Cavity Wall Insulation Specialists in Dorset, Hampshire & Wiltshire
Cavity wall insulation should make your home warmer — but when it is the wrong material, badly installed or fitted in an exposed wall, it can pull rain across the cavity and cause damp, mould and cold spots. Proofterior survey, diagnose and put it right across Dorset, Hampshire and Wiltshire: borescope inspections, full cavity wall insulation removal, cavity clearance and re-insulation with the right material, all backed by our 25-year insured guarantee.
- ISSE accredited
- 25-year insured guarantee
- In-house specialist team
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Tell us what is happening and a specialist will find the real cause and give you a fixed price to fix it. No obligation.
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Genuine reviews from local homeowners
Over 200 verified reviews across Checkatrade, Google and Yell
“Excellent service from start to finish. The survey was thorough and professional, with honest, evidence-based advice rather than trying to sell unnecessary work. I came away with complete peace of mind.”
Alex Richards-Taylor
Google review
“Excellent service throughout. Ashton came out to look at an issue raised on a part-exchange survey and, rather than recommend expensive remediation, told me honestly there was nothing wrong with the wall. Great to have an honest discussion.”
Ian M.
BH16 · Damp Investigation
“Dylan and the Proofterior team were amazing. The report was incredibly comprehensive. Can’t recommend them enough.”
Sam Short
Google review
“Very pleased with the work on our living room and bedroom walls. Punctual, polite and friendly, and completed on time even though it was Easter week. Many thanks to everyone at Proofterior.”
Chris G.
BH20 · Penetrating Damp Treatment
“Dan was very thorough, professional and polite. Quick to respond and I would highly recommend.”
Malik R.
Yell · Quick & Professional
“The workmen were clean, pleasant and efficient and took just one day. The very next day we noticed a big difference with the damp issue. Many thanks.”
Nick Bennett
Google review
“Able to fit my job in for the next day and completed in a day as agreed. Not the lowest quote, but it comes with a 25-year guarantee, which I wanted — long-term peace of mind was vital.”
Alan M.
BH23 · Flat Roof Reseal
“Ashton was so friendly and informative. I’ve gone from worried to empowered — someone you can trust to do the right thing.”
Suzanna Furbank
Google review
“Really amazing service. Dan provided a really thorough damp investigation and a very helpful damp report. Very quick responses too.”
Paul A.
Yell · Damp Investigation
“Happy with the speed — a full flat survey within a week. They explained our options, the price was extremely competitive, and our tenants are pleased with their fresher, safer flat.”
Verified Customer
SP6 · Damp Proofer
“Dan provided a very professional service from start to finish. Very good communication and a first-class job.”
Mark H.
Yell · Professional Service
“Excellent service from start to finish. The survey was thorough and professional, with honest, evidence-based advice rather than trying to sell unnecessary work. I came away with complete peace of mind.”
Alex Richards-Taylor
Google review
“Excellent service throughout. Ashton came out to look at an issue raised on a part-exchange survey and, rather than recommend expensive remediation, told me honestly there was nothing wrong with the wall. Great to have an honest discussion.”
Ian M.
BH16 · Damp Investigation
“Dylan and the Proofterior team were amazing. The report was incredibly comprehensive. Can’t recommend them enough.”
Sam Short
Google review
“Very pleased with the work on our living room and bedroom walls. Punctual, polite and friendly, and completed on time even though it was Easter week. Many thanks to everyone at Proofterior.”
Chris G.
BH20 · Penetrating Damp Treatment
“Dan was very thorough, professional and polite. Quick to respond and I would highly recommend.”
Malik R.
Yell · Quick & Professional
“The workmen were clean, pleasant and efficient and took just one day. The very next day we noticed a big difference with the damp issue. Many thanks.”
Nick Bennett
Google review
“Able to fit my job in for the next day and completed in a day as agreed. Not the lowest quote, but it comes with a 25-year guarantee, which I wanted — long-term peace of mind was vital.”
Alan M.
BH23 · Flat Roof Reseal
“Ashton was so friendly and informative. I’ve gone from worried to empowered — someone you can trust to do the right thing.”
Suzanna Furbank
Google review
“Really amazing service. Dan provided a really thorough damp investigation and a very helpful damp report. Very quick responses too.”
Paul A.
Yell · Damp Investigation
“Happy with the speed — a full flat survey within a week. They explained our options, the price was extremely competitive, and our tenants are pleased with their fresher, safer flat.”
Verified Customer
SP6 · Damp Proofer
“Dan provided a very professional service from start to finish. Very good communication and a first-class job.”
Mark H.
Yell · Professional Service
When cavity wall insulation helps — and when it causes damp
Most homes built from the 1920s onwards have two leaves of masonry with a gap between them. That cavity was designed to stop rain soaking through to the inside: water that gets through the outer brick runs down the inside face of it and drains away at the bottom. Filling it with insulation cuts heat loss, but it also removes that air gap.
In a sheltered, well-maintained wall with the right fill, that works well. In an exposed wall facing wind-driven rain — common along the South Coast — or where pointing, render or gutters are failing, wet insulation can carry moisture straight across to the inner wall. Slumped or patchy fill leaves cold spots where condensation and black mould form.
