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Muscovite caused obvious defects in the building blocks used in at least 5,000 houses in the northwest, causing cracks in thousands of buildings. Photography: Joe Dunn.

On Tuesday, Parliament will stage a protest at the Dublin Conference Centre, calling for a mica remediation plan for thousands of homeowners in the northwest. What is the point of contention?

Mica is a type of mineral found in rocks excavated underground and in quarries. Muscovite, biotite and phlogopite are the three most common mica group minerals found in rocks, and therefore also exist in building blocks.

Muscovite caused obvious defects in the building blocks used in at least 5,000 houses in the northwest, causing cracks in thousands of buildings. A video posted online shows that the load-bearing block is teetering in the hands of the homeowner.

Based on the experience of the Mica Action Group and the report of the concrete block expert group released in 2017, mica seems to absorb water from the environment. In some cases, the exterior walls absorb water from the ground like a sponge. The presence of mica will affect the strength of the blocks, and they will eventually break up, it seems that after about five years.

The outer wall is most easily exposed to the natural environment, and the inner wall is better protected, but it is not immune.

For practical purposes, it is similar. Pyrite or pyrite (FeS2) is a common mineral found in sedimentary rocks and low-grade metamorphic rocks.

Reticulated cracks, fragments and plaster cracks appeared on the walls, which looked like slight sinking or "sediment" in the early stages. But over time, many houses have vertical cracks near the corners that extend from the ground to the roof.

The Statutory Document No. 288 of 1949 limits the total amount of impurities such as pyrite and mica in concrete blocks to 1%. The concrete block expert group consulted the National Bureau of Standards in its 2017 report to the government. The clear view of the authorities and the panel of experts is that the 1% limit still applies.

A 17% impurity/mica content in the area was found in the blocks of some affected houses in Co Donegal.

The Ministry of Housing stated that since 2013, according to EU regulations, “a set of uniform standards covers most construction products, including aggregates and concrete blocks”. This is called the Construction Products Code.

However, the department stated: “It should be pointed out that the main responsibility for proving that construction products meet the requirements of the construction product regulations lies with the product manufacturer.”

The Construction Industry Federation (CIF) provides insurance policies to homebuilders through HomeBond insurance services. These provide protection for issues such as "potential defects" and "structural issues". It is not clear how many builders of affected houses have adopted such policies. A question was asked to CIF on Monday and an answer is expected.

But according to activists, this is a controversial issue because many houses are one-off self-built houses, and the number of "manor houses" is considered to be very small.

not completely. The most recently reported number is 5,000 houses in Donegal and Mayo. But there are more reports of houses affected in Clare, Sligo and Northern Ireland. The final figure may be close to 10,000 houses.

Mica Action Group activists claim that building blocks from the same supplier have been used in public projects for many years. A spokeswoman expressed concern that these blocks might be in shops, schools or even hospitals.

The previous government announced a plan before the 2020 general election to support the affected households and pay 90% of the renovation costs. Recent reports citing government sources mentioned a figure of approximately 1 billion euros.

Tánaiste Leo Varadkar stated that the government is “eager to find a solution”. Housing Minister Darragh O'Brien stated that he and his department have been dealing with "the materials submitted by the action team we received five weeks ago, and we are liaising with other departments and agencies to find out how to best resolve the issues raised. some problems" .

After the homeowner received 100% of the cost of repairing the property, the pyrite problem was solved. The current defective concrete block subsidy program was launched last year and covers 90% of the reconstruction cost, but there are also obstacles.

The homeowner must pay testing, sampling and certification fees, up to a maximum of 5,000 euros. Does not include windows and kitchens, and does not include demolition and reconstruction planning and architect costs. The maintenance costs under the plan range from 50,000 euros for partial reconstruction to a maximum of 275,000 euros for demolition and complete reconstruction.

Many people affected claim that this is not enough. The program started accepting applications in June last year, and so far, fewer than 500 people in Donegal have started the process. Many dissatisfied people will express their feelings during the parade in Dublin on Tuesday.

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