Kitchen side-return extension - what height I am allowed to build the boundary wall up to

[Johnbuoy]

We live in an Edwardian house in London (Ealing) and we are planning to extend our single story kitchen into the side return up to the boundary with our neighbour.
I haven't discussed it with him yet but was wondering what height I am allowed to build the boundary wall up to without a party wall agreement?
I've had a couple of quotes and the first builder seemed to suggest we could only build up to 2 metres unless the neighbour allows us to go higher.
The second builder suggested that we'd be able to build to a height of 3.5 metres. (We'd actually only need to go to 3 metres to match the existing kitchen.)
Who is correct?

[Humptynumpty02]

Surely if you are building it up even 1 cm you need to use a Section 2 party wall notice?

[PanannyPanoo]

Ring your planning department. They are very helpful. It is my understanding that you have to get a party wall agreement for any building on or near the boundary.

[Humptynumpty02]

That's not correct, there are certain requirements to issue a party wall agreement, eg you are building foundations lower than your neighbours and the works are within 3m. There are also many scenarios where you don't need to issue a party wall notice. Also party wall matters are not a planning issue so the local planning department won't care one bit.

You're better off speaking to your architect, or a party wall surveyor. Any decent party wall surveyor will give you 30 mins 'free' time so you should be able to ark yourself with the facts pretty easily.

[Sarahsea1]

It varies in London boroughs and whether your neighbour has extended. For instance, under planning permission in LBHF it’s 2metres unless your neighbour has also done a side return then it’s 3. There’s also the permitted development rule but this may not give you the length for a side return. Wandsworth has different rules. Upshot is, speak to your local planning officer who will offer short consultations for free and prepare for a party wall award - assuming you’re a terrace. As others have said, party wall notice is entirely separate from planning, as our building regs which you’ll also need to follow.