high ground level problem with neighbouring new build house

Hi all
Would appreciate any advice. I live in a cottage built in approx 1890, with solid walls. I have had various issues with damp and recently had a detailed damp survey by an independent surveyor. One of the issues he has identified is the high ground level of a new house next door (finished around 18 months ago).

The external ground level is roughly 1'6" higher than mine (the street is on a hill), and approx. 1' above my internal floor level (and above my DPC).

The situation is the the neighbour has a patio and then a strip of approx 6" of gravel which buts directly against my external wall (the wall is the boundary). I say gravel, the strip has a gravel covering but it turns out that this is only the top inch or so, and below that is basically sand - saturated sand at that. So this block of wet sand sits against my wall. There does seem to be some sort of bitumen coating on the base of my wall which is hopefully resisting the water so some extent, but obviously is not ideal and I would like to rectify it.

I am going to speak to the neighbour soon, and I am also pursuing the builder (through their surveyor) as it seems to me they have not done what they said they were going to do according to the party wall agreement (I read it as showing that the final ground level should be level with my floor level). The previous property which was knocked down was further away and there was a empty patch between our properties with a lower ground level.

My question is, what resolution would be suitable? Is some sort of French drain or soakaway or other drain appropriate, with coarse aggregate above? Or is the only solution lowering the ground level. Would the whole patio need to be lowered or just the current gravel/sand trench? Water currently runs off the patio into the gravel/sand when it rains.

Thanks

View media item 104896
View media item 104897
View media item 104898
View media item 104899
View media item 104900

Dig a channel the total length of the wall and ensure it’s 6” below your damp proof course. Hack off your render to just above dpc level and finish with a bell mouth drip. Remove any walls abutting your external walls. Install a soak away system.

The neighbour has an obligation not do anything to cause your property to experience damp.

There are various options but they are for your neighbour to determine and carry out. And while these "might be this", "could try that" scenarios play out, things get worse and it drags on and on.

You could involve your council to act under their powers of Statutory Nuisance (EPA 1990), and this could require the neighbour to rectify the issue within 21 days, else face action in the Magistrates Court - which the council will do at no cost to you.

PropRepairAdvice said:

Dig a channel the total length of the wall and ensure it’s 6” below your damp proof course. Hack off your render to just above dpc level and finish with a bell mouth drip. Remove any walls abutting your external walls. Install a soak away system.

Click to expand...

Thanks for the reply. I'm already getting quotes for having the old render completely removed and either the pointing re-done or else a lime render. That was the other big recommendation from the damp survey.

Just in terms of the channel, once it's dug out and the render removed, is it still ok to have the ground level be high? As in, if a soak away is installed, does that get covered with coarse material back up to to the level of the patio (and above my DPC)? Or do you mean that there DPC needs to remain exposed? I'm just wondering how that would be possible as the neighbour obviously won't want a 18" drop at the edge of their patio for safety reasons (and they have a small child).

^woody^ said:

The neighbour has an obligation not do anything to cause your property to experience damp.

There are various options but they are for your neighbour to determine and carry out. And while these "might be this", "could try that" scenarios play out, things get worse and it drags on and on.

You could involve your council to act under their powers of Statutory Nuisance (EPA 1990), and this could require the neighbour to rectify the issue within 21 days, else face action in the Magistrates Court - which the council will do at no cost to you.

Click to expand...

Thanks for the reply. I'm speaking to the neighbour later today. I agree it's not for me to determine and carry out rectifying the problem. The reason I'm asking what the correct solution should be is that when he or the original builder come back to me with suggestions, I'd like to know if they are the right thing to do if or they're just cutting corners and doing the easiest thing that isn't the best for me.

The options are a physical barrier against the wall or a gap to keep all ground away from the wall from 150mm below the DPC level.

Physical barriers tend not to work in these circumstances, or work for a while before being compromised.

^woody^ said:

The options are a physical barrier against the wall or a gap to keep all ground away from the wall from 150mm below the DPC level.

Physical barriers tend not to work in these circumstances, or work for a while before being compromised.

Click to expand...

So given that the DPC is currently around 1' to 1'6" underground, there would need to be a trench between 1' and 2' deep between the patio and my wall. So is the best solution to leave the trench empty and have a fence so that the neighbour doesn't fall down the hole?

Neighbour or leaves and debris

Indeed. Sounds like you think the trench needs to be not filled with anything. In which case I would have to suggest the neighbour basically gives up 6" of his side passage...

Why don’t they just lower their paving along this section and it’s all sorted then.

PropRepairAdvice said:

Why don’t they just lower their paving along this section and it’s all sorted then.

Click to expand...

Probably my preferred outcome but they may not go for it. The patio wraps around the back of the house so you'd be lowering a section and introducing steps. Likewise the side door opens onto this section we are talking about, currently there are one or 2 steps down and this would mean more. Also from the front drive. So I can see why they might resist this option.

I’d put a claim in against the builder personally and get a party wall surveyor out as an independent mediator.

good luck

Thanks. The party wall surveyor who acted for me on the original agreement seems seems to think that all that needs so happen is the gravel layer should go deeper so that it is below my DPC. It's not even very coarse gravel! Maybe time to find a new surveyor.

If you’re in Bristol I’d take a look. Local surveyors direct website is pretty good.

I'm Hertfordshire unfortunately. But I'll try that website, thanks