or the cavity too narrow to fill safely.
- Insulate from outside instead. External wall insulation protects the outer wall from the weather and can suit exposed houses, but it costs far more: see the external wall insulation cost guide.
Planning a wider upgrade? The same survey visit can cover loft insulation, underfloor insulation and room-in-roof insulation. If your household is on a low income, the Warm Homes: Local Grant can fully fund insulation in England, and our free insulation grants page covers every route. For walls with no cavity at all, see the solid wall insulation grant.