Cavity Wall Insulation Installation & Re-Insulation
Cavity wall insulation done properly makes a home warmer, cheaper to heat and better rated on its EPC. Proofterior install cavity wall insulation — and re-insulate after extraction — only after a survey confirms your walls are suitable, using bonded polystyrene beads that will not wick rain across the cavity. Available across Dorset, Hampshire and Wiltshire and 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
What is Cavity Wall Insulation Installation & Re-Insulation?
Cavity wall insulation installation means injecting an insulating material into the gap between the two leaves of a wall through small holes drilled at the mortar joints. The common materials are mineral wool, expanded polystyrene (EPS) beads and polyurethane foam. Bonded EPS beads are coated with an adhesive as they go in, so they lock together, fill the cavity evenly and do not slump. Because the beads are water-resistant and leave tiny drainage paths, they are less likely to carry rain across the cavity than loose fibre — which is why we use them for re-insulation after removal and in more exposed walls where filling is still appropriate. The single most important step is the pre-installation survey: we check cavity width, the condition of the outer leaf, pointing and render, gutters, existing damp and the exposure of each wall. If a wall is not suitable, we will say so and suggest alternatives such as internal wall insulation.
The warning signs to look for
Catching the problem early keeps repairs simpler and less costly. If you notice any of these signs, it is worth booking a specialist survey before the damage spreads.
Book a complimentary survey
- Your cavity is empty and the home loses heat quickly
- Failed insulation has just been extracted and the cavity is clean and dry
- You want to improve your EPC rating before selling or letting
- Cold external walls and high heating bills
- Parts of the cavity were missed when it was first filled
- An extension was built with an unfilled cavity
- Your home is in good repair with sound pointing and gutters
- You want insulation that suits South Coast weather
Our treatment process
Every job follows the same careful, diagnosis-first method — so you know exactly what is happening and why at each stage.
Suitability survey: borescope check of cavity width and condition, plus pointing, render, gutters, damp and exposure.
Repairs first: any defects that could let water reach the insulation are put right before anything is injected.
Preparation: air bricks, flues and vents are sleeved or protected so ventilation is never blocked.
Drilling: holes are drilled at the mortar joints in a set pattern across each wall.
Injection: bonded polystyrene beads are blown in and lock together to fill the cavity evenly, top to bottom.
Finish: holes are made good with matching mortar, the fill is checked and your guarantee paperwork is issued.
Mineral wool, beads or foam?
All three insulate well when they stay dry and fill the cavity evenly. The difference is how they behave when the outer wall gets wet, and whether they can be removed later if something goes wrong.
For most South Coast homes, and for every re-insulation after extraction, bonded polystyrene beads are our recommendation.
- Mineral wool — lowest cost, but can wick water and slump in exposed walls.
- Bonded EPS beads — lock together, resist water and do not settle; can be extracted if ever needed.
- Polyurethane foam — high performance and adds rigidity, but very hard to remove and not suited to damp walls.
Cavity Wall Insulation Installation & Re-Insulation — from our recent projects
Real photos from Proofterior jobs across Dorset, Hampshire and Wiltshire — carried out by our own in-house team.
Included as standard
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.
Cavity Wall Insulation Installation & Re-Insulation across Bournemouth, Poole & the South Coast
Along the coast from Weymouth to Southsea, exposure to wind-driven rain is the deciding factor in whether a cavity should be filled and with what. That is why we survey every wall before quoting cavity wall insulation in Bournemouth, Poole or Christchurch, and why we favour bonded beads for re-insulation. Inland in Salisbury, Andover, Winchester and Romsey, more walls are sheltered enough for a straightforward fill. Our team works across Bournemouth, Poole, Christchurch, Southampton, Portsmouth, Winchester, Salisbury and the towns and villages in between.
Covering Dorset, Hampshire & Wiltshire
Local knowledge, specialist expertise and lasting protection for the home you care about.
Everything you might be wondering
It depends on the wall. Mineral wool is cheaper but can wick moisture in exposed walls. Bonded polystyrene beads fill evenly, do not slump and resist water, so they suit re-insulation and South Coast exposure well. Foam has high performance but is very hard to remove later. We recommend the right material after the survey.
Generally, yes if it has an unfilled cavity of at least 50mm, the brickwork, pointing and render are in good repair, the walls are not already damp and the wall is not severely exposed to driving rain. Non-traditional, timber-framed and steel-framed homes usually are not suitable. Our survey confirms it wall by wall.
Most homes are done in a few hours to a day. Repairs needed beforehand, such as repointing, are scheduled first.
Filling an empty cavity is one of the measures that usually improves an EPC rating, because it cuts heat loss through the walls. The exact improvement depends on the property.
Yes. Once the cause of the damp is fixed and the cavity is clean and dry, we re-insulate with bonded beads where the wall is suitable.
No. Air bricks, vents and flues are sleeved or protected before injection so subfloor and appliance ventilation keeps working.
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.