Big cracks! Who do I ask for help?

[Goodwordguide]

Moved into an old house about 6 months ago - it's200+ years with a mid Victorian extension. We had a full survey and a SE report to check for subsidence between the house and extension, which said that there was historic settlement but no evidence of subsidence. A previous SE report in 2007 (by the previous owners) said the same thing.

Anyway, just back from holidays and have noticed large internal cracks in the plaster running from ceiling to floor, both upstairs and downstairs, exactly where the extension joins the house. They are not hairline (I can fit my fingernail in them) and must have happened quite suddenly otherwise we would have noticed them before. Any ideas as to why they've suddenly happened and who do we ask to check them - a SE or a bullder/plasterer? I think the hall was repainted/replastered fairly recently before it was sold. Could it be the plaster drying out? clutching at straws

Slightly panicking that the extensionis about to fall away from my house...

Hot weather drying out the plaster could be it.

Also extension might not be keyed in so there could be a gap between original house and extension running the length of the house. Is it rendered externally? This is the case with our house. We have a gap about 2 cm running up the outside (hidden by render) and inside (hodden by plaster) of the house and the extension is joined by the roof. Looks scary but not moved anywhere in te last 150 years so not that bothered.

Have you checked if there are cracks outside?

Yes, nothing outside in the brick work.

Possibly one in the rendering outside where the extension drops a level (internal steps).

They are so sudden, I'm hoping that's a good sign, given the extension has been there 150 years+?

Does anyone know who's the best person to check this out ie, a plasterer or an SE or a specialist brickwork person? Thanks

Structural engineer but they tend to be slow to react - we've had similar - after two surveys when we bought now need to underpin! Expensive and an upheaval.

might get your insurance to send someone?

Is it usual to speak insurance people first? I'm dreading the thought of underpinning...

Not sure who would be best depends what it turns out to be.

It could just be where the old and new (100 year old new) plaster meet and has been filled over the year, reappearing because of the hot weather. That would just be a plasterer.

It could also be a reflective crack as there is actually a gap in the brick work (expansion gap) under it that has been plastered over. We had this and it was a structural engineer who suggested this was what it might be.

It could be something else entirely. I'd go for a structural engineer myself but they will be limited by what they can see.

How recently was it plastered? Might just be the new plaster drying out and shrinking a little where it joins the old? The cracks may not get any bigger and may not be anything to worry about. I'd just keep an eye on it and see how it goes. If no further widening of the crack I'd just leave it ( and paint over it).

Thanks everyone. I think the previous owners plastered and painted fairly recently so fingers crossed it's just the new plaster settling. I'm quite calm about this sort of thing but DH is panicking and it does look terrible - will get onto a SE

It sounds like the previous owners tried to cover up with the new plasterwork. I would call in a SE as soon as possible.