01 The Problem

Your Walls Are Damp Because the Insulation Has Failed

Cavity wall insulation installed years ago can fail in several ways. The product degrades, it was installed incorrectly, or water ingress has saturated it over time.

When cavity wall insulation fails, it does not simply stop working. Wet insulation bridges the air gap inside the cavity and draws moisture from the external masonry directly to the internal wall face. The result is persistent damp that cannot be fixed with anti-mould paint, re-plastering or improved ventilation, because the source is inside the wall structure itself.

The only permanent fix is to remove the failed material. That requires specialist extraction equipment, a trained team, and a proper survey first.

Damp returns after treatment

You have replastered, painted with anti-mould products, or improved ventilation, but the damp keeps coming back in the same spots.

Mould comes back every time

Mould that returns within weeks of treatment almost always has a structural moisture source behind it, not a surface condensation problem.

Cold walls despite insulation

Internal walls that feel cold to the touch even though the cavity was filled decades ago, suggesting the insulation has compacted, saturated or been displaced.

Cavity wall extraction equipment in use on a South Wales property, specialist removal of failed insulation

02 The Solution

Specialist Extraction. Proper Survey First. No Guesswork.

1 Day

Most extractions completed within a single working day

We begin with a borescope survey: a small camera is inserted through a drilled hole in the external masonry to visually confirm the condition and material type of the existing cavity fill. You receive a written report before any extraction work is agreed. If extraction is not needed, we tell you that too.

Borescope assessment

A small camera is inserted through a drilled hole to visually confirm the condition and material type in the cavity. You receive a written report and recommendation before any extraction is agreed.

Extraction, any material type

High-powered vacuum extraction equipment removes the failed fill through small-diameter holes drilled at regular intervals in the external masonry. We extract Mineral Wool (MW), Expanded Polystyrene beads (EPS / Airpop), Urea Formaldehyde foam (UF), Polyisocyanurate (PIR), Polyurethane (PUR) and Phenolic (PF). All extracted material is collected and disposed of correctly.

Re-pointing

All drilled holes are filled and re-pointed with matching mortar. The external finish is restored as closely as possible to the original masonry.

Post-extraction inspection and options

The cavity is inspected to confirm it is clear. A drying-out period of several weeks is recommended before any decision on re-insulation. Re-insulation with a suitable modern product is quoted separately if appropriate.

03 Why Extract

What Changes After Extraction

Removing failed insulation does not just stop the damp. It removes the structural moisture bridge that was causing it.

Persistent damp resolved at the source

Wet insulation in the cavity is the cause of the moisture bridge, not a symptom of something else. Removing it eliminates the source permanently, not just the visible effect.

Stops mould returning for good

Mould that keeps coming back despite surface treatment almost always has a structural moisture source driving it. Extraction removes that source, so treated surfaces stay clean.

Protects the wall structure long-term

Wet insulation left in place long-term accelerates deterioration of the masonry, internal plaster and wall ties. Extraction removes the cause of that progressive damage.

Opens the door to modern re-insulation

Once the failed material is out and the cavity has dried, modern cavity wall insulation can be installed correctly and confidently. Re-insulation is quoted separately once the extraction is complete.

Professional assessment before any work starts

Every extraction starts with a borescope survey. You will not be sold an extraction if the insulation is in good condition or if a different cause is identified during the survey.

04 Honest Guidance

Is Cavity Wall Extraction Right for You?

Extraction is the right answer in some cases, not all. We would rather give you an honest answer than charge for a service you do not need.

Extraction is likely a good fit if:

You have persistent damp patches on internal walls that have not responded to anti-mould paint, replastering or improved ventilation.
Mould keeps returning in the same areas after being treated.
A surveyor or damp specialist has identified failed cavity wall insulation as the underlying cause.
You know the cavity was filled and the material has aged significantly, been saturated, or was installed in an era known for problematic products such as urea formaldehyde foam.
An insulation installer has told you extraction is needed before new cavity wall insulation can be fitted.

Extraction may not be the answer if:

The cavity has not been inspected and you are not certain it is filled. Start with an assessment to confirm what is there before assuming extraction is needed.
You have a solid-walled property with no cavity. Extraction is not applicable to solid walls. If you are looking for insulation options for solid walls, see our internal wall insulation page.
You have damp but the cause has not been identified as cavity insulation. A damp survey should identify the actual cause before any remediation work is carried out.

05 Customer Reviews

What Customers Say

4.4

Google Reviews, First Choice Energy Ltd

View All Google Reviews

Luke Jenkins

Swansea, South Wales

Absolutely first class from start to finish. Turned up when they said they would, explained everything clearly and left the site spotless. Could not fault the service at all.

First Choice Energy

Dan Evz

Cardiff

Professional, knowledgeable and honest. They did not try to oversell anything, just explained what was needed and got on with the job. Really impressed with the standard of work.

