Cavity wall insulation in the UK: compare quotes & installers
Save heat, cut bills and improve comfort. Compare whole-of-market cavity wall insulation options with EnergyPlus.co.uk—get matched with suitable installers and quotes for your home.
- See whether your property type is likely to be suitable
- Compare installers and quotes (whole-of-market comparison)
- Check potential savings and grants support where available
- Get help understanding the risks (damp, ventilation, workmanship)
For UK homes only. Estimates vary by property. We’ll ask a few questions to help you compare suitable options.
Get cavity wall insulation quotes for your home
Cavity wall insulation can be one of the quickest ways to reduce heat loss—if your walls and exposure are suitable. EnergyPlus.co.uk helps you compare whole-of-market options by matching you with installers based on your property details.
Use the form to request quotes. You’ll get a clearer view of:
- Likely insulation type for your home (e.g. bead, mineral fibre, foam where appropriate)
- Typical price range and what’s included (survey, install, ventilation checks)
- Potential savings and payback expectations
- Any available support (e.g. ECO4 eligibility checks)
Important: Cavity wall insulation isn’t right for every home. A proper survey should check wall condition, exposure, damp risk and ventilation before installation.
Tip: If you’ve had damp, mould, or wind-driven rain issues, mention it when you’re contacted. A good installer will check exposure and wall condition before recommending insulation.
What is cavity wall insulation?
Many UK homes (particularly those built from the 1920s onwards) have cavity walls: two layers of masonry with a gap (the cavity) between them. If that cavity is uninsulated, warm air inside your home can escape through the walls, making rooms feel colder and increasing heating demand.
Cavity wall insulation fills that gap with an insulating material to reduce heat transfer. Installation is typically done from the outside by drilling small holes in the mortar lines, injecting the insulation, then making good the holes.
Common materials (UK)
- EPS beads (polystyrene beads) – often used; can be bonded to reduce settlement.
- Mineral wool fibre – widely used; needs correct installation for consistent fill.
- Foam – used in some situations; suitability depends on wall type, ventilation and exposure.
How long does it take?
For a typical house, cavity wall insulation can often be completed in a few hours. A survey should happen first to confirm the cavity is suitable and to check for damp risk, wall condition and ventilation requirements.
Benefits of cavity wall insulation
When your home is suitable and installation is done well, cavity wall insulation can improve comfort quickly and help you get more from your heating system.
Lower heat loss through walls
Walls can be a major source of heat loss in uninsulated homes. Filling the cavity helps keep warm air in for longer.
Better comfort and fewer cold spots
Rooms often feel less draughty and more even in temperature, particularly in bedrooms and living rooms on external walls.
Potential bill savings
Savings depend on your home, heating use and energy prices, but insulation typically reduces the amount of heating required.
Supports other upgrades
Insulation can improve the effectiveness of a heat pump, boiler controls, and draught-proofing by reducing overall heat demand.
May improve EPC rating
Adding insulation can help your home’s EPC assessment by reducing calculated heat loss—useful for future resale or renting requirements.
Can be eligible for support
Some households may qualify for energy-efficiency schemes (such as ECO4). Eligibility depends on circumstances and property factors.
Next step: check whether your home is likely to be suitable before you book anything in.
Is my home suitable for cavity wall insulation?
Suitability is about more than whether your home has a cavity. A competent survey should check the wall construction, condition and local exposure to wind-driven rain.
Often suitable
- Homes built roughly 1920s–2000s with unfilled cavities
- Brick or block outer walls in good condition
- Standard cavity widths (varies by era)
- No ongoing damp problems and good ventilation
May need extra checks (or not suitable)
- Exposed locations (coastal or high rainfall / wind-driven rain areas)
- Older solid walls (common pre-1920) — these typically need internal or external wall insulation instead
- Walls with cracks, failing pointing or poor render
- Existing damp, mould, or bridged cavities
- Non-standard construction (timber frame, rubble stone) — needs specialist advice
Quick check: Look at the brick pattern. If you can see alternating brick ends (header courses) and your home is older, it may be solid wall rather than cavity. Not sure? Request quotes and ask for a survey—don’t assume.
Cavity wall insulation costs and savings (UK)
Prices vary depending on wall area, access, property shape, insulation material, and any prep work (like making good pointing or addressing vents). Use the table below as a guide, then request tailored quotes.
| Home type (typical) | Typical supply & install range | What affects cost most | Savings potential |
|---|---|---|---|
| Mid-terrace | Often £600–£1,200 | Wall area, access, number of storeys | Moderate (depends on heating use) |
| Semi-detached | Often £800–£1,500 | Gable wall size, scaffolding needs | Moderate to higher |
| Detached | Often £1,200–£2,500+ | Total wall area, access, complex shapes | Higher (more exposed wall area) |
| Bungalow | Often £900–£2,000 | Wall area, cavity width, finish type | Moderate to higher |
What’s usually included
- Pre-install survey and suitability checks
- Drilling and injection / fill process
- Making good of drill holes
- Workmanship warranty (length varies)
Questions to ask about price
- Is scaffolding required and included?
