Cavity Insulation Extraction Costs

Cavity Insulation Extraction Costs2021-12-06T15:20:00+00:00

Cavity Wall Insulation Extraction Costs, Defects Investigations.

I-CAN (Insulation Consultancy & Analysis) carried out a survey of indicative costs of remedial Works associated with inappropriate and defective cavity wall insulation measures (CWI).

Fig 1. Cavity Insulation Extraction

Fig 2. Removal of Debris and Insulation from Cavity


Around half (13.5 million) of the existing housing stock in the United Kingdom is pre-war and pre-Building Regulations and suffer from:

  • poor construction

  • old, cracked external leaking walls

  • poorly maintained soft mortar joints

  • damp or water in the bottom of the cavities

  • damaged or missing damp proof courses

  • failed, inadequate or corroded wall ties

  • narrow or uneven width cavities

  • part rubble filled cavities

  • and many of these homes are also in severe or very severe wind driven rain exposure

  • or are in flood risk areas

and should not be insulated with inappropriate standard cavity wall insulation (fibre, bead) measures without substantial remedial work having been carried out to make good the defects prior to installation. If your home is in a severe or very severe wind driven rain exposure region or in a flood risk area you should consider incorporating flood resilient (FRe) materials in place of standard materials.

The background to the installation of these inappropriate measures is that over the last fifteen plus years there have been several insulation schemes funded either directly by government (Decent Homes, CERT, CESP, etc) or through an Energy Company Obligation (ECO) placed on the major fuel utilities. Whilst there has been a certain amount of impositions placed on the installers under the schemes, there has not been a consistent policing of work standards and little in the way of adequate technical monitoring inspection regimes.

Fig 3. Damp and Black Mould

Fig 4. Damp and Black Mould

There is now a growing number of homeowners’ complaints in relation to inappropriate standard (fibre, bead) cavity wall insulation measures concerning condensation, damp, wet and saturated insulation, mould, and health related issues which require one or a combination of cavity wall insulation extraction, wall tie replacement and remediation re-fill insulation contractor services.

Of main concern is the health issue. The primary purpose of cavity wall insulation is to make a house warmer which in turn assists with fuel poverty, releasing money for residents to heat their home better with the well documented associated health benefits including a reduction in mould growth which impacts respiratory conditions so severely. Once the fibre or bead insulation becomes wet the insulant no longer acts as an insulant, in fact the reverse happens and the wall will perform considerably worse in thermal terms than an unfilled cavity. Houses can become extremely damp as a result of the insulation being saturated to the point where rooms are uninhabitable or residents may have to move all possessions away from the internal surfaces of external walls to prevent them from being destroyed by damp and black mould.

There is also growing evidence that the number of requests for cavity wall insulation removal following Building Surveys for mortgage purposes has also greatly increased. Some insurance policies do not provide cover for damage caused by property age or maintenance-related issues, and homeowners are also being advised that inappropriate standard (fibre, bead) cavity insulation measures may invalidate leases and house insurance policies.

Fig 5. Unacceptable Mortar Snots and Insulation within Cavity post Cavity Clearance

Cavity extraction companies carrying out removal of defective saturated cavity insulation work are reported to be springing up all across the country claiming to be expert extraction companies. Many of these companies are reported to be employing the same building surveyors and technicians who were claiming to be expert advisors and installers and who were responsible for the defective installation work in the first place.

Survey of Costs

Typical Costs associated with Cavity Insulation Extraction

I-CAN together with a number of Local Authorities conducted trials to try to establish indicative typical costs in relation to extraction of inappropriate standard (fibre, bead) cavity insulation measures in homes with reported damp insulation problems and consequent health and safety risks to the occupants including black mould, and structural issues including corroded wall ties, cracking and bulging and high risk to the lives and of injury to both occupants and pedestrians from brick detachment and collapse of the outer leaf of brick walls, etc.

Early indications based on mid-terrace properties were typically:

Costs were found to range from range from £380 – £930 average cost £575
Costs for mid terrace were found to range from £1,250 – £1,700 average cost £1,475
Total (Ex Vat) average cost £2,050

Remediation Re-fill

Homeowners in severe or very severe wind driven rain exposure regions or in a flood risk areas should avoid incorporating materials which absorb or retain water and should consider incorporating flood resilient (FRe) materials in place of standard cavity wall insulation (fibre, beads) materials.

For details of Standards for materials and products that relate to construction and flood resilience go to standards

Other associated typical indicative costs:

Based on an end terraced property:

  • Removal of rubble at the bottom of a cavity; £150 – £600

  • Removal of mortar dropping on wall ties; £30 – £600

  • Faults in pointing; £50 – £2500

  • Spalled / damaged brickwork; £30 – £1000

  • Poor ventilation in the cavity; £30 – £450

  • Thermal bridges; £150 – £3500

  • Structural issues (eg subsidence, bowed walls, cracks etc); £500- £7000

  • Faulty or missing damp proof course; £300 – £3500

Please Note

The above costs do not include costs in connection with replacing decorations, carpets, curtains, furniture, etc destroyed by damp and mould conditions.

Costs should also be established in connection with different construction methods, and for semi-detached, end terrace and detached properties.

As indicated above, the costs associated with extraction and removal of inappropriate materials and prolonged drying out can be exorbitant and highly disruptive. In addition, the work may result in unsightly damage to the external appearance of the property, and costs, therefore, are not just measured in terms of money, but also in terms of time, aesthetics, inconvenience and heartache to families.

Many homeowners living in fuel poverty in the worst housing are having to incur increased fuel bills over many years in connection with damp cold walls caused by inappropriate standard cavity insulation measures and may now be faced with enormous bills for cavity wall insulation extraction and remedial works to their properties.

If you have had cavity wall insulation (CWI) carried out on your home which has caused damp, black mould, or health related issues, etc, and you require the assistance of a chartered building engineer please click here to contact us.