Dormer and Party Wall

2 Jul 2020
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United Kingdom
Hi I live in a terraced 100 year old Victorian house and neighbour wants to build a l shaped dormer at the rear. My property shares the party wall where the main conversion part will be built (so not the small part of the dormer that the other neighbour will see.)and they will also cut into the main roof.
1. Can the neighrours wall be built wholly on to the party wall or must it stop at the centre of the PW?
2. If the builders require access to my property other than to take photos prior to the work what will it be for? I see that I may have to give access which is fine but why would they need to do any work my side?
3. In order to insert the beams into the party wall do they need access to my property to complete this work?
4. Finally can they build anything that will extend further out than the existing back main walls?
The image is similar to what will be built my house is the one on YOUR left as you look at pic.
Thanks in advanced


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1. No part of their proposal (wall and eaves) should oversail the boundary unless they have neighbours consent to do so. If they’re having to go down the formal Planning route, they should serve notice on you should there be any part that oversails. There isn’t however this ‘ownership’ section with LDC applications if they’re going down the PD route.

2. They may request access to finish off that side of the dormer cheek. It would also be in your interest to take and document photos before, during and post building works.

3. They would not need access to your property to insert the beams as these can be broken out and inserted into the party wall from the builders’ owners side.

4. I’m not really sure what you mean, but they should only build out to what they have received Planning approval for, albeit a LDC or formal Planning application.

Btw, make sure there’s a Party Wall Agreement in place before they start, usually two months prior.
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1. Yes, they can raise the party wall using their rights under the PW Act, and build across the boundary

2,3. Again, under the PW Act the builders can access your property to carry out works "pursuant to the Act", and this wont be just a request, it's a right.

4. Yes they can build out past a wall if that's the permission they have.
Thanks both for response
i have conflicting advise on point 1 though - i did not make the situation clearer. there is no Planning permission it is done under permitted development so only a Party wall agreement will be in place - although the building neighbour is stalling with showing me the plans and the build is due to happen soon.
I understand they will need to raise the Party wall but surprised the can do so past the boundary.
point 4 - i take it then that they cannot build past the external wall with no Planning Permission as it is a load bearing wall or original wall?
thanks again
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As Woody confirmed they do have the right to raise the full thickness of the party wall subject to serving the necessary notices and following the relevant procedures. So why not turn the situation to your advantage.

What I sometimes suggest to clients to get awkward neighbours on board where they want to build a new or raise an existing party wall is to agree to permanently defer the neighbour's contribution to the cost of building the wall. That way you get to use the new raised party wall at a later date to build your own loft conversion and you don't have to pay for half the cost of building the wall. Just make sure the wall is designed so that it can be used as a separating/party wall, is fully weatherproof whilst it is an external wall and you can build up to it easily (so no roof overhang on your side of the wall unless it can be easily removed/modified)

Obviously if you have no intention of ever building a loft conversion or are unlikely to sell so no chance a new owner might like the benefit of a free wall then it is of no benefit to you, but the neighbour could probably build the wall anyway and the only people to walk away happy are the party wall surveyors with their pockets stuffed with your neighbour's cash.
Thanks Wessex, and what are you views on the neighbour (item 4) extending backwards at the same time ie knocking down the back wall and moving it to towards the garden to make the proposed dormer bigger, i hope this makes sense. There is no planning permission involved.
And sorry to labour the point, so they can raise the entire Party Wall or thicken it etc - fine.
Looking at the red line in this image which represents the new wall of the Dormer can that be built over the boundary line or must it stop at the boundary line? I have not seen that anywhere from images online, the wall of the Dormer never goes over the boundary line


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