How to Tell If a House Has Mica: Signs to Check Before You Bid

You cannot confirm mica from the street, but a viewing can tell you whether to ask harder questions. Here is what to look for, what the signs can and cannot prove, and what to do before you bid.

Look at the external walls first. Mica-affected blocks tend to show as cracking in the render, often a map-like pattern or cracks that widen over time, and in serious cases as crumbling or bulging wall sections. Inside, check the corners of rooms and the walls behind furniture for new or growing cracks.

• Cracks that are growing. Ask the seller whether the cracks have been there long, and whether they have been repaired or painted over.
• Fresh render or paint on one wall. It may be routine maintenance, so ask what was done and why.
• Damp patches on cracked walls. Water getting in through cracks is part of how the damage progresses.

No. Settlement and other ordinary causes also crack walls, and a house with defective blocks can look fine for years. Treat cracking as a prompt to investigate, not as a verdict either way. The mica risk check shows whether an address sits in an area covered by the State schemes, which tells you how seriously to take the signs.

Confirming defective blocks in a particular building needs testing and assessment to I.S. 465, the national standard, by a competent professional. Ask the seller whether an assessment exists, whether a grant application has been made, and whether any remediation has been done. Put the same questions to your solicitor, and ask your surveyor what they can and cannot say about the blocks.

Pyrite is a separate problem, in the hardcore under the floor, and it has its own scheme. The Pyrite Remediation Scheme closes to applications on 30 November 2026, according to the Pyrite Resolution Board. Our pyrite deadline guide covers what that means for owners and buyers.