Cavity Wall Insulation FAQs

How does cavity wall insulation work?

We inject insulation material into the cavity (gap) between your inner and outer walls. This helps retain heat inside the building, reducing heating bills and improving overall comfort.

What homes are suitable for cavity insulation?

Most homes built between 1930 and 2006 with cavity walls are suitable. We survey your home to check cavity width, wall type, moisture risk and past insulation work before proceeding.

What materials do you use?

We use NSAI-certified bonded polystyrene bead systems in most homes. These beads are breathable, fire-retardant, water-resistant and have a lifespan of over 25 years.

How is cavity wall insulation installed?

Small holes (about 22mm) are drilled into the external walls. We inject insulation beads mixed with bonding agent, then seal and colour-match the wall finish. It's a fast, tidy process done from outside.

Does the insulation settle over time?

No — the bonding agent holds the beads firmly in place, preventing any settling or sagging inside the cavity over time.

Will cavity wall insulation cause dampness?

No — if installed correctly, it actually helps reduce condensation and surface mould by keeping internal walls warmer. We always carry out a moisture risk assessment before any job.

How much heat can cavity insulation save?

Cavity wall insulation can reduce heat loss through external walls by up to 35%. Most homeowners also notice faster warm-up and more consistent room temperatures.

How long does installation take?

Most cavity wall installs are completed in 2–4 hours, depending on home size and accessibility. Larger homes or complex layouts may take a little longer.

Will the wall finish be affected?

No — we aim to drill into mortar joints where possible, and we colour-match the hole repairs to blend with your existing render or dash finish.

What’s the difference between bead and foam insulation?

Bonded bead is ideal for standard cavities. Foam-fill can be used in narrow or irregular cavities. We recommend the best option after inspection.

Will cavity insulation help with condensation?

Yes — by warming internal surfaces, cavity wall insulation can reduce surface condensation and mould risk. That said, good ventilation is still essential.

Can you insulate just part of a home?

Yes — we can insulate one wall, an extension, or other specific elevations as needed. We’ll define this clearly in the survey and quote.

Are SEAI grants available?

Yes — cavity wall insulation is eligible under SEAI’s Home Energy Grants. Grant amounts vary based on house type. We’ll guide you through the application and issue all required paperwork. See grant details.

Do you provide documentation?

Yes — every job includes a full handover pack with insulation system details, photo evidence (if needed), and your warranty certificate.