Bonded bead problems

Settled or missing fill

A cavity must be filled to its full depth, at every hole. SEAI's standards say thermal imaging can show areas that have been missed or where the filling material has settled, and they require a borescope check on every drill hole during the install so the pattern matches the certificate (SEAI Domestic Technical Standards and Specifications, v4.0, July 2026, clause 6.1, read 29 October 2026). If an upstairs room on an outside wall stays cold after the job while the rest of the house is warmer, a thermal image on a cold day shows whether the fill stops short. A UK insulation guide describes the same fault from installers who skipped the binder: beads settling to the bottom of the cavity, leaving the upper wall uninsulated (TheGreenAge, UK).

What to do: ask the installer for the installation check sheets and the second borescope survey, which SEAI's standards require them to keep. Ask them to re-check the cold area with a borescope and top it up.

Bead where it shouldn't be

Bead is small and light, so an open cavity top, an unsleeved vent or an unbrushed party wall lets it travel. SEAI's standards require the cavity to be closed at the top of the wall and above openings before pumping, brushes at party walls so bead doesn't migrate between properties, any bead blown into the attic removed and the leak sealed, and the meter box checked so bead can't touch the electrical cables (SEAI technical standards).

What to do: bead in the attic or the meter box after a job is the installer's to clear. The ESB Networks cable must not be in contact with the insulation, so if you find bead in the meter box, say so to the installer and don't open the box yourself.

Blocked vents and flues

Wall vents, underfloor vents and the air supply to a gas, oil or solid fuel appliance must keep working. SEAI's standards say ventilation openings are checked for obstruction by the insulant, flues are tested before and after, and the installer must tell the homeowner in writing about any ventilation they consider inadequate (SEAI technical standards). A room that feels stuffy, condensation that started after the job, or a fire or stove that draws badly are the signs.

What to do: look at each outside vent for bead behind the grille. For a flue or a solid fuel appliance, don't test it yourself: ask the installer to repeat the smoke test, and a registered gas installer if a gas appliance is involved.

Damp that appeared after filling

Bead sheds water, but it can bridge a cavity where the outer leaf already lets rain through, where mortar or rubble sits in the cavity, or where the wall is badly exposed. SEAI's standards require exposure to wind-driven rain to be assessed before the fill is chosen, with Met Éireann's driving rain map as the reference, and any defect that could let water in to be recorded and fixed first (SEAI technical standards; Met Éireann). One Irish cost guide puts it the same way: if the wall already has water penetration, bead can bridge moisture inwards (ShamFix).

What to do: the steps are on cavity wall insulation and damp. Note where and when it shows, check the gutters and render on that wall, and call the installer back with the survey report in hand.

Binder that didn't set

SEAI's standards say low temperatures may affect the adhesive that bonds the beads, which may compromise the insulation, and that a flow-rate test keeps the bead-to-adhesive ratio right so beads don't leak (SEAI technical standards). Loose bead pouring out when a wall is drilled later, for a vent or a cable, is the sign. Bonded bead is meant to stay put when drilled.

What to do: the installer's records must include the bead and adhesive test results. Ask for them, and for the installation date against the weather that day.

The wrong wall was filled

SEAI's standards say cavity hollow block walls are not suitable for cavity wall insulation and timber frame homes cannot be cavity insulated (SEAI technical standards). A hollow block wall has no continuous cavity, so pumping it fills some blocks and not others. One Irish building magazine noted that companies in Dublin have offered to pump-fill hollow block walls (Passive House Plus). In a timber frame wall the cavity keeps the frame dry.

What to do: if you suspect your wall is hollow block or timber frame and was pumped, get an independent survey. For a timber frame wall, removal is usually the advice: see cavity wall insulation removal.

A top-up over old mineral wool

SEAI's standards do allow the residual cavity behind old rigid boards to be filled, with at least 40 mm clear everywhere, but they say cavity walls with existing partially filled mineral wool are not recommended for top-up insulation (SEAI technical standards). A bead top-up over slumped wool can leave the same cold bands as before.

Who to go to

1. The installer first.Under NSAI's scheme they keep a register of installations and customer complaint records, and must give you the Agrément certificate, the warranty and an installer's declaration. Put the problem in writing with photos and dates.
2. The certificate holder.The system's Agrément certificate names the company whose product and method were used. The warranty is usually theirs.
3. NSAI.NSAI audits approved installers about once a year and removes those who don't comply from its web register. Its register shows whether your installer is still approved.
4. SEAI, for a grant-aided job.SEAI may inspect grant-aided work, and the installer must keep survey sheets, borescope results and test records for SEAI to see.

NSAI Agrément CWI installer scheme, D-IAB-003 revision 5, read 29 October 2026; SEAI technical standards.

Before the job, not after

Every problem above is easier to avoid than to fix. The survey report with two borescope holes per elevation, the exposure check, the sleeved vents and the declaration at the end are all required of a registered installer. Pumped insulation, step by step lists what to expect, and the grant check puts you in touch with one SEAI-registered contractor who covers your area.

Questions people ask