Cavity Wall Extraction & Cleaning

Why Might You Need Your Cavity Wall Insulation Removed?

When the right material is correctly installed, cavity wall insulation will help your home stay warm, safe and energy efficient.

However, cavity wall insulation can cause penetrating damp, mould and condensation if:


  • It’s old and worn
  • It was installed incorrectly
  • Your home is in a high exposure area (find out if yours is)
  • The cavity was not clear before the insulation was installed
  • The structure of your home is not suitable for cavity wall insulation
  • You have damaged walls such as cracks in the brickwork, render or pointing
  • Blockages have entered the cavity because of building works or home improvements


  • Gaps in the insulation allow heat to escape and damp to penetrate
  • If the insulation gets wet it will act as a sponge, drawing water across and holding it against your walls
  • The insulation can prevent adequate ventilation and cause damage to, for example, a steel frame, suspended wooden floors and wall ties

It may take a few years before you notice anything but damp could still be damaging your walls before it becomes obvious. It’s likely your energy costs will be rising too, as your heating will have to work harder to maintain a comfortable temperature.

Check Out Our FREE Guide On Cavity Wall Extraction...

So, why choose Evolve?

If you think your cavity wall insulation may be damaging your home we can help. We can:

1. Carry out a heat loss survey to see if your cavity wall insulation is damaging your home

2. Advise you on how any problems we find can be resolved

3. Remove problem cavity wall insulation

4. Completely clear every elevation of any other materials or blockages

One of our Directors Gary Randle developed the system that we use to remove your cavity wall insulation, which is in common use across the industry. The BBA originally approved this process in 2009, reapproving it in 2015.
Here’s our 10 step system which was designed to get a quality job done with the least interruption to you and your home…

1 – We undertake a thorough survey of your home, including the condition of your external and internal walls and any existing areas of damp. We can then let you know how much it will cost to clear your cavities.

2 – We prepare the site and erect scaffolding if necessary.

3 – We create 5 – 10 openings at damp proof level in the external wall by removing bricks at predetermined distances.

4 – We fix specially designed extraction covers to the openings and attach an extractor.

5 – We drill a series of holes in the mortar line or render and use air pressure to force the insulation materials down to the extractor.

6 – We inspect the cavity at regular intervals throughout the extraction using a 360video boroscope that gives us a 2m view in every direction.

7 – When the extraction is complete and we’ve confirmed all the cavities are completely clear we reinstate the walls and return your home to its original state.

8 – We clear and clean the site so you don’t even notice we’ve been.

9 – We carry out a final inspection of your property.

10 – Our technician fills out and signs a completion certificate, which we ask you to sign as well.

The prices for cavity wall insulation will vary depending on the size of your house and whether there are grants available in your area which may cover the entire cost of the insulation or a significant portion of it. Below are some estimated prices for installing cavity wall insulation in different types of houses:

Size Of Property Price
Flat £330
Mid-terrace house £370
Bungalow £430
Semi-detached house £475
Detached house £720

Our Price Match Promise: Although we only install the best quality cavity wall and loft insulation, we match the price of cheaper, less effective materials!

We can also assist you with any grants that are available to help with the costs of the insulation.

Why May Your Cavity Walls Also Need To Be Cleaned?

Cavity walls are designed to prevent water penetrating the internal walls of your home. The air space between the inner and outer walls allows any water that does get in to drain down to the footings.

However, for this to work the cavity must be completely clear. 
NB: The only exception to this is when an appropriate insulation material is expertly installed.

How could a cavity become blocked?

The cavity may become blocked because:

  • It was not cleared correctly when the house was constructed
  • Debris got in during building work, such as replacing windows or fitting a conservatory
  • Debris got in during improvements and repairs, such as fitting a balanced flue boiler system or a vent

This debris can form a bridge that carries moisture across to the interior of the house, which in time will cause penetrating damp and mould.

Therefore, even if you’re not planning on having cavity wall insulation installed, it’s vital that the cavities of your home are clear.

1. Contact

Book a property survey appointment or call us and we will arrange for your local team to contact you.

2. Inspect

Our surveyors will discuss any problems with you & provide you with a quote and recommendations.

3. Remove

Our qualified technicians will remove any hazardous material from your home, with the least disruption.

4. Upgrade

Our technicians will then install the best quality materials into your home for an unbeatable price

We can also help you with the following services:

Need Your Cavity Walls Extracted?