First Choice Energy

Sarah B.

Bristol

From the initial survey to completion, the whole team were excellent. Everything was explained at every stage and they were tidy throughout. Very happy with the result.

First Choice Energy

06 How It Works

From First Call to Clear Cavity

Every extraction job starts with an honest assessment. No extraction is agreed before the survey confirms it is needed.

Enquiry

Call us or fill in the form. Tell us about the damp problem, what has been tried, and roughly when the cavity was filled. We will arrange a convenient date for the assessment.

Day 1

Borescope Assessment

Our surveyor drills a small hole, inserts a borescope camera and inspects the cavity. You receive a written report confirming the condition of the insulation and whether extraction is recommended.

Within 1, 2 weeks

Written Quotation

Based on the survey findings, you receive a clear written quote for the extraction. No hidden charges. If the assessment finds the insulation is sound and extraction is not warranted, we tell you that plainly.

Within days of survey

Extraction Carried Out

Holes are drilled at regular intervals in the external masonry. The specialist vacuum extraction system removes the failed material in sequence. All holes are re-pointed with matching mortar on the same day.

Usually 1 day

Post-Extraction Report

We confirm the cavity is clear and advise on the drying-out period before any re-insulation can take place. If re-insulation is appropriate, a separate quote will follow once the cavity has dried.

Same day

Drying Period and Re-Insulation Options

The cavity is left empty to dry for several weeks. Once dry, modern cavity wall insulation can be installed with confidence. Re-insulation is a separate service, quoted on its own merits.

Several weeks later

07 Why First Choice Energy

Specialists, Not Generalists

Cavity wall extraction requires the right equipment, the right skills, and the right approach. It cannot be done by a general builder. Here is why customers across South Wales and South West England choose us.

PAS2030 and TrustMark Certified

We hold PAS2030 certification and TrustMark accreditation, meeting the quality standards required for retrofit insulation work. Every job is carried out to the same standard, every time.

Survey before extraction. Always.

We do not start work until we have visually confirmed the condition of the insulation with a borescope survey. You receive a written report. No extraction is carried out without your agreement based on actual evidence.

NEBOSH Qualified Director

Aaron Davies, our director, holds a NEBOSH qualification in Health and Safety Management for Construction. No local competitor leads with this. Every site we work on is managed to the same standard.

South Wales Roots. South West Reach.

We are based in Llanelli, Carmarthenshire, and work across South Wales, South West England and West England. Local team, local knowledge, fast response.

08 Case Study

Damp Treated Twice. Still Coming Back. Fixed.

Swansea, South Wales

3-Bed Semi, Persistent Damp on Internal Walls Despite Two Previous Treatments

The homeowner had been dealing with damp patches in two downstairs rooms for several years. Anti-mould paint had been applied twice and the rooms had been replastered once. The damp returned within a few months each time. A damp specialist eventually identified the likely cause as failed cavity wall insulation, which had been installed in the 1980s.

Our surveyor confirmed the diagnosis with a borescope inspection: the original mineral wool insulation had become heavily saturated across most of the rear elevation. Extraction was carried out over a single day. The cavity was left to dry for six weeks. The homeowner confirmed that by the following autumn, the damp had fully resolved.

~£750

Extraction cost

1 Day

Extraction completed

Resolved

Damp, following autumn

Cavity wall extraction case study — scaffolding and equipment in place at a South Wales property

09 Accreditations

Certified to the Standards That Matter

Cavity wall extraction is specialist work. These accreditations confirm we hold the certifications required to carry it out correctly.

PAS2030 Certified

The quality standard required for retrofit insulation measures. Issued by Blueflame. Confirms installation meets current technical and quality requirements.

TrustMark

Government-endorsed quality scheme. Vetted for technical competence, customer service and trading practice. Not all installers hold this.

Trading Standards Approved

TSI Approved Code. Consumer protection covering fair trading, contracts and complaints handling. Independently assessed.

Competent Persons Scheme

Blueflame membership. Allows self-certification for building regulations compliance without requiring a separate local authority inspection.

NEBOSH Director

Aaron Davies holds a NEBOSH qualification in Health and Safety Management for Construction. Issued June 2025. Unique in our local market.

10 Honest Pricing

What Does Cavity Wall Extraction Cost?

Extraction is priced per property following the borescope survey. Cost varies with property size, the amount of material to remove, the material type, and site access conditions.

Smaller Property

Terraced or Smaller Semi-Detached

£500 – £900

Typical for a terraced property with up to around 50m² of external cavity wall area to treat. Price confirmed following survey.

Borescope survey included
Full extraction on confirmed day
Re-pointing of all drilled holes
Written post-extraction report

Standard to Larger Property

Semi-Detached or Detached

£900 – £1,500+

Typical for a standard semi-detached or detached property. Larger or more complex properties may exceed this range. Confirmed by survey.