Our ISSE accredited surveyors find out which situation you are in. We look inside the cavity with a borescope, take moisture readings and check the outside of the building, then give you an honest written report — whether that means leaving good insulation alone, fixing the external defect, or removing failed cavity wall insulation and re-insulating properly.
Common cavity wall insulation problems
Failed cavity wall insulation usually comes down to one of four causes. The right fix depends on which one you have.
Wet insulation & penetrating damp
In exposed walls, wind-driven rain soaks the outer leaf and wicks across mineral wool or loose fibre to the inner wall, causing damp patches, stained plaster and peeling paint.
Slumped or patchy fill
Fibre fill that has settled or was never fully injected leaves voids. These become cold spots where condensation and black mould form, usually in corners and below windows.
Unsuitable walls
Narrow cavities, rubble-filled cavities, non-traditional construction and walls that were already damp should not have been filled at all. The insulation turns an old problem into a worse one.
Bridging & building defects
Mortar droppings, debris or failed pointing, render and gutters let water reach the fill. Left alone, this can corrode wall ties and rot joist ends built into the wall.
Real damp projects across the South
Genuine Proofterior projects across Dorset, Hampshire and Wiltshire — including cavity clearance and bridging problems behind internal damp.
Signs your cavity wall insulation has failed
If any of these appeared after cavity wall insulation was installed, a cavity wall survey will confirm whether the insulation is to blame.
Book a complimentary survey- Damp patches on external walls that appeared after insulation was fitted
- Black mould in corners, behind furniture or around windows
- Damp or staining that gets worse after wind-driven rain
- Cold spots on walls, picked up by touch or a thermal camera
- Peeling wallpaper, blown plaster or salt marks on inner walls
- Higher heating bills despite the insulation
- Rust staining or horizontal cracks in mortar beds (wall tie corrosion)
- Rotting skirting boards or floor joist ends on outside walls
Our cavity wall insulation services
Our work across Dorset, Hampshire & Wiltshire
Real photos from recent Proofterior projects — every job surveyed, treated and finished by our own in-house team.
From first call to lasting protection
Complimentary survey
Complimentary survey with borescope inspection and moisture readings.
Expert diagnosis
A clear written report: what is in the cavity, why it is failing and what it needs.
Specialist treatment
Our vetted, Proofterior-trained team removes, repairs or re-insulates as agreed.
25-year guarantee
A camera check, making good, and your 25-year insured guarantee.
How we put it right
Every job starts with evidence, not assumptions. Once we know why the insulation is failing, we fix the cause and the damage.
Borescope cavity survey
Small holes in the mortar joints let us film inside the cavity, see the condition and type of fill, and spot debris, voids or corroded wall ties.
Cavity wall insulation extraction
Failed fill is broken up with compressed air and removed with an industrial vacuum, then the cavity is checked on camera and the holes made good to match.
External repairs
We repair the pointing, render, gutters and downpipes that let water in, and can apply a breathable masonry water-repellent cream to exposed walls.
Re-insulation & internal repair
Where the wall is suitable we re-insulate with bonded beads, then treat any mould and re-plaster damp-damaged walls.
Built to impress, built to last
Diagnosis first
We identify the real cause before recommending any treatment. No guesswork, and never unnecessary work.
In-house specialist team
Vetted, Proofterior-trained specialists, managed by us from survey to completion. No compromises.
25-year guarantee
Every treatment is backed by our 25-year insured guarantee, giving you lasting protection and peace of mind.
Covering Dorset, Hampshire & Wiltshire
Local knowledge, specialist expertise and lasting protection for the home you care about.
Everything you might be wondering
It can. Correctly installed in a suitable, sheltered wall, cavity wall insulation should not cause damp. But in walls exposed to wind-driven rain, walls with defects such as failed pointing or leaking gutters, or where the wrong material was used or the fill has slumped, it can carry moisture across the cavity or create cold spots where condensation and mould form.
Damp or mould on external walls that started after the insulation went in is a strong clue, but other causes such as condensation, leaks or rising damp look similar. A borescope survey shows what is actually in the cavity and whether it is wet, slumped or bridged, so you only pay to fix the real cause.
Yes. Mineral wool, loose fibre and most bead systems can be extracted through holes drilled in the mortar joints using compressed air and an industrial vacuum. Foam insulation is far harder to remove and sometimes means taking out sections of brickwork. Our survey confirms what you have.
Often, yes — an empty cavity loses heat. Once the cause of the damp is fixed and the cavity is clean and dry, we can re-insulate with bonded polystyrene beads where the wall is suitable. In very exposed walls we may recommend leaving the cavity clear and improving insulation another way.
Not before your claim is settled. Contact your original installer first and, if they do not resolve it, escalate to CIGA. Removing the insulation privately during a claim can affect the guarantee. We can provide independent survey evidence to support your claim.
Yes. We carry out cavity wall surveys, removals and re-insulation across Dorset, Hampshire and Wiltshire, including Bournemouth, Poole, Christchurch, Southampton, Portsmouth, Winchester and Salisbury.
Get clear, honest answers about your home
A qualified specialist will visit your property, carry out a thorough inspection and give you clear recommendations in plain English — everything explained in one visit, with no obligation.