Derry City & Strabane - Defective Blocks- Mica, Pyrite, & Pyrrhotite




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Defective Blocks- Mica, Pyrite, & Pyrrhotite


Mica, pyrite, and Pyrrhotite are minerals found in the ground and in rocks that are excavated from quarries and used in building blocks. These minerals cause defects in building blocks, which lead to cracks and other problems in buildings and homes constructed with the defective blocks.

These elements have been found in quarries in the North West and East of Ireland and it is possible that some properties in the Derry City and Strabane District Council area may be affected by them. 


Do You suspect that Your Property in the Derry & Strabane District has been affected by defective blocks?

Derry City and Strabane District Council are keen to hear from any property owners within the Derry and Strabane District Council area who suspect their residence/dwelling has been impacted by defective blocks including MICA , Pyrrhotite and Pyrite. We no longer require property owners to have evidence of this by an authorised defective blocks testing organisation or structural engineer.  

However, it is important to note that DCSDC can not carry out any form of defective blocks testing on any property within the city and district. We recommend property owners who wish to carry out testing to seek the advice of a Structural Engineer, in the first instance, and who would be best placed to advise further. 

We are carrying out a data collection exercise which will allow us to quantify how many homes / properties within the Derry and Strabane District maybe affected by defective blocks.

Please email: with the following details:

1.      Your Name

2.      Affected Property Address

3.      Contact Number

4.      Copy of Certified testing/documented evidence to prove your property has been impacted by MICA.