Neighbours' extension gutter discharging over our roof - not in party wall agreement

[NCXo82ike]

Hi All.

We have recently bought a mid-terrace property and have plans to extend to the rear. We have a problem with the neighbours rainwater drainage, which uses our property and would be blocked by any extension we built.

 

Our next door neighbours have already created a garden room, built less than 10 years ago with a parapet party wall and multi-pitch roof. We have a small, original, singe storey pitch roof. There is a gulley drainage on their side of the parapet. The rearmost half drains to the rear edge of their property but the closest edge has been intentionally built so that the drainage runs over our pitch roof. I have attached photos and a schematic.

 

There is a party wall agreement the drainage from this pitch roof apparently runs around the party wall then into a soak away in their garden. The document we have relating to the party wall makes no mention of this drainage. It seems like a strange setup that no owner of our house would agree to, but the house was previously let by a disinterested/cheap landlord. If we build a matching extension, this water would have nowhere to go.

 

We have a good relationship with the neighbours but before addressing this I want to know where we stand. With no written agreement for this setup, could we demand they fix this?

 

We would reconfigure all our drainage whilst building an extension and would not need to make use of their soakaway any longer.

 

 

Many thanks in advance.

 

 

 

 

Edited May 14, 2021 by NCXo82ike

[joe90]

What an odd setup and difficult. Why would they create an upstand half way along their gulley?. I suppose you could insist they alter their roof to take their own rain away. IMO that party wall should have extended back to the house rear wall (but it’s not ?‍♂️). With your extension would you have a similar gulley but discharging to the rear of your new build? If that’s the case you could accept (in the vein of neighbourly love!) to accept the small amount of rain from that rear area!. Depends how strong arm you want to be with your neighbours?

[saveasteading]

That is all rather beautifully built, by the looks of it.

The amount of water off their rear half is quite low, but very deliberately controlled onto your roof.

 

The upstand halfway ensures that you normally get only that area of water, but in a downpour, or if a pipe is blocked, it can overflow back to yours.

It is quite clever in protecting the neighbour's property.

The upstand idea is something I have dome a few times to send water the way I wanted, ( to barrel for example) but allow full flow in extremes.

Without getting into the legalities, you might have to agree to revise this arrangement. Assuming that their forward downpipe cannot take all the water, then you will need another solution.

That will depend on what you want to build. could be a pipe picking up that water (best not) or an additional outlet or overflow from their eaves gutter.

The gutter looks substantial for the area of roof. What about the downpipe?

[epsilonGreedy]

13 minutes ago, saveasteading said:

That is all rather beautifully built, by the looks of it.

 

 

Defo some posh roofing and lead work there. Nice bricks too, I am thinking Yorkshire or North Lincolnshire, we call those bricks Langworth Yellows where I live. 

[Carrerahill]

27 minutes ago, NCXo82ike said:

Hi All.

We have recently bought a mid-terrace property and have plans to extend to the rear. We have a problem with the neighbours rainwater drainage, which uses our property and would be blocked by any extension we built.

 

Our next door neighbours have already created a garden room, built less than 10 years ago with a parapet party wall and multi-pitch roof. We have a small, original, singe storey pitch roof. There is a gulley drainage on their side of the parapet. The rearmost half drains to the rear edge of their property but the closest edge has been intentionally built so that the drainage runs over our pitch roof. I have attached photos and a schematic.

 

There is a party wall agreement the drainage from this pitch roof apparently runs around the party wall then into a soak away in their garden. The document we have relating to the party wall makes no mention of this drainage. It seems like a strange setup that no owner of our house would agree to, but the house was previously let by a disinterested/cheap landlord. If we build a matching extension, this water would have nowhere to go.

 

We have a good relationship with the neighbours but before addressing this I want to know where we stand. With no written agreement for this setup, could we demand they fix this?

 

We would reconfigure all our drainage whilst building an extension and would not need to make use of their soakaway any longer.

 

 

Many thanks in advance.

I think the first thing I would do is ascertain what I was going to build then look at how the two can co-exist - if it would add significant cost to my build to solve then I would look for another solution or investigate input from next door, if it was going to be negligible or a small cost I would just get on with it and accept some water.

 

I can help but thinking that in an ideal world you would drop that wall, form one gulley running to the rear and then build your roof like theirs having created a central gulley for you both but I am almost sure your neighbour is not going to want to rip their part up and redo it - unless you opted to pay for it as part of your works because it probably won't alter cost much, you need to do something their regardless.

 

My initial thoughts are, if you built a matching extension, you could possibly leave that wall, build an identical gulley on your side (with no central upstand!) and ensure sufficient fall to the rear of the your building and deal with that water in a conventional way. You are going to need to deal with the upper roof run-off anyway as it stands because you are currently discharging over your section of roof, so I think I would not get to hung up about this. 

