Skip to main content
Man carrying out cavity wall insulation installation.

Why cavity wall insulation?

Around 35% of the heat in your property escapes through the walls.

Save energy and keep your valuable heat in for longer!


Cavity wall insulation

Cavity wall insulation wrapped and unwrapped

Using premium insulation

We use Knauf Supafil® 40 – a non-combustible glass mineral blowing wool system which offers excellent thermal performance. Our cavity wall insulation is water-repellent, and BBA-certified as a high-quality, reliable product that is rot-proof, durable and non-toxic in the event of a fire. No chemicals are added to the insulation during the installation process.

We can install your insulation in all weather conditions (even below 5°C), making it durable, even for properties frequently exposed to rain and wind.







Man drilling holes to install cavity wall insulation.

Following a professional process

Before we start work, our installation team will complete pre-installation checks, including combustion appliance and ventilation tests when necessary.

We then drill 22mm (as small as a 20 pence coin!) injection holes into the wall in a diamond pattern to ensure that insulation will evenly and consistently fill the cavity. Once drilling is complete, we blow the insulation into the cavity at low pressure, completely filling the wall.

Once this is complete, we fill the drill holes using a mortar of a similar type and colour to the rest of the wall, so that they blend in unobtrusively. We then undertake a post-installation check to make sure that all works are completed thoroughly. This will include repeat combustion appliance smoke tests and to ensure that all under-floor and combustion vents are clear.

Qualified insulation company

By Viridian’s insulation experts

Our cavity wall insulation is always installed by our own trained and certified installers, who are also qualified to carry out combustion appliance checks.

As a business, we are members of the IAA’s ‘CWISC’ scheme, an affiliation that carries two benefits. Firstly, you can be completely confident in the quality and effectiveness of the work we’ve carried out. Secondly, you won’t need to inform your local authority before the work is completed (or pay the building notice fee, which is usually around £250).

Your new cavity wall insulation is guaranteed by the IAA for 25 years. For more information, read here.



We operate in Kent, Sussex, Surrey, and Greater London and offer bespoke, professional services that add value to your home.

Read our blog or visit the Viridian Facebook page to learn more about insulation, cavity wall insulation, what we do and how we work.


Watch our cavity wall insulation video!

Essentials & Extras

Man cutting out a brick for access to carry out cavity wall insulation removal and cleaning.

Cavity wall cleaning

Wall cavity cleaning should be part of any house maintenance routine, and is essential for preparing cavity walls for insulation.

Man carrying out cavity wall insulation removal.

Cavity insulation removal

Our insulation experts can safely extract and remove existing insulation material.

Man holding up a roll of loft insulation.

Loft insulation

Save energy and keep heat in for longer: we fit 270mm-deep insulation using low-dust, non-itch, 80% recycled material that lasts for decades.