Cavity wall insulation being injected into an Irish home

Cavity Wall Insulation
in Ireland

Most Irish homes lose heat through unfilled cavity walls. Get matched with an experienced local installer and receive a free, no-obligation quote.

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What Is Cavity Wall Insulation?

Cavity walls are made of two layers of brick or block with an air gap in between. This construction is standard in Irish homes built from the 1930s through the early 2000s. While the cavity was originally designed for moisture protection, it also lets a huge amount of heat escape. Filling it with insulation stops that heat loss while maintaining the wall's moisture resistance.

Fill the Gap

Most Irish homes built between the 1930s and 2000s have cavity walls with a 50-100mm air gap. Filling that gap with insulation makes a real difference to heat loss.

Minimally Invasive

Small holes are drilled into the outer wall, insulation is injected, and the holes are patched the same day. No interior disruption and no scaffolding needed for most homes.

Fast Process

Most homes are fully insulated in 4-6 hours. No need to take a day off work. The entire job is done from the outside with minimal noise.

Lower Bills

Cavity wall insulation can reduce your heating costs by up to 25%. Combined with SEAI grants, the payback period is often under 3 years.

How Cavity Wall Insulation Works

The process is straightforward and causes minimal disruption to your home. Here's what to expect:

1. Pre-installation survey

The installer checks your wall type, cavity width, and condition. They'll look for any damp issues or obstructions that might affect the work. This usually takes 30-60 minutes.

2. Drilling injection points

Small holes (about 22mm) are drilled through the outer wall at regular intervals, usually through mortar joints. This is done in a grid pattern to ensure full coverage of every wall section.

3. Bead injection

Bonded bead insulation is pumped into the cavity under pressure. The beads expand slightly and bond together, filling every gap and corner. This is the most common method in Ireland and provides strong thermal performance.

4. Finishing

The drill holes are filled and colour-matched to your existing mortar. Within a few months of natural weathering, the patches become virtually invisible.

Cavity Wall Insulation Costs in Ireland

Costs depend on the size and type of your home. Cavity wall insulation is one of the most affordable insulation upgrades, especially when combined with SEAI grants.

Property Type Typical Cost
Apartment / mid-terrace €700 – €1,200
Semi-detached €1,000 – €1,800
Detached bungalow €1,200 – €2,000
Large detached €1,500 – €2,500

Prices are estimates based on typical Irish installations in 2026. Actual costs depend on wall area, cavity width, and access. SEAI grants of up to €1,800 may apply for cavity wall insulation (up to €2,300 for qualifying welfare recipients). Request a quote for an accurate price.

Frequently Asked Questions

How do I know if my house has cavity walls?
Most Irish homes built between the 1930s and early 2000s have cavity walls. You can check by measuring wall thickness at a door or window opening. Cavity walls are typically 270-300mm thick (about 11 inches). Thinner walls (around 230mm / 9 inches) are likely solid. An installer can confirm during a survey.
Will cavity wall insulation damage the outside of my house?
No. The injection holes are small (about 22mm diameter), drilled in a grid pattern through the mortar joints. They're filled and colour-matched after injection. Within a few months of weathering, they become virtually invisible. The process doesn't affect the structural integrity of your walls.
How long does cavity wall insulation last?
Cavity wall insulation is designed to last the lifetime of the building. Bonded bead insulation, the most common type used in Ireland, doesn't settle, compress, or degrade over time. Once installed, you shouldn't need to think about it again.
Is my house suitable for cavity wall insulation?
Most cavity wall homes are suitable, but some conditions may need attention first. Homes with severe rising damp, cracked render, or very narrow cavities (under 40mm) may need remedial work before insulation. Exposed coastal properties may require different specifications. A pre-installation survey will identify any issues.
Can cavity wall insulation cause damp?
When installed correctly in a suitable property, cavity wall insulation does not cause damp. In fact, it can reduce condensation by keeping internal wall surfaces warmer. Issues only arise if insulation is installed in walls with pre-existing damp problems or severe exposure to driving rain. A proper survey beforehand ensures your home is suitable.

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