We here at Nestor Shanahan Auctioneers know that for many families in parts of Ireland, the words mica and pyrite bring real worry. Defective building materials have caused serious damage to thousands of homes, and while Government schemes now offer substantial support, buyers in affected areas need to be especially careful. The good news is that with the right checks and professional advice, you can buy with confidence. Here is what you should know before making an offer.
Understanding the problem
Although the two terms are often used together, they describe slightly different issues. Defective concrete blocks contain excessive amounts of minerals such as mica or pyrite, which can cause the blocks to weaken, crack and, in severe cases, crumble over time. This problem affects the walls of a house.
A separate issue arises where pyrite is present in the hardcore fill beneath ground floor slabs. When it reacts, it can cause floors to heave and internal walls to crack. This was largely associated with homes built during the boom years in parts of Leinster, including areas of Dublin, Kildare, Meath and Offaly, and has its own remediation scheme.
Which counties are affected?
The Defective Concrete Blocks Grant Scheme originally launched in Donegal and Mayo and has since expanded. According to the Housing Agency, the enhanced scheme is open to affected homeowners in Clare, Donegal, Limerick, Mayo and Sligo, and Wexford and Fingal have more recently been added, with an application to include Tipperary also being progressed. Being in one of these areas does not mean a particular home is affected, but it does mean the issue should be firmly on your checklist.
Know the warning signs
Defective blocks often reveal themselves through cracking in external render, typically in a spider web or map-like pattern rather than a single straight line. Other signs include cracks that widen over time, gaps opening around windows and doors, cracked sills, bulging walls and blocks that crumble when touched. With pyritic hardcore, look for uneven or lifting floors, cracked floor tiles and cracks at the base of internal walls. Fresh paint or newly applied render on an otherwise older property is not necessarily a red flag, but it is worth asking why the work was done.
Commission specialist advice
A standard survey may not be enough in an affected area. Engage a chartered engineer or surveyor with specific experience of defective concrete blocks, and ask whether further investigation is needed. Testing and assessment in this area follows a specific Irish standard, I.S. 465, and can involve taking samples from the walls for laboratory analysis. This adds time and cost, and requires the seller's permission, but it is a small price compared with the potential cost of remediation.
Ask the right questions
Ask the seller when the house was built and, if known, who supplied the blocks. Find out whether the property has ever been tested, whether a grant application has been made and whether any remediation has been carried out. If neighbouring homes built at the same time have been affected, that is important information too. Your solicitor should raise these matters formally in pre-contract enquiries, and any test results, engineer's reports or grant correspondence should be reviewed carefully.
Remediated homes can be an opportunity
A home that has been fully remediated under the grant scheme, particularly one that has been demolished and rebuilt, can offer real peace of mind and modern construction standards. However, it is essential to obtain all completion documentation, engineer's certificates and any warranties, and to confirm that the work was carried out under the scheme's requirements.
Understand the grant scheme
The enhanced scheme provides substantial support to eligible owners. The Government increased grant rates and the overall cap in October 2024, and the maximum grant is now up to €462,000 for a detached home, with lower limits for other house types. Applications are made through the relevant local authority, while the Housing Agency determines eligibility and decides the best remediation option and grant amount. Eligibility rules are detailed, so if you are considering a home that may be affected, check with the local authority or your solicitor whether you, as a future owner, could qualify.
Mortgage, insurance and tax
Speak to your lender and insurer early. Some may ask additional questions or require specific reports before lending on or insuring a property in an affected area. On a positive note, the exemption from Local Property Tax for certain homes damaged by defective concrete blocks has been broadened to reflect changes to the remediation scheme.
Advice for sellers
If you are selling in an affected county, being open and well prepared is your greatest asset. Gather any test results, engineer's reports and grant or remediation documents before going to market. Clear information reassures buyers, helps lenders and avoids delays once a sale is agreed.
The bottom line
Mica and pyrite are serious issues, but they are also well understood, testable and, in many cases, fixable. By recognising the warning signs, commissioning specialist advice and asking the right questions, buyers in affected counties can make informed decisions and avoid costly surprises.
If you would like to discuss buying or selling a property, contact us on 061 415337 or email info@nestorshanahan.ie or visit nestorshanahan.ie.
Disclaimer: This article is based on publicly available information and is intended for general guidance only. While every effort has been made to ensure accuracy at the time of publication, details may change and errors may occur. This content does not constitute financial, legal or professional advice. Readers should seek appropriate professional guidance before making decisions. Neither the publisher nor the authors accept liability for any loss arising from reliance on this material.
