Water Ingress - Dry Rot

[Mad McIntyre]

Hi All, firstly apologies for the Essay!

I've got very slight but quite constant water ingress beneath the floor of my party wall of a 1933 Semi, which has caused dry rot to the whole subfloor in my kitchen.
Took a corner of the floor up to discover a few things - a shared water main running through the wall to next door - had united utilities out and they say no leak detected on it.
But next doors floor joist is completely black and sodden and there is a very slow trickle of water seemingly from their floor joist area back towards mine.

Neighbour (tenant) says she has no obvious water leaks on her side of the wall but has had other damp and water problems with the house and there are plans a foot for a whole new roof their side but no obvious water damage on the wall/upstairs on party wall, only below.

Had Peter Cox out who could not pin point the exact source of water and their assessor could only speculate that it's coming from next door, running down their obviously sodden floor joist and into my side but couldn't be 100%.
The pictures are clear that they have completely sodden floor joist/s and evidence that mine is getting constantly re-wet and drying out. I'm 99.9% in agreement but not sure the source of this water.

He also pointed out that my rear patio has been built up too high and breached the damp course, although some attempt with a membrane has been made to seemingly stop an ingress of water here. Remedial work suggested including increasing and altering the Air Bricks to increase ventilation and creating a drainage channel of sorts by angle grinding a sufficient gap in the patio to the wall and then set down to below the damp proof course filled with say pea gravel, makes absolute perfect sense. Although I would say the air flow was good anyway despite the half covered air bricks and evidenced by constant drying out.

I can accept the damp proof has been breached (previous owners work) and I am fully prepared to alter the patio as suggested, however the ingress of water was not necessarily pinpointed as from the damp course being breached and looks more like water from next door but still not sure.

Landlord of the house next door came round and before he even looked at his side for a leak or the area where he can see his sodden floor joists from my side, put the blame squarely on the breached damp course.
His theory is that water is travelling on top of the damp course and running across my rear wall to the right and through the party wall.

He was clearly being defensive and setting out with attack as best form of defence fearing it could become a blame game - at least it felt like that.
When he finally got down and had a look he then seemed less than sure and could only say he will investigate a leak on his side but I've heard nothing yet and it's still happening.

I am more than willing to hold my hands up if it is indeed my breached damp course that has caused this but I am not so sure and don't feel he is going to be honest if he does indeed discover a leak on his side.

I just wonder how plausible his theory is and how obvious to some of you more experience dampers! what the hell might be going on?
Obviously some correlation with the weather could be sort here but I've not been able to make that obvious link yet, the water seemingly comes in whatever the weather.

The picture outside shows the party wall divide and the box shows the area where the damage is inside in the corner.

[wes56]

You seem to have a common water supply but i dont see where your mains pipe branches off from your neighbours pipe?
do you have a water shut-off on your side? Is there a outside shutoff? inside mains shut-offs should be accessible and not be below floors or behind units.
the underground mains is in what material such as copper, galvanised or lead?
Utd Utilities will provide a free separate water services if you are on a common supply -at least they used to?

The neighbour's joists should not enter your side of the party wall. the party wall should not be breached at any level.
Your joist parallel to the outside wall is blocking ventilation from the two air bricks.
Underfloor ventilation should be through ventilation from the backwall to the front elevation.
more air bricks are needed, maybe telescopic air bricks?

How do you know the whole of your kitchen floor has dry rot, anyone been down and crawled the whole floor - the whole house suspended floors?
If you paid for an inspection did Peter Cox give you a report?
Usually when you treat for dry rot the affected joists and skirting/flooring will have to be removed and all plaster up the wall to at least a metre to be stripped.
The neighbourr's have a new joist which might mean they have had previous rot problems?

Is the ground to the right of you semi's high ground?

[Mad McIntyre]

Thanks for the input Wes, Peter Cox report attached.

Yes it is a common water supply, it runs up my drive splits to a T and covers the 2 semi's to my right, runs through mine where there is a stop cock above ground level and this pipe continues the length of my kitchen floor through the wall as pictured and ends with next door.

I've been told if I am to come off the shared supply then my neighbour would need to do it also and do it first as they are the end of the line so to speak, if I do it first it will cut off their supply and UU made every indication this is at our cost.
In theory if my neighbour did it they'd just free up my side of the line for my use only and not have the risky pipe running across my property length I guess?

The whole house has suspended floors and just going off the inspection as far as extent of the damage, the plaster was discussed and mentioned in the report.
But he did not get down there.

There are also air bricks situated on the front and Gable end walls and the DPC is not breached anywhere else so I'lm praying the rest of my timbers have remained dry and ventilated enough for the rot not to have spread.

