Cavity wall insulation removal: cost, the CIGA claim and who to call

What it is

Cavity wall insulation fills the gap between two layers of an external wall. It usually works well, but in exposed or unsuitable walls it can slump or let rain bridge the cavity, causing damp on the inside wall.

This page is about removal, cost and the guarantee route. For the signs of failed cavity wall insulation and why it fails, see the HomesAndHedge guide linked below.

The survey and the work

A survey first confirms the insulation is genuinely the cause of the damp, since not all cavity damp comes from the insulation. A borescope inspection through small holes can show slumped or saturated material.

Removal, or extraction, is done by drilling access holes and using specialist equipment to draw the material out, after which the cavity is left to dry before any decision on re-insulating.

The CIGA route matters here: if the original installation came with a CIGA guarantee, problems caused by faulty installation may be covered, so check the guarantee before paying for removal yourself.

Cost

Survey / borescope inspection

Get a quote Confirms the insulation is the cause before any extraction.

Extraction

Get a quote Driven by the wall area, the material type and access.

Via a CIGA claim

Potentially covered If the original install had a CIGA guarantee, faulty-installation problems may be covered (CIGA).

Before paying for removal, check whether the original installation carried a CIGA guarantee, because a valid claim can cover faulty-installation problems. Otherwise costs depend on wall area, material and access, so get a survey and quote.

Who it is for

• Homeowners with damp on internal walls that a survey has linked to failed or slumped cavity wall insulation.
• Owners whose cavity insulation was installed under a guarantee and who want to check the CIGA claim route first.
• Buyers or sellers where damp linked to cavity insulation has been flagged in a survey.

The mortgage and sale angle

• Damp linked to failed cavity insulation can be flagged in a mortgage valuation, so resolving it, and documenting the fix, is what keeps a sale on track.
• The money-saving angle is the CIGA guarantee: the Cavity Insulation Guarantee Agency provides a 25-year guarantee on registered installations, so a faulty install may be put right at no cost to you (CIGA).
• A buyer reassured by evidence the cavity has been extracted and dried, or repaired under guarantee, is more likely to proceed.

How to choose a vetted specialist

• Use a specialist who surveys with a borescope and confirms the insulation is the cause before recommending extraction.
• Check the CIGA guarantee status of the original install first; the CIGA website explains how to make a claim.
• Get the extraction scope, drying period and any re-insulation advice in writing, and check the firm on Companies House.

Frequently asked questions

Sources

• CIGA (Cavity Insulation Guarantee Agency)