Fretting terracotta roof tiles

Why are my roof tiles turning to powder and what is this called?

A fairly common problem with terracotta roof tiles in Sydney is called ‘fretting’.

Fretting on a terracotta roof tile has various causes and salt is one common culprit. However, it is quite a difficult task to pin point the exact cause of the fretting. Some particular brand and production run of roof tiles seem to suffer a lot more than others. Some very old terracotta roof tiles do not fret – yet younger tiles do. Some terracotta roofs near the sea suffer bad fretting, while others fair quite well.

… And the problem is that most of the fretting problems occur under the lap of the roof tiles – so it is not immediately obvious where the problem tiles are. Each tile has to be inspected by lifting up the neighbouring tiles.

For roofs with no sarking, it is usually easier to inspect for fretting from the roof cavity – because the terracotta colour powder of the fault will fall onto the surface of the ceiling and the roof battens. This layer of dust is easy to spot. With sarked roofs, it is a bit more difficult.

A short term solution is to replace the tiles that are badly fretting. But fretting is a bit like cancer. It can be quite wide spread and you should consider a new roof if there is substantial fretting of your terracotta roof tiles.

… Another cause of fretting terracotta roof tiles is salt or chlorinated water on the roof. How does it get up there?

Swimming pool heating elements.

These rubber tubes can spring a leak from time to time and if the home owner is unaware of the leak, bad fretting will happen.

Just like on the video below:

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How the mostly roof tiles are fretting….! Video is showing the worst conditions of the tiles.

9 years ago

Hi there,

I have fretting terracotta roof tiles problem on my roof at 35 Shepherd street, Ashfield 2131. If I can buy some second hand tiles, could you give me a quote?

Many thanks,

9 years ago
Reply to  Jason


I will pop around to take a look at your roof first.

1 year ago

Dear mr Yuen

I have spotted a number of tiles experiencing fretting inside the roof by ripping the sarking. I have applied silicone to damaged tiles in the hope that it will delay the spread. Would you say its a quick fix based on your experience or its it that it will only delay the process of fretting. I dont even know if other areas of the roof is affected due to sarking underneath. Thank you hasan