Not sure what can be done about the air brick level in relation to the joist other than drop them down further but this potential French drain I'm looking to make would be very deep. Do I have any options here or is French Drain best way to go?

I noticed the air brick level in relation to the joist level also but it was not mentioned by the inspector or in the report.

When the water issue has been resolved I then have the unenviable decision of throwing circa £5k at Peter Cox to deal with it or doing the remedial work to the patio myself, then assessing it's potential of drying out. Once it's dry enough my fungal problem should go away then I will know what Timbers I need to replace.
God only knows how long drying my take, if anyone is familiar with Peter Ward (Heritage House) you'll know I am sceptical about the proposed use of chemical treatment, the inspector himself admitted that the dry rot fungi cannot live without a damp timber source for food which makes me wonder if their treated timber is even necessary and no doubt a large portion of the £5k.
They won't even necessarily honour their guarantee if it comes back under certain circumstances such as reinfection from next door, the guarantee was my main reason for getting in touch with them.

[Chop]

Quick heads up.. Can you omit the first page or take a screenshot , there a some data on there that is irrelevant.

[Mad McIntyre]

Quick heads up.. Can you omit the first page or take a screenshot , there a some data on there that is irrelevant.

I can't amend the document, I didn't wish to publish the lot but I'm so desperate for help I had no choice.

[Chop]

Maybe one of the mods can help you out. I've messaged them.

[Mad McIntyre]

Maybe one of the mods can help you out. I've messaged them.

Very decent of you, many thanks.

[Chop]

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[wes56]

moderators,

i've just submitted an extensive reply to this OP and after submitting my reply, and as i tried to leave this page an unkown pop-up appeared.
i didn't trust the pop-up and shut my PC down.
now on opening up the PC again there's no trace of the submission post i'd just made?

[moderator2]

No one else has reported any problems. Have you checked your device for viruses/malware ?

[wes56]

thank you moderator,
something similar happened some weeks ago on here with disappearing posts - only this time it was a pop-up that froze and captured the page as i tried to leave - the only options it offered were to click the pop-up, so having already submitted my reply to the OP i shut down the power to my PC.

[wes56]

There's still a few unanswered questions from my posts above?

Joists should not pierce the party wall at any level.
Your new, end capped joists will have to be installed at right angles to the rear wall to ensure through ventilation is not blocked.
You must have through ventilation from front elevation to rear elevation of the suspended floor.
Someone has to go under and crawl and inspect all the woodwork under the floor.

afaik, UU must provide separate external shut-offs for each household.
can you show a pic of the existing shut-off and its relation to the driveway branching off.
Do your pics show two supply pipes in the neighbour's sub-area?
The vertical pipe doesn't show a branch off?
Its important to locate the source of the water leak.

An underfloor inspection and work will almost certainly have to be done on your neighbour's side.
They have a new joist indicating recent remedial work?

Be cautious about accepting information from Peter Ward, some of it is sound and some of it no use.
Most people dont want lengthy drying out periods before remedial rendering of sand and lime at a 4:1 mix.
I dont like doing it but I spray chemicals, and treat new timber because i dont want call backs but it your choice.

[Mad McIntyre]

Joists should not pierce the party wall at any level.

1. You must have through ventilation from front elevation to rear elevation of the suspended floor.

2. Someone has to go under and crawl and inspect all the woodwork under the floor.

3. afaik, UU must provide separate external shut-offs for each household.

4. can you show a pic of the existing shut-off and its relation to the driveway branching off.
Do your pics show two supply pipes in the neighbour's sub-area?
The vertical pipe doesn't show a branch off?

5. An underfloor inspection and work will almost certainly have to be done on your neighbour's side.
They have a new joist indicating recent remedial work?

Cheers Wes,

Looking at next doors ground level at the rear I'd say it's higher than mine and this now concerns me a bit.
As for the party wall being breached, Peter Cox didn't even point this out, it didn't seem right to me but I've only just discovered it so who knows how long it's been like that but I'm guessing that must be rectified also.

1 - I have air bricks front to rear (and gable end), I suppose you mean I'll have to ensure there is nothing blocking this through flow underfloor, walls etc?

2. You mean of the whole house or just the kitchen area?

3. We have one shut off outside our properties and it will turn water off for 4 houses (2 semi's)
Apparently it's not uncommon for neighbours to be asked to store water for drinking/cooking while someone else on their shared supply line needs to turn it off for a period of time to complete work - this is what the United Utilities engineer told me.

