Widening Closet Door - Lintel in Single Skin Party Wall

[PrettyFlyForADIYGuy]

I have just purchased a terraced house, which used to be a larger house, split into two some hundered years ago by a single skin of brick.

Some work I want to carry out is to soundproof the wall - the blue wall on the left, (most likely stud wall, rock wool, etc that's a separate thread covered many times), and widen the closet door to give full access to the closet (green dashed line), this will involve installing a new, longer lintel.

Before I delve into assessing the structure and doing the load calculations (The Eurocode has a nice section for this), I was wondering if somebody would please be able to explain requirements here from a building control/party wall agreement point of view? I assume both are needed.

I haven't stripped back any plaster yet, but the assumption is that either the existing lintel goes to half way through the party wall, or is continuous and forms the lintel of the neighbours mirrored closet. One of those scenarios is slightly easier to deal with than the other.

The closet contains the loft hatch, which I will also likely widen at the same time, to finish all the structural mods in this area before replastering.

Cheers for any thoughts and opinions.

 

[PrettyFlyForADIYGuy]

Bump, any help much appreciated.

 

[^woody^]

What is that wall above the door supporting?

You can leave the Eurocode book on the shelf.

 

[JohnD]

I don't understand your question.

You mention a brick party wall, and a studwork partition wall.

Which of them has the lintel?

Is the soundproofing part of your question?

The lintel appears to be reinforced concrete so will not be a hundred years old