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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

AIBU with my neighbour about our boundary

156 replies

ThisPinkCrow · 17/03/2025 20:26

Hi all,

We have just bought a house in London and are new homeowners. My adjacent neighbour has also bought their house at the same time as me and has begun doing works to it.

My neighbour wants to install EWI and a French drain along their main wall that is only accessible via my side access. I am seeking advice about what people would do in my position because it's not clear to me. Strangely, I can't find any examples of my situation on the internet. I would have thought this is not an uncommon thing. I want someone to tell me YABU/YANBU or if I'm missing anything really obvious here.... thank you to anyone who reads this.

The neighbours house is extended at the rear on the first and ground floor while mine is not extended at all. Both of our houses have damp issues on the ground floor. The neighbours wall is solid up to point of their extension, the extension has a cavity wall above and below. Among other things such as a French drain, as part of a multi-pronged effort to tackle this damp, my neighbour wants to install exterior wall insulation of ~ 10 cm thickness on all the sides of their house. I want to state at the offset I want my neighbours to be able to put insulation on and improve their wall. At the same time, I don't want to agree without being fully informed and regret it later.

The side wall of the main living area of their house borders the full length of my side access. My side access is only accessible to me by my gate. My side access leads straight to my garage at the very back of my garden. Their main wall is stepped out ~ 10cm in places for the two chimney breasts, before it recesses back into the main wall. At the top their roof soffits go another ~10cm beyond the chimneys, and then the roof gutters another ~ 10cm, so overall the furthest part of their structure projects give or take ~30cm from the main rendered wall.

The titles of our properties indicate an approximate straight line boundary along the wall, which then joins the garden fences and the driveway hedge/brick.

The neighbour suggested initially that the boundary follows a straight parallel line from the chimney breasts, so the gap sandwiched between their chimney breasts is their land, which means they can insulate and they just need permission for access and nothing more.

My view was that logically the boundary between our plots would follow exactly the shape of the main fixed structure which is the foundational wall, so along the main recessed wall, then following chimney breast 1, back to the main wall, following chimney breast 2, back to the main wall until it meets the garden fence which aligns with the main recessed wall exactly.

I thought that this is the boundary because the corners of their main wall precisely align with the edges of fences / connecting boundary features that separate our properties at the front drive and at the back garden. This is also the case for other properties with chimneyed walls along the same road. There is also a side access garage extension on the same road which has been built right up to the other house's wall since forever, including fully wrapping around the chimney breasts of their neighbours wall. Not that I would dream of doing this or that it would be approved these days but it seems indicative of where a technical boundary is. There is also a more recent side extension on the same road that looks like it stops not far from the adjacent properties roof structure, but my assumption there is that this was stopping some distance short of the main boundary which is the wall.

The insulation they proposed to put on would not go further than their current chimney breast depth, so in effect their wall would become straight as the parts of the main wall would be brought outwards, with insulation, to the chimney breasts which would be re-rendered but uninsulated (insulated internally) - so that the minimum width of my current side access (2.3 metres), which is set by the protrusion of the chimney breasts, is unchanged. The total area here that would be used by the insulation along this small strip that goes along their wall is only about 1.2 metres squared (12 metres length of their wall x 0.1 metres width).

I said OK to most of this, if that strip is technically my land then they can have that. Additionally I said that they can put the drain adjacent to their newly insulated wall provided that we agree the drain isn't changing the boundary, which we would both then agree follows the shape of their now insulated main wall.

The one material amendment I suggested is a ~ 2m length gap of uninsulated render at the end of their rear extension on the ground floor (which is ahead of the end of my unextended house) - because their extension has a cavity wall and the damp issues are not significant there and something can be done internally. If I wanted to do a rear extension and extend this rear extension out to the side, I would prefer to have all the space I can get even if it's just 10cm. I felt like this was a reasonable compromise where we both got enough of what we wanted - they got 90% of the insulation and the drain, I did not have the most usable width removed from my side access if I wanted to bring vehicles through. Then we would do a normal boundary agreement between ourselves and register this with HMLR which is very cheap and easy to do.

