Cavity Wall Insulation in Wolverhampton & the Black Country

Free under ECO4 for eligible homesFrom £450Saves around £295/year

Cavity wall insulation is the process of filling the gap between the two layers of an external wall with an insulating material, usually mineral wool fibre or expanded polystyrene (EPS) beads, injected through small holes drilled into the mortar joints. It suits properties built from roughly the 1920s onward, which were constructed with two brick skins separated by an air cavity that was left empty. Around 70% of homes in Wolverhampton and the wider Black Country are cavity-walled, and many still have unfilled cavities. The work on a typical semi-detached house takes two to three hours, the drill holes are filled and colour-matched, and there is no internal mess. The Energy Saving Trust estimates cavity wall insulation saves an average semi-detached home around £295 a year on heating bills. For households eligible under the ECO4 scheme, cavity wall insulation is fitted free of charge.

How cavity wall insulation works

Cavity wall insulation works by trapping a layer of still air within the wall cavity, which slows the movement of heat from the warm inside of your home to the cold outside. An installer drills a pattern of small holes, around 22mm across, into the mortar joints of the external wall. Insulation is then blown or injected under pressure until the cavity is completely full, the holes are sealed with mortar colour-matched to your brickwork, and the job is finished. There is no disruption inside the house and no need to move furniture.

Two materials dominate in the Black Country. Blown mineral wool is the most common, offering excellent thermal performance and fire resistance. EPS beads bonded with adhesive are preferred for more exposed properties because they resist water tracking across the cavity. Your surveyor recommends the right material based on your wall construction and exposure rating.

Is your property suitable?

Cavity wall insulation suits the large stock of interwar and post-war semis and detached homes across Penn, Tettenhall, Aldridge, Halesowen and the planned estates of Telford. The property needs an unfilled cavity of at least 50mm, walls in sound condition, and an exposure rating that the survey confirms is acceptable. Homes with solid 9-inch brick walls, common in the Victorian terraces of Whitmore Reans, Caldmore and Netherton, cannot take cavity insulation and need solid wall insulation instead. Some non-traditional post-war system builds in Bushbury and Bloxwich need a specialist assessment before any work goes ahead.

Cost and savings

Paid privately, cavity wall insulation runs from about £450 for a small semi to £700 or more for a larger detached house. The Energy Saving Trust puts the typical annual saving at around £295 for a semi-detached home and more for detached properties, which means the work usually pays for itself inside two to three years even without funding.

For most homeowners in our area, the more important number is zero. If your household qualifies under the ECO4 scheme or the Warm Homes Local Grant, cavity wall insulation is fully funded and costs you nothing. Around 59% of Wolverhampton homes fall within the EPC bands that grant funding targets, and we check your eligibility before quoting.

The process from survey to completion

Free, no-obligation survey to confirm your cavity is suitable and check grant eligibility.
We confirm your funding route and book an installation date that suits you.
Installation on the day, typically two to three hours for a semi, with no internal mess.
A guarantee is registered, usually a 25-year CIGA guarantee, covering the workmanship.

Cavity wall insulation pairs naturally with loft insulation. Done together, the two measures often save a typical home around £650 a year and are frequently funded as a package under ECO4. To see which measure to prioritise, read our guide on cavity wall versus loft insulation.

Cavity Wall Insulation near you

We fit cavity wall insulation across the Black Country and Telford. Choose your area for local detail and grant routes:

Frequently asked questions

How do I know if my walls have a cavity?

Homes built from around the 1920s onward usually have cavity walls. A quick check is the brick pattern: cavity walls show bricks laid lengthways in an even pattern (stretcher bond), while solid walls show an alternating pattern with some bricks laid end-on. Wall thickness over about 260mm at a window or door reveal also suggests a cavity. We confirm this for certain with a borescope at the free survey.

Will cavity wall insulation cause damp?

Properly installed cavity wall insulation does not cause damp. Problems only arise when insulation is fitted to an unsuitable property, for example one heavily exposed to driving rain or with existing defects. That is why a PAS 2030 survey checks suitability first. We will tell you honestly if your property is not a good candidate.

How much does cavity wall insulation cost in Wolverhampton?

Without a grant, cavity wall insulation typically costs £450 to £700 for an average semi-detached house, more for a detached property. Under the ECO4 scheme, eligible households pay nothing. We check your grant eligibility before quoting any price.