Two different defects, two different parts of the country, one thing in common: the house looks fine at a viewing and the bill is enormous.
Mica (defective concrete blocks)
Blocks with too much mica or pyrite crumble over years. Cracking starts at corners and around windows, then the render maps out the blocks underneath. The Defective Concrete Blocks Grant Scheme now covers six whole counties: Carlow, Clare, Donegal, Limerick, Mayo and Sligo. It also covers designated parts of three more council areas: Fingal, Meath and Wexford. Carlow and the Meath areas were added on 8 July 2026. In Fingal, Meath and Wexford the county name alone tells you nothing: ask the council whether the address is inside the designated area before you rely on the scheme.
To qualify, a home must have been built before 31 January 2020, be the owner’s main residence (or a rental registered with the RTB before 2 November 2021) and not be an unauthorised structure. The grant covers 100% of approved remediation up to €462,000, and the Housing Agency decides which of five options applies, from re-rendering the outer leaf to demolition and rebuild. Ask the seller whether the house was ever tested (core samples, IS 465 assessment) and whether a scheme application was made. A surveyor should say in writing whether they saw the pattern cracking. If the house is in a scheme area, ask for a block test before you sign.
Pyrite
Pyrite in the hardcore under the floor slab swells when wet. Floors lift and crack, doors stick, skirting boards move. Mostly Dublin, Meath, Kildare and Offaly, in houses built about 1997 to 2013 with stone from a handful of quarries. The Pyrite Resolution Board ran the remediation scheme; many affected estates have been fixed and carry a certificate of remediation. Ask for it. A fixed house is fine. An unfixed one in a known estate is a negotiation about the cost.
What checks can and cannot tell you
No public register lists affected houses by address. What the record does give: the county scheme designation, the build year from the BER certificate, and planning history that sometimes shows remediation works. That is what the report flags, with the questions to put to the seller and the surveyor. The rest is a core sample.