Any plasterers or experts who could tell me why these cracks have suddenly appeared?

[Wiifitmama]

I have attached two photos (I hope!). The close up shows the deepest crack and the other tries to give some idea of scale on wall.

It is a wall to a bedroom. It is NOT an external wall but the cracks seem to be radiating from the external wall where a window is.

It is a ground floor flat of an old victorian building. We had major works done a year ago. This particular bedroom was divided into two with a partition wall, but that wall is opposite to the one affected. The whole room was skimmed with plaster and redecorated.

It is my son's bedroom and he only mentioned the cracks today. He said they appeared about 3 or so weeks ago but suddenly seem much deeper. This coincides with the really hot weather (we are London) so could that be related?

It appears to be the plaster that is cracking. Not structural. Any thoughts?

The other side of the wall is actually the entry to the flat above. We do not have access so I can't see what is going on that side.

If anyone has any idea, I would be grateful!

Possibly just settling/slight movement

Yes, we have slight cracking elsewhere from settling. We are on London clay and it is an old building. But we have been here 8 years and this has never happened on this wall and has been quite sudden and quick. That is why I am worried. The deep crack is quite deep but only seems to be plaster.

We've noticed cracking in our house too (older property, built on clay). Having sought advice from people who know more than us (albeit not professionals), the general consensus is that it's weather-related and caused by the extremely hot summer we've had. As long as the cracks aren't too wide (I think if you can get a pound coin in, it's probably time for professional advice ), I don't think it's too worrying - just keep an eye on them.

Thanks. I did wonder if it was a combination of the extreme heat and newish plaster? Odd that it is only that wall Though.

With the caveat that I know virtually nothing about this, it wouldn't surprise me if new plaster takes some time to "settle".

With clay underneath it gets wet in the winter and dries out in the summer, but due to the heat this summer, the clay is very dry and settlement or even subsidence can happen. As clay gets wet it expands and as it dries it shrinks. I wouldn't worry if it's an old building because slight movement is normal particularly in these conditions. If it gets wider by 2 or 3 mm you might want to have a surveyor look at it to check everything is ok or you could contact your insurer. Your insurer will increase your premiums though.

I would ask if you can see what’s happening on the other side. It’s a reasonable request to your neighbour. It really depends if this is the plaster drying out or whether there is a structural problem causing subsidence to the actual wall. I doubt it’s the latter as it’s an internal wall but if it was you would see cracking on both sides.

Normally subsidence shows on the external walls by very obvious cracking. Can you see anything on the outside at all? If the cracks are just in the plaster and not the bricks, then it is probably just dried out olaster that can be repaired. Get a Structural Engineer to look at it if there is further cause fir concern. Don’t get insurance involved if there is no need and it’s just a repair.