Chimney breast removal

[Leccy]

I have a chimney I share with a neighbour. I've removed it and they're not happy. They did tell me I need a rsj, party wall agreement, building approval and an engineers report but it was cheap enough for me to just knock the chimney down. I've left the top bit so they can still use their fireplace. So not sure what they are moaning about. Is there a chance they can take me to court over this?

Yes, they can, you have not followed the party wall act procedure.
You could have damaged the structural integrity of the buildings, chimney breasts are a supporting structure (hence the need for an rsj).

Is this a reverse? No one would just knock it down.

Fraid so

We needed a concrete lintel as were only removing bottom half, a party wall agreement and engineering drawings to calculate the size of the lintel needed.

Absolutely you need all of the above. I suggest you speak to a structural engineer

You've left yourself in a vulnerable position without the agreement - previous cases suggest that if they accuse you of damaging their property, it's entirely on you to prove that you didn't. Secondly, leaving the top part of the chimney stack unsupported is not a good idea. Google 'chimney breast removal eccentric loading'. Assuming that it's your property, you're also going to cause yourself unnecessary issues if you ever want to sell - I'd think that missing Building Control documents relating to structural works is a definite red flag for most buyers... As with previous posters, you need to speak to an engineer and get it signed off. They charge a fair bit, but they also stop your house from falling down. (Also as above, is this a reverse?).

You will have left the top bit unstable. If you were my neighbour I would be extremely worried, and if you failed to remedy the situation immediately I would be taking you to court and asking for costs as well. This could really cost you.

You need building regulations approval to partially take down a chimney due to the structural issues involved - without it you are breaking the law and can be fined by the council and forced to rectify it.
You also need party wall agreement with your neighbour as this is also a legal requirement but they can only chase in civil not criminal court for this and it's up to your neighbour to chase (not that I would recommend this and I would side with the neighbours rights on this one) - this legislation is there to protect you from being sued and then from having to sue you!

So yes the neighbour can take you to court & the judge is likely to side with them and also the council can & will take you to court.

I don't really believe this is real as written. No one would just go and remove part of a chimney as described in the op.

Unfortunately people do do this. They don't tend to brag about it on mumsnet afterwards though.

You just knocked it down without inserting any kind of steel support for the wall behind it or the ceiling above??? You need a structural engineer round asap to check it's safe, then you need to hope you can sort this out amicably with your neighbours, as you're in breach of Building Regulations and you've totally ignored the Party Wall Act. So yes, they can absolutely sue you if you've left their house unsafe!

This HAS to be a reverse, surely?

Unfortunately people do do this and yes they are stupid enough to brag about it usually because professionals are so expensive and it's really easy to do it yourself 🙄
I am a construction professional so probably see more than my fair share though (&the aftermath) and I hope that the OP isn't really so stupid, although if it is a reverse it means her neighbour is.