Help crack external wall of extension

Hi Im looking at a house there's couple things that I'm looking at on it to do if I proceed, I mentioned previously in a post there's some scaffolding poles up but iv also found this long crack on the extension wall in another location with some sort of glue or what feels like silicone on it... Iv attached couple of images Does anyone know what this could be and how I can fix it or cost. Its an older house and on a hill so was thinking subsidence or something appreciate any advice, Thank you

Deedandee, good evening

At first glance the cracking appears to affect the smooth cement render, where water has managed to get behind the render and during the freeze / thaw cycle the render has de-bonded.

Are there any indications of internal cracking in the same [general] area?

Any chance of an image of the area of damage from a bit further back?

Do you know what soil the flat is built on? are there any trees within about 10 / 20. m?

Ken

Thanks for the info, Sorry this is my only picture at the moment close at that angle but iv attached one where I was photographing the scaffolding it's the side wall you can just see it if that helps.. it's a house with a double extention then a single extention on to that it's on the single part. From here there is a balcony/terrace which has steps that go down to a lower garden no trees.. I did notice some work on a guttering that's running off the conservertry part that runs towards there so water damage might make sense. Inside seems fine.. Thank you for all your help. Dee

I'd recommend using an angle grinder to make the crack slightly wider, then gun in some Toupret Fibacryl. It is a caulk that is reinforced with fibres. Given that it is water based, it will shrink back slightly. After a day or two, then fill with Toupret Touprelith F.

Materials will cost about £20 excluding sandpaper and paints. You will have a lot of materials left over though. Hopefully you will be able to use them elsewhere.