After the roof, your walls are where most of your home's heat is lost — up to a third of it in a home with empty cavity walls. Filling that gap is quick, clean, and one of the most effective upgrades you can make. Free survey, fitted by a TrustMark registered team.
Most homes built from the 1930s onwards have two layers of brick or blockwork with a gap — a cavity — between them. In an uninsulated home, that gap is just air, and heat passes straight through it to the outside. Cavity wall insulation fills the gap with an insulating material, injected through small, neat holes that are made good afterwards, so the warmth stays inside.
In a home with uninsulated cavity walls, around 33% of heating can escape through the walls. Filling the cavity is one of the highest-impact upgrades available.
According to the Energy Saving Trust, around a third of the heat lost from an uninsulated home escapes through the walls — so filling the cavity is one of the higher-impact upgrades available. They put the typical installed cost in Great Britain at around £2,700, with many suitable homes recovering that cost through lower bills within about five years.
These are Energy Saving Trust estimates at 2026 prices. Your actual saving and cost depend on your home's size, wall area, condition and region — which is exactly what our free survey establishes before we quote.
Most homes built between roughly 1920 and 1990 with unfilled cavity walls are suitable, but it isn't right for every property — homes exposed to driving rain, or with existing damp, need careful assessment first. That's exactly what our free survey is for. We check your wall construction, cavity width and condition before recommending anything, because cavity insulation done in the wrong property can cause more problems than it solves.
It's one of the least disruptive jobs we do. Our installers drill a pattern of small holes in the external mortar, inject the insulation under controlled pressure until the cavity is full, then fill the holes so they blend with your existing brickwork. Most homes are finished in a few hours, with no mess inside and nothing to move.
We check your wall type, cavity and condition to confirm your home is suitable.
If it's right for your home, you get a fixed quote. If it isn't, we'll tell you straight.
Neat injection through small holes, made good afterwards — usually done the same day.
Book your free cavity wall survey. We confirm suitability, give you a fixed quote, and call back within the hour.