Neighbours dormer loft over party line

[Jn46]

I live in a mid terrace and we did a dormer loft conversion 6 years ago. Kept within our side of party wall, so furthest extension is side of roof above soffits that hits the mid point. Flashing obviously goes over the ridge that makes up the party wall. I estimate our tiled dormer side wall is 15cm within the party wall line.

Neighbour is doing his loft and plans are to build up to party line. Builder wants to encroach over the line and join the walls.
No mention of this in the party wall agreement we signed.

Naturally I don't want them encroaching over the boundary, but would it be prudent to allow it in order to preserve my dormers integrity in the future, ie less chance of leaks etc? Might be looking to move house so don't want issues down the line.

Thanks.

 

[motorbiking]

What are they offering you in return?

Its probably better not to allow the encroachment. I suspect its because he can't easily finish his work to a high standard and may well tell his client to set back as you did, if you don't allow.

 

[Stivino]

I would allow it. It’s almost you going smaller is allowing him to go bigger.
They should keep all works on their side, it will be simpler.

 

[Tigercubrider]

would it be possible for them to carry the party wall upwards and build a shared roof?
if your Dormer isn't brand new it might be a benefit to you?
I am not a builder or lawyer

 

[motorbiking]

if you ever want to sell your property, you will need to disclose the encroachment to any potential buyers so that they can consider the issue as part of their purchasing decision.

 

[Jn46]

Thanks all. Went around and spoke to the builder direct this morning. The architect had essentially got it wrong, thinking our dormer was at the party wall line, not set back, hence the neighbour then asking about walls being joined (he is a bit clueless about anything building related). The neighbours will stay in their boundary, but batton and tiles will extend to join on the face, and roofs butted up and sealed. Most sensible option for both from a weather proofing perspective and closing off an inaccessible gap. I've asked the builder to take photos for me of the work so I have them stored for any necessary disclosure if it gets raised during a future sale.

Definately a headache though when it comes to mid terrace.

Unfortunately for the neighbour his quote has recently gone up £9k.