Question 1

Why does cavity wall insulation fail?

Accepted Answer

Most failures are due to installer error during the 2008–2016 government schemes. Properties in exposed locations, with narrow cavities, defective mortar joints, or existing damp were filled regardless of suitability. Once saturated, mineral fibre provides no insulation value and actively causes damp.

Question 2

How much does cavity wall insulation removal cost in London?

Accepted Answer

Cost depends on property size and fill type. Most London homeowners pay between £1,500 and £4,000 for a full extraction. We provide a written fixed-price quote after a free borescope survey with no call-out fees and no obligation to proceed.

Question 3

Will removing the insulation help me sell my house?

Accepted Answer

Yes — mortgage surveyors and RICS valuers routinely flag cavity wall insulation as a material risk. A completion certificate from an OSCAR-approved extractor with cavity photographs is the evidence lenders and solicitors require. In many cases, removal is a condition of sale.

Question 4

Is the borescope survey really free?

Accepted Answer

Yes, completely free and no obligation. One of our surveyors visits your property, drills a small inspection hole, and uses a camera to check the cavity condition and fill type. You'll get an honest assessment and a written quote on the spot.

Question 5

Can I claim the cost back through my CIGA guarantee?

Accepted Answer

If your insulation was installed under a government scheme, the installer was required to register a CIGA (Cavity Insulation Guarantee Agency) guarantee. If the installation was defective, you may be entitled to remedial work at the installer's cost. We check this for every property and help you submit a claim where eligible.

Question 6

How long does cavity wall insulation removal take?

Accepted Answer

For a standard semi-detached property, extraction takes one day on site. Larger or detached properties may take two days. We begin with a borescope inspection, move to extraction, then finish with mortar repointing. You can remain in your home throughout.

FAQ | WL Cavity Wall Care