What is a "hairline crack"?

Non-structural hairline cracking in plaster occurs mainly due to the curing and shrinkage process after application.

The NHBRC classifies cracks as follows:

1. Hairline cracks less than 0.25mm width are classified as negligible.

2. Fine internal cracks which can be treated during normal redecoration and that are rarely visible in external masonry - < 1mm as very slight.

3. Internal cracks easily filled -redecoration required - and recurrent cracks which can be masked with suitable linings -< 5mm as slight.

» Back