- Is ventilation assessed (e.g. extractor fans, air bricks, trickle vents)?
- How will the installer manage damp risk and exposure?
- What warranty paperwork will I receive?
To compare like-for-like, aim to get at least 2–3 quotes and make sure each quote states the material type and the survey outcome.
How cavity wall insulation is installed
Installation should be quick, tidy, and driven by the survey findings. Here’s what a good process often looks like.
- Survey and checks: the installer assesses wall type, cavity width, exposure, existing damp issues, ventilation, and any blockages in the cavity.
- Prep work: addressing issues such as damaged pointing/render, clearing vents, and confirming access (ladders/scaffold).
- Drilling pattern: small holes are drilled in mortar joints to reach the cavity at set intervals.
- Injection/fill: insulation is installed to fill the cavity evenly (method depends on material).
- Making good: holes are filled to match mortar as closely as possible; the area is cleaned down.
- Aftercare and paperwork: you receive warranty/guarantee info and any advice on ventilation and moisture management.
How to prepare: Clear access to external walls, let the installer know about any previous damp treatments, and check if air bricks or vents must remain unobstructed.
Risks, damp concerns and how to avoid problems
Most issues linked to cavity wall insulation come down to poor suitability checks or poor workmanship. These are the key risks to understand before you proceed.
| Risk | What it can look like | How to reduce the risk |
|---|---|---|
| Damp/condensation issues | Musty smell, mould growth, wet patches on internal walls | Insist on a proper survey. Address existing damp first. Check ventilation (extractors, trickle vents, air bricks). |
| Water penetration in exposed areas | Damp after wind-driven rain, especially on gable ends | Confirm exposure assessment. Repair pointing/render. Consider alternatives if exposure is high. |
| Incomplete fill or settlement | Cold patches remain; performance lower than expected | Choose an experienced installer; ask what quality checks they use and what warranty is provided. |
| Blocked vents/airflow issues | Condensation increases; stuffy rooms | Ensure vents remain clear and fit appropriate ventilation where needed; get advice for kitchens/bathrooms. |
Red flag: Anyone willing to install without checking exposure, wall condition and ventilation is not someone you want working on your home.
Grants and support (ECO4 and other schemes)
Some UK households may be able to get cavity wall insulation part-funded or fully funded through government-backed or supplier-led schemes (commonly referenced under ECO4). Eligibility can depend on household circumstances, benefits, income, EPC band, and the property’s suitability for the measure.
What you can do now
- Find your latest EPC (or plan to get one if needed)
- Be ready to share basic household details during the quote process
- Ask what documentation is required before work starts
Not eligible? You can still compare
Even without grant support, comparing multiple quotes can help you find the right balance of price, approach, materials, and confidence in the survey.
If you want to explore support routes, start here: request cavity wall quotes and ask about grant eligibility during the follow-up.
Cavity wall insulation FAQs
How do I know if I have cavity walls?
Many homes built from the 1920s onwards have cavity walls, but not always. A survey is the reliable way to confirm. Brick pattern and wall thickness can offer clues, but they’re not definitive.
Will it make my home damp?
If a home is unsuitable (for example, high exposure or existing damp) or installation is poor, problems can occur. A good survey, correct material choice and proper ventilation checks reduce risk significantly.
How much disruption is there?
Usually minimal. Most work is external, and the job can often be completed within a day. There may be drilling noise, and you may need access to a power supply.
Can flats get cavity wall insulation?
Sometimes, but it depends on the building construction and who controls the external walls. If you’re a leaseholder, you may need freeholder or managing agent approval.
Is it worth doing if I plan to get a heat pump?
Often yes (if suitable). Reducing heat demand can improve comfort and make a heat pump system easier to size and run efficiently.
What else should I do alongside cavity wall insulation?
Loft insulation, draught-proofing, heating controls and ventilation improvements commonly complement cavity wall insulation. The best package depends on your home and budget.
Have a specific question about your property? Request quotes and raise it during the survey stage.
Why homeowners use EnergyPlus.co.uk
Choosing insulation is as much about confidence as it is about cost. Our comparison-first approach helps you understand your options before you commit.
Whole-of-market comparison
We aim to match you with suitable installers so you can compare approaches, materials and pricing—not just one quote.
Property-led guidance
We highlight the factors that matter in the UK (exposure, damp risk, ventilation) so you can ask better questions.
Clear next steps
From suitability checks to survey expectations, you’ll know what should happen and what paperwork to keep.
Homeowner feedback (examples)
“The survey explained why our gable wall needed extra checks. We compared two quotes and chose the installer who talked through ventilation.”
“Easy to compare prices and what’s included.” The second quote included making good and a longer warranty.”
Trust checks to look for
- Written survey outcome (not just a quick visual)
- Clear statement of insulation material and method
- Workmanship warranty details in writing
- Aftercare contact details
Ready to compare cavity wall insulation quotes?
Start with a quick form fill. We’ll use your property details to help match you with suitable installers and quote options across the market.
No obligation. Survey and suitability checks should be completed before any installation is agreed.
What you’ll need
- Your postcode
- Property type and approximate age
- Your preferred contact details
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