4. I have attached a quick diagram of the water supply as I believe it to be from what I can see and what the UU engineer told me.
Yellow is my House and Drive - Red lines are the shared supply line, arrows shows shut off points, the one outside is just in front of my neighbours driveway.
Grey are my neighbours houses and driveway. I've put my neighbours extension and the garden area infront in Orange appears higher than the ground level my side.
As pictured the neighbours water supply runs up their wall stop tap near floor, no idea if anything else is branching off it and they are the end of the water supply this side of the shared supply so the main supply ends at their stop tap.
Landlord should be going in later today to have a good look his side, so we'll see what ideas he has.
I will ask him if he is willing to come off the shared supply and sort out a direct feed, it's just asking for trouble for the both of us, then patch up the hole (after the water has been identified and stopped of course)

5. I'll have to ask the landlord about the apparent new joists his side, although I don't necessarily believe anything he says.

He's coming up with excuses before he's even set foot in his own property to investigate a leak so that does not fill me with confidence and a previous dispute with the roof (which a couple of years later he is ironically replacing) I was told to serve him a party wall act and he was not interested in putting money into the property - I know he has obligations as a landlord and home owner but he's bigger and uglier than me so I'm sure he feels he can bully his way to the resolution he wants and costs him as little as possible, he's also in the groundwork trade himself apparently so probably thinks I'm not going to know any better. This is the feeling I am getting anyway but that's another story.

[wes56]

Has the landlord been?

I dont think you having control of your neighbour's water supply is allowed by Water Regs. An outside mains shut-off is different.
So far, nobody has found a leak in the supply pipe. Maybe its not the pipe.
The pipe in the pics is copper but I still dont know what material the supply that runs up the drive is?

You have a cavity wall and if the cavity is not blocked then moisture on the outer skin cannot get across the cavity to the inside skin.
To check this you will have to open up the cavity below your floor near the neighbour's and look for debris bridging the inside skin DPC.
I would suspect ground water from the higher ground beyond the very high yard boundry wall. The high ground will be affecting moisture on the neighbour's DPC, and maybe bridging his DPC and his air bricks?
Notice how your patio steps down indicating the ground is falling away beyond the steps.
You might be best dropping your patio below your existing DPC?

Crawl the whole house, as i mentioned above.
Paying esp. attention to the front elevation, the hall and the hearth.

There's something odd about your first pic - it doesn't seem to tie in with the other pics?
Its just rung a bell, you show that the neighbour has an extension - so the high boundry wall is actually an extension wall.
This could alter things but whats needed is a D&T survey of the neighbours house and extension.

[Mad McIntyre]

Hi Wes,

Q. Has the landlord been?

A. Yes Yesterday for about 25 mins - leak stopped and he's gone all quiet since funnily enough. Trying to get confirmation what he's done, I bet anything he claims he found nothing, let's see.

Q. I dont think you having control of your neighbour's water supply is allowed by Water Regs. An outside mains shut-off is different.

A. I am going to have to look into this, I can see why it shouldn't be allowed - I could contaminate their water source.

So far, nobody has found a leak in the supply pipe. Maybe its not the pipe

A. I never believed it to be the pipe Wes, UU checked it and confirmed it was not leaking, I always believed the leak was from some appliance or something else their side.

Q. The pipe in the pics is copper but I still dont know what material the supply that runs up the drive is?

A. Genuine question and not being flippant, why would that be relevant?

You have a cavity wall and if the cavity is not blocked then moisture on the outer skin cannot get across the cavity to the inside skin.
To check this you will have to open up the cavity below your floor near the neighbour's and look for debris bridging the inside skin DPC.
I would suspect ground water from the higher ground beyond the very high yard boundry wall. The high ground will be affecting moisture on the neighbour's DPC, and maybe bridging his DPC and his air bricks?
Notice how your patio steps down indicating the ground is falling away beyond the steps.

A. My property is indeed near the bottom end of a gradual slope.

Q. You might be best dropping your patio below your existing DPC?

A. Yes that's been suggested to create a French Drain, but I'm not sure any of it is necessary now the water has stopped, he clearly had an obvious leak, hoping for some confirmation today.
I will probably end up doing something here to free up those air bricks and ensure I am below the DPC just for belt and braces going forward.

Q. There's something odd about your first pic - it doesn't seem to tie in with the other pics?

A. Not sure what you mean here?

Q. Its just rung a bell, you show that the neighbour has an extension - so the high boundry wall is actually an extension wall.
This could alter things but whats needed is a D&T survey of the neighbours house and extension.

A. I agree but I'm not going to hold my breath, that's never going to happen unless I pay for it and he agrees to it unfortunately. He's a wrong un.