After hearing this the neighbour has paid a lot of money for a surveyor to do a determined boundary report to clarify the boundary. I said I would accept the outcome if the report explained why my thinking was incorrect, then they would seek to register the determined boundary with HMLR.

The report caveats that this is the surveyors opinion because they do not have the original plans, but the surveyor says that it's most logical that the boundary at the wall goes up to the end of my neighbours roof gutters. So my thinking is wrong, and the neighbours thinking that their boundary extends from their chimney breasts in a straight line is also wrong.

My reading of this is that all the land projected downwards from the edge of the neighbours roof gutter is theirs. Basically it's saying they own ~ 25-30 cm of my side access on the ground and all the airspace above it. The report doesn't references other houses locally or on the street, other than to say they also have projecting roof gutters, nor does it explain how the current garden and drive would be visibly offset from the roof edge were this the true boundary, it more seems to assert the conclusion based on the surveyor's experience.

If this is the true boundary then the neighbour does not need my permission to do improvement works to their wall (the insulation and the drains come within this 30 cm strip) they only need permission for access, permission which I would obviously grant if I believed the surveyor is right.

My view was that the gutters and soffits at the top could be classed as a minor trespass at most, or in effect they may be allowed to overhang the boundary because it's not bothering anyone. I was never remotely concerned or bothered about this overhang until I read their surveyor's report. This was not mentioned when I was purchasing my house but I don't blame anyone for that. I don't care about the overhang as long as the downpipes, which come down adjacent to their chimney breasts along their wall, don't discharge on my side and they do not, it doesn't cause any harm to me and if they wanted to maintain that they'd always be given access immediately.

If I accept the edge of the gutters as the boundary, this means my side access can be narrowed another 20cm by the present neighbours or (more likely) future owners if they ever choose to do so and I have no say in the matter. If I also choose to put minimal 10 cm insulation on my wall on my side of the side access (which is currently uninsulated just like the neighbours is), then in the worst scenario the minimum width along my side access at the pinch point could be reduced to less than 2 metres, and I can't really accept that if I want the option to bring vehicles through in future.

I am not really sure what happens next at this point. I just read the report and I've messaged my neighbour to tell them I don't feel like the outcomes are well explained and that if they believe the outcome, that they own ~30cm of pathway in what I perceive to be my side access, and seek to register this boundary I would have to dispute it reluctantly. I've also asked them to forward my details to the surveyor to get in touch with me so they can be better explained to me in case I'm just not getting it.

I'm still on good terms with the neighbour from my perspective, like I'm trying to be difficult, and we're still communicating with each other without any problem, and I don't have any problem with them either. but obviously this is starting to seem like it's about to go off the rails.

So.... AIBU to my neighbour here? Am I just crazy and this is what the boundary really is? If the situation was reversed and I just bought their house and they had bought mine, I do not believe I would assume that I owned part of their side access because my house's roof soffits and gutters slightly overhanged onto their side.

However, if I wanted to insulate my side wall and add a drain to reduce damp, I think I would be completely normal to want those changes and to hope that the neighbour wants to try to work with me to allow them, and to arrive at some compromise which isn't perfect but works well enough, while maintaining an agreement about the existing boundary.... that's what I've tried to do. I've not said no to anything that impacts their ability to tackle their main damp problem that they've asked of me until this point.

But if they want me to accept a determined boundary is somewhere massively different than where I thought it was in order, and then register it, in order to then tackle their damp then I'm not sure how that doesn't lead to solicitors and lots of money going up in flames. I wouldn't be bothered at all if the side access was another 20 - 30cm wider at its narrowest either but it's not and vehicles seem to only get bigger with time, equally I would be worried about what accepting this proposed boundary would do to my house value.

Thank you to anyone who made it to the end of this long post.. I tried to shorten it but it's still lengthy.

OP posts:
Thread gallery
11
ThisPinkCrow · 17/03/2025 22:16

Seeline · 17/03/2025 22:15

How old are the properties?

1930s, both probate properties from their very first owners.

