Mica in Donegal, Mayo, Clare, Limerick and Sligo, what is happening and how can 2020 Architects help

If you live in any of these counties in Ireland, unfortunately you don’t need an explanation for the word “mica”. For those who don’t, it can mean cracking render, crumbling blockwork, doors and windows that won’t close, and a constant worry about the building you call home.

2020 Architects are currently working on several replacement dwellings for ‘Mica homes’ in Donegal. We are also fortunate enough to design the family homes of the owners of Cross Concrete, one of the largest precast concrete floor companies in the northwest of Ireland, a company who were totally clean in terms of mica but who have been unfortunately affected personally by mica blocks in their family homes like so many others.

We wanted to pull together all the information and outline how the Enhanced Defective Concrete Blocks (DCB) Grant Scheme works in 2025, the information that everyone who is affected by mica should have and how 2020 Architects can help you and also information we are receiving from clients affected and already in the process of getting redress.

What is the mica/defective blocks problem?

Mica or Muscovite is a naturally occurring mineral found in rocks but unfortunately when too much of it is in concrete mix, the concrete is significantly weakened and the mineral will also absorb water and expand, causing widespread cracking and structural damage over time. Ireland’s technical standard I.S. 465:2018 defines how suspected homes are assessed, tested and categorised for remediation. It is the benchmark engineers use to confirm damage and recommend the right fix.

Who can apply for support?

The Government’s Enhanced DCB Grant Scheme supports affected homeowners in the five designated counties where homes were damaged using defective concrete blocks. You can apply if the dwelling is your principal private residence, or a rental property that was registered with the RTB on or before 1 November 2021. Applications are made through your local authority.

What compensation is available?

The scheme pays up to 100% of approved remediation costs (or 100% of vouched costs, whichever is lower) subject to an overall cap. From 22 October 2024, the cap was increased by 10% to €462,000 (previously €420,000). Per-square-metre grant rates were also uplifted by ~7–9% to reflect recent construction inflation. In May/June 2025 the Department confirmed these higher rates and outlined plans for retrospective application via legislation.

mica in concrete

The five remediation options

Depending on your engineer’s assessment under I.S. 465, the Housing Agency will determine one of these five routes:

  • Option 1: Demolish & rebuild the entire home
  • Option 2: Rebuild both leaves of external walls to foundation
  • Option 3: Rebuild both leaves to the top of rising walls
  • Option 4: Rebuild outer leaf only to the top of rising walls
  • Option 5: Rebuild outer leaf of affected walls only

However, as Mica has been found in the foundation blocks of the affected homes, rebuilding the visible walls has limited effect and so Options 2-5 are not ones that we would recommend. There is little point removing the visible issues when below ground the blocks that the house has been built on are also turning to powder. In our opinion the only option for anyone where Mica is found to be present is demolition unless there is definite proof that Mica isn’t present in the foundations.

The problem with this conclusion is that there is anecdotal evidence or at least a suggestion that applications for houses where Mica is apparent, but the damage isn’t severe, are being pushed to the back of the queue. This may be just a sensible use of resources as some of the worst cases are major health and safety concerns but the worry for house holders is that these minor damage cases won’t be deemed to be as important because of the lack of visual evidence.

There is also a suggestion that the final payments for houses are being held up which puts major financial strain on the homeowner as the contractor or sub-contractors need to be paid. It is worth bearing this in mind to ensure that you have enough money to finish the build or can access some form of bridging loan to ensure that payments can be made if the final grant payment is held up.

Ancillary supports

On top of construction costs, ancillary grants help with temporary accommodation and storage while works occur. Individual councils administer these and will confirm exact entitlements when approving your application.  If you are rebuilding under Option 1, you can also combine the DCB grant with SEAI grants to improve the energy efficiency of the new home and reduce your running costs.

How to apply 

  1. Start with an engineer: Commission a Building Condition Assessment to I.S. 465. You can find qualified engineers on the Engineers Ireland IS 465 register.
  2. Apply via your County Council: The council validates your file and liaises with the Housing Agency for the damage threshold, remediation option and grant amount. Applications and practical guidance are on the Donegal DCB hub and application portal.
  3. Approval & payments: If approved, the council will confirm your option, maximum grant and conditions, and invite you to claim ancillary supports if needed.

Common question we are asked.

Will the grant cover everything I need?
The DCB grant covers 100% of approved costs up to the €462,000 cap; unfortunately, due to the current costs of construction this figure is still often not replacing your home like for like. Even with the additional SEAI grants it is unlikely that you will get a like for like replacement and as such many people are considering a redesign both to achieve a house that matches how we live and also simplifies the build to get the most value for money.
Is full demolition always best?
Yes, in our professional opinion a full rebuild is the only way to ensure peace of mind. Mica is a problem when blocks get wet, as such any blocks that have mica in them below the DPC (damp proof course) will be an issue. All of these blocks are hidden from view and there are few ways to understand the extent of the problem. If in doubt the entire house should be replaced for health and safety concerns.
Can I improve the house while I’m at it?
Yes. People are using this as an opportunity to re-plan layouts, add light/space, and with the SEAI grants make the house more energy efficient. With the rising cost of construction, we would also suggest that with good design you can achieve a better house, that is designed for modern living and is lower cost to construct rather than just replacing like for like.

How 2020 Architects can help

  • I.S. 465-aware design & planning: We can coordinate with your engineer, so the chosen plan is designed correctly from the start.
  • Grant-friendly specifications and cost-efficient designs: We specify materials and details that align with the scheme and can design simple modern Irish homes that will reduce the construction costs and help the grant cover the full cost.
  • End-to-end support: From concept and planning to tendering and site inspections 2020 Architects offer a full architectural service.

Useful official links (Donegal homeowners)