Borescope survey included
Full extraction on confirmed day
Re-pointing of all drilled holes
Written post-extraction report

Re-insulation is quoted separately. If the cavity is suitable for re-insulation after extraction and drying, a separate quote for modern cavity wall insulation will be provided. Re-insulation is not part of the extraction price. Finance options are available subject to status.

11 FAQs

Cavity Wall Extraction, Common Questions

Honest answers to the questions we are asked most often.

What cavity wall insulation materials can you extract?

Our extraction service is material-agnostic. We remove every common cavity fill product installed in UK properties: Mineral Wool (MW), Expanded Polystyrene beads (EPS / Airpop), Urea Formaldehyde foam (UF), Polyisocyanurate (PIR), Polyurethane (PUR), and Phenolic (PF). The borescope survey confirms the material type so we bring the correct extraction approach to site. Different fill types behave differently during removal, which is why a general builder cannot do this work, specialist vacuum equipment and the right technique matter.

What is cavity wall extraction?

Cavity wall extraction is the process of removing existing cavity wall insulation that has failed. Typical scenarios include old mineral wool, loose-fill or blown insulation that has become wet, compacted, displaced or contaminated over time. Small-diameter holes are drilled at regular intervals in the external masonry, a high-powered vacuum system draws the failed material out through each hole in turn, and the holes are re-pointed with matching mortar once the cavity is clear. It is a specialist service that requires specialist equipment and cannot be carried out by a general builder.

How do I know if my cavity wall insulation has failed?

The most common signs are persistent damp patches on internal walls that return after treatment, mould that keeps coming back in the same places, and internal walls that feel cold to the touch despite supposedly being insulated. These symptoms can have other causes, which is why we always carry out a borescope survey before recommending extraction. The survey gives visual confirmation of the insulation condition so the diagnosis is based on evidence, not assumption.

How is the extraction carried out?

Small-diameter holes are drilled in the external masonry at regular intervals, following the same pattern used in the original insulation installation. A high-powered vacuum extraction system is connected to each hole in sequence and the failed material is drawn out and collected. Once the cavity is confirmed clear, all drilled holes are filled and re-pointed with mortar matched to the existing finish as closely as possible.

Will the drill holes in my walls be visible afterwards?

The drill holes are filled and re-pointed with mortar that is matched to the existing finish. On most properties the re-pointing is barely visible after weathering. On older or more distinctive brickwork, some variation in mortar colour is possible. We are upfront about this. The holes used are the same diameter and follow the same pattern as the original installation, so the approach is consistent with what was done when the insulation was first put in.

How long does the extraction take?

Most extraction jobs on standard domestic properties are completed within a single working day. Larger properties or those with more complex access may take longer. We confirm the expected timescale with you before the work begins. The borescope assessment is typically a separate, shorter visit carried out in advance.

Can I get the cavity re-insulated after extraction?

In many cases, yes. Once the failed material has been removed and the cavity has been given time to dry out thoroughly (typically several weeks), modern cavity wall insulation can be installed correctly. Re-insulation is a separate service quoted on its own merits after the extraction is complete and the cavity is dry. If the underlying cause of the failure was structural water ingress rather than product failure, we would be honest about whether re-insulation is advisable.

Will extraction definitely fix the damp in my walls?

If failed cavity wall insulation is the confirmed cause of the damp, extraction resolves it in the vast majority of cases. However, damp in walls can have multiple causes, and if the survey identifies a different root cause (structural water ingress, defective guttering, bridging at ground level, etc.) we will tell you clearly. That is why the borescope survey before any extraction work is non-negotiable for us. We will not extract insulation that is in good condition, and we will not tell you extraction will fix something it cannot fix.

My insulation was installed in the 1980s, does that mean it has failed?

Not necessarily. Some cavity wall insulation installed decades ago is still performing well, particularly mineral wool installed correctly in properties with suitable cavities. Age alone is not a reason to extract. The product type matters: urea formaldehyde foam, which was widely used in the 1970s and 1980s, has a much higher failure rate and is known to cause problems in many properties. The best way to find out is a borescope survey, which gives visual confirmation of the current condition rather than relying on age as a proxy.

Cavity Wall Extraction Specialists

Your Walls Are Damp Because the Insulation Has Failed

Specialist Extraction. Proper Survey First. No Guesswork.

What Changes After Extraction

Is Cavity Wall Extraction Right for You?

What Customers Say

From First Call to Clear Cavity

Specialists, Not Generalists

Damp Treated Twice. Still Coming Back. Fixed.

3-Bed Semi, Persistent Damp on Internal Walls Despite Two Previous Treatments

Certified to the Standards That Matter

What Does Cavity Wall Extraction Cost?

Cavity Wall Extraction, Common Questions

Book Your Free Borescope Assessment