OP posts:
ThisPinkCrow · 17/03/2025 22:19

stayathomegardener · 17/03/2025 22:07

A 10cm ransom strip could be worth 100's of thousands in the right circumstances.

I know you aren't looking to profit or made things difficult but honestly your neighbours are being CF's.

For reference this is London and in an area where detached houses are very uncommon and the few that exist are typically not very big or wide.

I am lucky on my side because I have my own strip on the other side too, my neighbour does not.

What is a CF? Oh, I got it after I thought about it for a second. Well I don't have that impression yet. Perhaps I'm naive about this as I am a first time homeowner, they are not.

OP posts:
parietal · 17/03/2025 22:21

beautiful diagram.

i'm not sure anyone on here can give you a perfect answer, but do definitely consult the professionals before you agree to anything.

allthemiddlechildrenoftheworld · 17/03/2025 22:22

@ThisPinkCrow their house wall is actually the boundary?? is that quite common around your area?? I dont think I would be giving up any of my ground to neighbour. would she give up some of her ground for her other neighbour to do the same as she is doing?? I doubt it!! she is trying to pull a fast one! also, any water soakaway would land on your ground!!

BellaVita · 17/03/2025 22:23

Nowvoyager99 · 17/03/2025 20:27

All that text and no fucking diagram!

Are you new?

😂

Hysterectomynext · 17/03/2025 22:28

Fookin heck. I always make an effort to read full posts but that’s too long

SinnerBoy · 17/03/2025 22:29

ThisPinkCrow · 17/03/2025 21:28

Ok, sorry all. I hope the images below help. It doesn't discuss the details of the context that led to this (putting insulation on their wall and a drain adjacent the wall, both of which I have co-operated and proposed a solution for), this is in the main post, but it at least shows what we both think the boundaries are. At this point it is just this determined boundary report which I think is unreasonable, at the same time.. I am not a surveyor, so I do question my own opinion, but the surveyor doesn't really explain why it is like this and more asserts it based on their experience.

If the diagrams do not add clarity let me know and I will be clearer.

Basically, am I being unreasonable to think the boundary is what I think it is and finding the surveyor's suggestion of it to be inaccurate?

I have not read the other posts but will get around to it shortly.. thank you all.

Edited

Blimey, for a first time poster, you've just won Best Diagram Evah on Mumsnet!

Get your own party wall surveyor, they have to pay. I think (could be entirely wrong legally, but not, I think, morally) that their protruding chimney doesn't give them rights on your side.

ThisPinkCrow · 17/03/2025 22:30

allthemiddlechildrenoftheworld · 17/03/2025 22:22

@ThisPinkCrow their house wall is actually the boundary?? is that quite common around your area?? I dont think I would be giving up any of my ground to neighbour. would she give up some of her ground for her other neighbour to do the same as she is doing?? I doubt it!! she is trying to pull a fast one! also, any water soakaway would land on your ground!!

Edited

I am assuming it is the most rational boundary because it aligns best with the diagram on the title, and also because it just seemed reasonable to me to think that it was because the wall aligns with other boundary features, hedges and fences. If the boundary was actually up to the roof gutters and I knew that ahead of time, it's possible I would not have bought the house!

At the core of it is a pretty basic question I guess, do you own everything below the distance of any objects that protrude from your walls, or do you not. Or inversely, if I have a tree whose roots go past the garden fence, does that mean I own a part of the neighbours garden.. I shouldn't think so.

I did ask if the neighbour would just say yes without asking questions at the beginning, and they said yes. They have a similar neighbour and wall with chimney breasts on their side. They think it's not a big deal, the idea that I or future owners might put a car through the side access is not something that interest them, they see the garage as for storage. Either way, the insulation they want to put on does not impact these issues since I did the measurements, and I accounted for my potentially adding 10cm insulation on my side in the future. Obviously a side extension could also be more limited in its width, but that's only if they went past the chimney breasts, which they are not doing. In my view they are being very reasonable with the amount of insulation they want to add.

OP posts:
Agapornis · 17/03/2025 22:31

Excellent diagram. Stick around for a while longer OP, you'll see some funnier (worse) ones.

