Cavity wall insulation
What it is
If your home was built between 1920 and the early 1990s, the chances are it has a cavity wall — two skins of brick (or brick and block) with a gap between them. That gap is great for keeping moisture out, but it does nothing to keep heat in.
Cavity wall insulation fills the gap with insulating material — usually mineral wool, polystyrene beads, or a similar product — by drilling small holes in the mortar joints from outside, blowing the material in, and re-pointing the holes so they're nearly invisible when we're done.
It's a quick job. Most homes are completed in a single day. Done properly, it'll save you money for the next 30+ years.
Is it right for your home?
Does Your Home Need Cavity Wall Insulation?
Most homes between 1920 and the early 1990s have unfilled cavities. A few signs yours might be one of them:
Walls that feel cold to the touch in winter
Heating bills that feel higher than they should be
Rooms that take a long time to warm up
Condensation and damp on internal walls
A draught around skirting boards or near electrical sockets
The only way to know for sure is a survey. We use a borescope (a tiny camera) to look inside the cavity, check the wall construction, and see whether you've got insulation already (and if so, whether it's still doing its job — old insulation can slump, get damp, or fail entirely).
What You Get
What You'll Notice After Installation
Cavity wall insulation isn't dramatic the way external wall insulation is — there's no visible transformation, nothing to show off to the neighbours. But it does three things, reliably:
Lower Heating Bills
Typical savings are around £150–£250 a year for a semi-detached home, more for a detached. The insulation pays for itself in around 3–5 years and then keeps saving you money for the rest of its life.
A Warmer Home
The walls hold heat instead of letting it leak straight out. Rooms warm up faster, stay warm longer, and feel comfortable even when the heating's off.
Less Outside Noise
Mineral wool insulation is quietly brilliant at dampening sound. If you live near a busy road, you'll notice the difference within a week.
How it works
The Installation
Cavity wall installation is one of the cleanest, fastest insulation jobs there is.
Free Survey
We come out, check the cavity with a borescope, confirm the wall construction, and check there's nothing that would stop us doing the job (timber-frame walls, narrow cavities, existing damp, or unsuitable construction). No charge, no pressure.
Written Quote
A clear, fixed-price quote in writing within a few days. Materials, installation, making good — all included.
Installation Day
We turn up, drill 22mm holes in the mortar joints (not the bricks), inject the insulation material, and re-point the holes with matching mortar. Most homes are done in 4–6 hours. You don't need to leave.
25-Year Guarantee
You get a CIGA (Cavity Insulation Guarantee Agency) certificate covering the work for 25 years. If anything ever goes wrong, you're protected — and we're at the end of the phone if you need us.
Why Rockwarm
Why Choose Rockwarm for Cavity Wall Insulation?
Cavity wall insulation has had a bad reputation in some areas, and not without reason.
There have been a lot of poor installations over the years — wrong material for the wall, badly drilled, gaps left in the cavity, damp problems caused by careless work. We've seen plenty of failed jobs from other companies that we've come in to fix.
40 years installing insulation
Sucessfully traded in the UK insulation industry for 40 years, with a team of experienced, qualified installers and a reputation for quality.
Proper survey first
We use a borescope every time. If your wall isn't suitable, we'll tell you — we don't force jobs that shouldn't happen.
Our own installers
Same trained team, every job. No subcontractors.
25-year CIGA guarantee
A 25-year guarantee backed by the Cavity Insulation Guarantee Agency (CIGA).
TrustMark certified.
Government-endorsed quality standard.
Right material for your wall
Mineral wool, EPS bead, or polyurethane foam — we use what's right for your specific cavity, not what we've got most of in the van.
Highly recommended
We have excellent reviews, with a reputation for professionalism, quality, and customer service.
Areas we cover
Cavity Wall Insulation Across the Midlands
Based in Nuneaton, Rockwarm surveys and installs cavity wall insulation for suitable homes across Coventry, Birmingham, Warwickshire, Leicestershire, and the wider Midlands.
Coventry and Warwickshire
Coventry, Rugby, Warwick, Leamington Spa, Kenilworth, and nearby towns
Nuneaton and North Warwickshire
Nuneaton, Bedworth, Atherstone, Hinckley, and surrounding villages
Birmingham and Solihull
Birmingham, Solihull, Sutton Coldfield, and wider West Midlands homes
Leicestershire and nearby Midlands areas
Lutterworth, Market Bosworth, Leicester outskirts, and neighbouring postcodes
Not sure whether we cover your postcode, or whether your walls are suitable? Check our Midlands coverage or book a free survey and we will give you a clear answer.
Local advice
Choosing the Right Wall Insulation Route
Cavity wall insulation is a strong, low-disruption option for many Midlands homes, but it is not right for every property. Rockwarm starts with a survey so you can compare the practical route before committing to work.
Check Midlands coverage
See how Rockwarm covers Coventry, Nuneaton, Birmingham, Warwickshire, Leicestershire, and nearby areas.
Learn moreCompare external wall insulation
Useful if your home has solid walls, a narrow cavity, failed insulation, or an unsuitable exposed elevation.
Learn moreCompare deeper retrofit costs
Use the cost hub if you are weighing cavity insulation against a larger external wall insulation project.
Learn moreLook at loft insulation too
A helpful next step if you want to reduce heat loss across the whole property, not just the external walls.
Learn moreProof and research
Make the decision with evidence, not guesswork.
If you are comparing cavity wall insulation contractors in the Midlands, combine survey advice with independent reviews, real project examples, and practical guidance on where cavity insulation fits against other retrofit options.
FAQs
Cavity Wall Insulation Questions
Cavity Wall Insulation
Ready for a Warmer Home and Lower Bills?
Book your free survey. No obligation, no pressure — just an honest assessment of whether cavity wall insulation is right for your home, and a fixed-price quote if it is.
