Timeline & evidence

Why homes are failing, and what the science actually shows

A record of the research, the government response and the homeowner experience, newest first. Homeowners were told for years that the science was settled. It was not.

2017the year official policy was set, on limited evidence

2023peer review overturns the mica hypothesis

ISAinternal sulfate attack, now the confirmed mechanism

6peer-reviewed studies underpinning this page

2025

Public consultation

Consultation opens on the draft revision of I.S. 465

The standard governing how damage is assessed is reopened for revision
Homeowner groups and engineers submit evidence on sulfate attack

Why it matters: I.S. 465 decides what counts as damage and therefore what the State will pay for. A standard written around the wrong mechanism produces the wrong answer, however carefully it is applied.

NSAI consultation documents

2024

Scheme change

Preliminary adjustments to the scheme are announced

Grant caps and rates are revised, but the cost basis is unchanged
Remediation options remain tied to the 2017 assessment framework

Limitation: the adjustments moved figures without moving the science underneath them, so shortfalls persisted.

Research

Government-funded research confirms internal sulfate attack

State-commissioned work identifies ISA as a primary deterioration mechanism
Findings align with what homeowners’ own testing had shown years earlier

Research summary

2023

July 2023 · Oireachtas

Committee hears that the governing policy is obsolete

Experts tell the committee the scheme rests on superseded science
Calls are made to revise I.S. 465 and the assessment methodology

Committee transcript

March 2023 · Peer review

Peer-reviewed research overturns the mica hypothesis

Muscovite mica is shown not to be the principal cause of block failure
Pyrrhotite and other iron sulphides are identified as the driver, expanding as they oxidise

Critique: the State had built a decade of policy, naming and public messaging around “mica”. Homeowners were assessed against a mechanism that the evidence no longer supported.

Construction & Building Materials (2023)DOI record

2020–2022

Homeowner-led

Homeowners fund their own testing and find iron sulphides

Families pay for independent petrographic analysis of their own blocks
Results repeatedly show sulphide content inconsistent with the official explanation

Impact: the correction to the science came from the people living in the houses, not from the bodies responsible for the standard.

2017

Policy origin

The official response is built on limited evidence

An expert panel attributes damage principally to excessive muscovite mica
Sampling is narrow and sulphide testing is not carried out at scale

Consequence: every rule, rate and remediation option that followed inherited this starting point.

Analysis

State negligence and the homeowner fight

Block standards were not effectively enforced during the construction boom
Market surveillance failed to catch defective product before it reached homes
The burden of proof was placed on homeowners, at their own expense
Policy was not revised promptly when the science changed

Comparison

Learning from Canada

Trois-Rivières, Québec faced near-identical pyrrhotite failures from 2007
Testing protocols and remediation standards were developed there years earlier

Canadian expertise, including work shared by Debra McCoy, was available to Ireland well before the mica hypothesis was corrected here.

Sources