 

I would say that trying to get them to change things at their cost on their side to deal with their run-off is probably going to sour your good relationship and that I don't think it would be a costlier exercise to build a roof to suit this - I also think a near mirror image of this extension would work well and keep some continuity between the properties even keeping them looking all original, with the only exception of your roof gulley being 5-10mm lower at the top and falling away sufficiently to drain the gulley. 

 

Another thing to consider is that anything you do that impedes their run-off and leads to leaks or issues on their side will probably become your problem because you touched it.

 

Could you post an image of how the rear elevation looks, how does that gulley interface with the rear wall, guttering etc.

 

 

 

 

 

 

[NCXo82ike]

Thanks for all the great input. They have indeed had high quality work done, but I'm surprised it relies on the assumption that any future neighbours would facilitate continued drainage. Surely they cannot lay a claim to this (without legal agreement)?

 

Let's say I wished to build a flat living roof with a height of 150mm below the parapet (~2.85m): this would then blocked the drainage. If I understand correctly from @Carrerahill's comment- liability for damage then falls on us?  I expect we can strike a friendly deal- but surely we can insist that their roof is changed? I'm surprised they didn't build the wall all the way back as per @joe90- I'm starting to think it was cunning design rather than clumsy! However were I building this I would ensure we control our own drainage and will certainly be doing that at the other party wall.

 

The downpipe from ours which discharges onto our roof is just a condensate pipe from a boiler (which will be retired for a heat pump). 

 

The attached photos show the rear elevation including the discharge of the rear half of the gulley.

 

@epsilonGreedy I believe this are 'Cambridge Whites'- at least the original components. We're probably on a similar clay.

 

 

 

Edited May 14, 2021 by NCXo82ike

[Bramco]

It does beg the question - why on earth didn't they build the party wall right back to the house wall?

 

What's there that caused them to go within a couple of feet?

 

Is there a fire wall in that space between your lean to and their extension?

 

Simon

[joe90]

52 minutes ago, NCXo82ike said:

Let's say I wished to build a flat living roof with a height of 150mm below the parapet

This all depends if whatever you build gives you enough head height inside.  I would get your rough plan drawn up of what you want and see if it will fit with the existing drainage, if not talk to your neighbour pointing out that running their rainwater onto your property is not acceptable (and it never should have happened).Perhaps get a roofer or your builder to quote separately for modifying their roof fall to make them take their rainwater, which I believe is not rocket science (I could do it) and whilst you are building extend that parapet wall back to your house wall. The response from your neighbour could vary from ‘feck off’ to “yes we will change our roof”. Hopefully the latter ?.

[NCXo82ike]

@BramcoI'm pretty sure it's an original build, solid brick wall.

 

@Joe with a beam and block floor level with the existing house and an extensive or wildflower flat roof, we should achieve 2.4-2.5m of ceiling height. Their water crosses the boundary at essentially the level of our proposed ceiling. 

 

Thanks again for the answers.

[joe90]

41 minutes ago, NCXo82ike said:

Their water crosses the boundary at essentially the level of our proposed ceiling. 

then a conversation is needed, let us know how it goes ?

[NCXo82ike]

4 minutes ago, joe90 said:

then a conversation is needed, let us know how it goes ?

Thanks- I will.

[saveasteading]

Practically, you can easily close the 'overflow' onto your roof when the time comes.

From appearances the main issue is that their downpipe is rather small, especially with the flow splashing in from the gutter under discussion.

ditto yours but from a smaller roof. 

Also, with an internal gutter it is good practice to have 2 outlets in case one is blocked, but this gutter is big and the flow small.

I think the easy answer, if amenable, is to close off your 'overflow', see how it goes but possibly add another rwp to theirs or change to  a bigger one. Once the water is going vertically, it is sorted.

The ultimate test is always 'what happens if the gutter or pipe is blocked? In this case, if the plastic gutter overflows, then no harm is done. Or it would need a very big problem to block the lead gutter, but the consequences could be bad.....but they built it.

 

I suggest design what you want in principle, and then there will surely be a solution.

[joe90]

From a look at your pics, the upstand in the middle could be removed and it looks like the lead work towards the house could be raised to take “their” water down their gulley, it “appears “ the slates might not even need to be removed ?

[epsilonGreedy]

I would want to build onto that existing wall to create an internal feature facing brick wall.

 

In @NCXo82ike's position I would ditch the plan for a heat pump and put the money into replicating the roof design of the extension next door.

[NCXo82ike]

14 minutes ago, epsilonGreedy said:

I would want to build onto that existing wall to create an internal feature facing brick wall.

 

In @NCXo82ike's position I would ditch the plan for a heat pump and put the money into replicating the roof design of the extension next door.

Exposed brick is a nice option which segments an otherwise 10*5m box. 

 

There are probably varied thoughts on heat pumps. I calculate we'll save a little money over a 7 year horizon Vs mains gas, but only a little. The main rationale is having a decarbonised house ready for the (near) future. I don't want to spend £££ on refitting a whole house and not achieve that.

 

I do appreciate the quality of the work next door and wouldn't rule out copying the style.

 

@joe90 this is the solution I'll be pushing for.