Are you in an old [Victorian/Edwardian] house? I know you said the level of damp proofing scam they buy isn't your problem, but there are a lot of dodgy scamming companies who will accidentally on purpose grab more land.

Old buildings need to breathe. Damp proofing doesn't work because the building materials used are not made to be impervious. Sometimes it's decades of layers of paving that causes the problem. For that you need to dig down so the soil is back to its original level. Sometimes there is a cement render that is rotting away. Using a shitty damp proofing company isn't a solution. For your own house, look at some of the resources that SPAB produces, and try to find someone who works with old houses.

You should definitely not give them that 30cm for free - it'll only be the start of them taking the piss. Stick to the Land Registry for now. Get your own legal advice.

Nextdoor55 · 17/03/2025 22:34

So this surveyor has said that the boundary doesn't fit what neighbour says or what you say? If you aren't happy you could get your own advice? are you mortgaged? the bank will want to know about this and may have their own opinion and advice.
I wouldn't be giving them anything under these circumstances.
You could try legalbeagles online legal advice, they might help?

ThisPinkCrow · 17/03/2025 22:36

Uploading an additional image I found that shows the actual structure with chimney breast in question. Ignore the scaffolding, they are doing separate repairs to the roof which obviously I have no issues with.

AIBU with my neighbour about our boundary
OP posts:
Mandoidi · 17/03/2025 22:38

DonutsWin · 17/03/2025 21:30

If you have a mortgage on the property, you have to involve your lender. You cannot cede something that you don’t completely own.

Whyyyyyyyyyyyyyyy did you quote the war and peace post for goodness sake

Icanttakethisanymore · 17/03/2025 22:38

You’ve really redeemed yourself with that diagram OP - 10/10. Unfortunately I don’t know the answer, but before that diagram I had no idea what the question was.

ThisPinkCrow · 17/03/2025 22:39

Nextdoor55 · 17/03/2025 22:34

So this surveyor has said that the boundary doesn't fit what neighbour says or what you say? If you aren't happy you could get your own advice? are you mortgaged? the bank will want to know about this and may have their own opinion and advice.
I wouldn't be giving them anything under these circumstances.
You could try legalbeagles online legal advice, they might help?

That's correct, the determined boundary is different from what both of us think and in a way that goes massively against me, but more importantly which to me does not make any sense... Even with this boundary, if people here are telling me that this is actually completely normal and I'm being unreasonable then you know I might be able to make it make sense. I'm in my own bubble here, I think I'm making sense but I haven't obtained my own surveying (except L3 when buying) or legal advice yet. Also, I don't know many people who own proper houses which is a bit strange maybe, but I don't have people to ask.

I have relied on my neighbour to talk with their solicitors and their suveyors. What I'm going to do at this point is follow the many suggestions given. Thank you for your suggestions.

OP posts:
allthemiddlechildrenoftheworld · 17/03/2025 22:41

@ThisPinkCrow if you intend in the future to bring vehicles through the area, the pipes are surely in danger of breaking! I am not sure I would allow this because I am pretty sure the surveyor is incorrect. Have they started the work already?? just wondering due to the scaffolding???????

allthemiddlechildrenoftheworld · 17/03/2025 22:46

@ThisPinkCrow found this!! boundary is the wall, not the eaves!

Here's a more detailed explanation:
Walls as Boundary Markers:
When a house is built right up against the boundary of the land, the boundary usually runs along the outer face of the external wall.

Nextdoor55 · 17/03/2025 22:47

ThisPinkCrow · 17/03/2025 22:39

That's correct, the determined boundary is different from what both of us think and in a way that goes massively against me, but more importantly which to me does not make any sense... Even with this boundary, if people here are telling me that this is actually completely normal and I'm being unreasonable then you know I might be able to make it make sense. I'm in my own bubble here, I think I'm making sense but I haven't obtained my own surveying (except L3 when buying) or legal advice yet. Also, I don't know many people who own proper houses which is a bit strange maybe, but I don't have people to ask.

