Cavity Wall Estimator
Calculate insulation volume and bags for standard UK wall cavities.
Material Volume
Thermal Comfort: Insulating Your Wall Cavities
Internal Warmth
About a third of all heat lost in an uninsulated home escapes through the walls. By filling the cavity with insulating material, you create a thermal barrier that keeps heat inside during the winter and out during the summer.
Our **cavity wall insulation calculator** helps you estimate the volume ($m^3$) of material needed to fill the gap, whether you are using EPS beads or blown wool.
Material Standards
Cost & Savings
A typical semi-detached house in the UK costs between £600 and £1,000 to insulate via injection. However, this can lead to annual savings of up to £300, meaning the measure pays for itself in roughly three years. It is widely considered the best return-on-investment energy measure for older homes.
The Injection Process
Installers drill a series of small holes (approx 22mm) in the mortar joints of your external wall. The insulation is then blown into the cavity under pressure until it is completely filled. The holes are then 'made good' with mortar that matches your existing walls.
Damp & Condensation
If your house has existing damp issues or poor pointing, cavity insulation can exacerbate the problem. It is essential to fix any structural issues or leaking gutters before proceeding with the installation.
Pro Tip: Government Grants
Before paying for cavity wall insulation, check if you are eligible for the **ECO4** or **Great British Insulation Scheme**. Many UK households can get their insulation done for free or with a heavy subsidy.
Cavity Wall FAQ
Professional Assessment Required
Never attempt to install cavity wall insulation as a DIY project. It requires specialist machinery and a formal assessment of the wall's suitability. Incorrect installation can lead to irreversible structural damp issues.