Is this crack worrying? Subsidence?

[Happygoluccy]

Purchasing a period flat and these cracks are on the outside of the building. Is this worrying? Rendering looks in bad condition anyway, but does this look structural? Surveyor who did the report was pretty vague which isn’t helpful and is not willing to provide any further advice, ignoring calls etc. So I either pay double for a structural survey or hope it’s nothing serious! Some photos below.

I'm no structural engineer but yup, looks concerning to me.

I'm not a structural engineer either, but there is no way I's buy that property without a structural survey. I know it's more money, but it will give you the information to make the right decision for you.

What do the walls look like on the interior?

I think you're right to be concerned from the initial appearances, but to get a better idea of the situation I suspect a lot of the render is going to need to be removed, and I suspect the vendor would be less than thrilled at the prospect.

Have they had any work done that could have made the building resettle slightly - an extension or new windows? The first picture would worry me because it looks like someone's tried to plaster over it in the past, possibly to hide it.

DH is a structural engineer. I would not get a structural survey from a surveyor. They will sit on the fence! I would pay an engineer to look at it. Someone with experience of this type of issue. If it needs repair the owner will have to do it on their insurance.

I’d be wanting a structural survey from someone who’s got experience with subsidence and other structural issues.

If it is something serious, better to pay out for a proper thorough survey and find out now.

internally, there are cracks in the wall under the windowsills, I think in all rooms except the bathroom. The cracks (horizontal) are aren’t massively wide, so maybe that’s a good thing.

I'm no expert but it looks serious and not something I'd buy.

Looks concerning. Lots of subsidence about at the moment due to drought conditions, especially in clay soil areas when the ground shrinks due to lack of moisture. Are you in London? Or another area of clay soil? I’m not a surveyor or engineer but do work with property and a rule of thumb used to be that if you can get a finger into the crack then it’s definitely a major structural issue.

Also, once conditions become wetter, clay soils will expand and “heave” will occur - subsidence in reverse when the ground rapidly expands with moisture and creates lifting movement in buildings. It’s likely that the expansion/contraction movement cycle isn’t finished yet and any cracks will get worse.

Where are those external cracks relative to the building? My house has something similar and also cracks inside under the windowsill. It isn't subsidence in my case but lack of damp course and water ingress. However I am absolutely not qualified to offer you advice on your purchase. Structural engineer sounds like a good call, but cracks don't always spell doom.

No, cracks are not always worrying and could be damp behind the render.Although the origin of any damp needs investigation. The straight crack could be where an extension joins an original building or just a bit of drying out. It doesn’t look serious.

@MadeInChorley it’s Kent so not sure if that’s a clay soil area. I’m going to arrange another visit to the property so I can see how wide the crack is for myself. Hoping the picture is worse than it is in person.

@Goawayangryman the external cracks are kind of everywhere. But most worrying ones are ground-floor and lower ground floor. Glad that yours didn’t end up being subsidence in the end!

Whilst I am not an expert I have been told in the past that the worst sort of cracks are those that follow the lines of the brick mortar so zig zag sorts of cracks. The render has probably 'blown' and needs redoing. Ours is being redone at the moment as our West elevation is riddled with cracks like those shown. But it's not structural although the damp is getting in. It's very expensive to do and a proper ball ache as you have to pay for everything to be temporarily removed form the walls like electricity bits, plumbing, sky, alarm etc etc.its eye watering. Avoid like the plague!

Cracks are appearing in walls in most houses in the area I live due to the hot weather.

There are heave cracks where too much moisture pushes the walls outwards and subsidence where the walls collapse downwards. They produce differing patterns of cracks.

You need advice if this is purely a render issue or a wall and foundation issue. A good look at the building from an engineer would tell you if it’s old cracks due to historic settlement or damp or something worse. If it’s worse, then talk to the vendor.