I have relied on my neighbour to talk with their solicitors and their suveyors. What I'm going to do at this point is follow the many suggestions given. Thank you for your suggestions.

Edited

I don't think you are being unreasonable, it may be that people put yabu due to the lack of diagram! but you really aren't, its not right as you will need to be able to sell your property in the future, and you can challenge this, it might be awkward but you don't need to be agreeing to anything if you don't think it makes sense.

ThisPinkCrow · 17/03/2025 22:48

allthemiddlechildrenoftheworld · 17/03/2025 22:41

@ThisPinkCrow if you intend in the future to bring vehicles through the area, the pipes are surely in danger of breaking! I am not sure I would allow this because I am pretty sure the surveyor is incorrect. Have they started the work already?? just wondering due to the scaffolding???????

Edited

There are some drainage pipes and a few other weird things (I think they have a really old fireplace, there's like a big metal fan or something, not sure what it is, that sticks out of the chimney breast) that project from their wall further than the chimney breasts right now. The chimney breast is just part of the fixed structure. The neighbours, without my asking, said they would shift things around to make my actual usable width wider in any case - by getting rid of these other objects that protrude from the wall at the ground level.

The works above are for repairs to their roof, which is all I have consented to at this point. They do have access to my property at present, but we have an agreement that it is for repairs to their roof; I think they are reasonable people, I may not know them well but I trust my gut enough to say they are decent and will not go against that. I am not living at the property right now and I trust them enough to allow access for whatever they need to do, as long as we agree on it, and so far we have.

OP posts:
mineallmine · 17/03/2025 22:51

Hi OP, I didn't read your full post (too long for me at this hour of the evening, sorry)

Our side extension was built on our shared boundary with our neighbour. We were getting external insulation on our very cold 1940s house. We wouldn't even dream of asking them if we could externally insjlate our side extension wall on their side. We just insulated that wall internally.

It's completely out of the question that your neighbours should expect this of you. Let them insulate that wall internally. It's not your problem that it will make their room smaller.

It's so completely cheeky that your neighbour is trying to bulldoze you. Hold your boundaries with them, literally.

Melroses · 17/03/2025 22:52

Do you know when the extension was built? - there may be drawings with the local council that may help, along with the Land Registry maps.

Also, like others have mentioned, the Party Wall Act may be useful.

ThisPinkCrow · 17/03/2025 22:52

allthemiddlechildrenoftheworld · 17/03/2025 22:46

@ThisPinkCrow found this!! boundary is the wall, not the eaves!

Here's a more detailed explanation:
Walls as Boundary Markers:
When a house is built right up against the boundary of the land, the boundary usually runs along the outer face of the external wall.

Thank you, where did you find this tidbit?

OP posts:
Melroses · 17/03/2025 22:54

We have an extension on the boundary wall - it was an extension of the former garage wall which was there originally. The eaves definitely extend beyond (as they did before) and do not extend the boundary into next door's space.

allthemiddlechildrenoftheworld · 17/03/2025 22:58

ThisPinkCrow · 17/03/2025 22:52

Thank you, where did you find this tidbit?

@ThisPinkCrow

  • Eaves and Footings:
  • Eaves and footings may project beyond the boundary line, but they are considered part of the building to which they are attached, and the airspace between them belongs to the adjoining land.
  • Title Plans:
  • Plans attached to property deeds generally show boundaries at ground level, but foundations and eaves may extend beyond the defined boundary line.
  • Legal Boundaries:
  • The legal boundary is defined by the physical features on the land, not by the overhang of eaves or other structures.
RoastDinnerSmellsNice · 17/03/2025 23:00

ExIssues · 17/03/2025 22:05

Putting insulation on the outside of an old house will make the damp worse...it needs ventilation not insulation

I agree with this. Insulation is nothing to do with dealing with the damp problem, and would need to be made of something 'breathable', otherwise it will just seal the damp in. Are your neighbours aware of this OP, as you might go through all this, only to make their problems worse?

Also, your neighbours should pay for ALL costs to do with this, as none of it is advantageous to you OP.

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