Potential causes for dampness - Party Wall

[agamemnon]

Hello,

 

We recently moved into a 1960s semi bungalow, we stripped the wallpaper and removed some of the outdated skirting boards, interestingly enough one of the skirting board was completely rotten and had some mould on it. The living room shares a party wall with the neighbouring house, their layout is mirrored, hence they also have a living room on the other side of the party wall.

 

We had someone come in with a protimeter and the reading were at least 11%, we aren't sure what the cause for the dampness is, and want to have it investigate further, there is a chimney on the same side, but the chimney plaster is in generally good condition without any sign of flaking or loose plaster. The floor has marley tiles, with no issues of them becoming loose. The DPM is bitumen and the marley tiles level the whole floor. 

 

All the waterworks runs on the other side of the property, so none of the pipework is theoretically close, however, I can't confirm this, because when I tried to turn off the main water supply, the stop valve started leaking, so reverted it to the original position and need to get that replaced to check for any leaking.

 

Any advise would be appreciated. Including some pictures. 

[joe90]

I had a similar thing, turned out to be a blocked rainwater drain on the boundary just outside, unblocked and the wall dried out.

[Radian]

1 hour ago, agamemnon said:

but the chimney plaster is in generally good condition without any sign of flaking or loose plaster.

 Is it possible that rainwater has been making its way down the chimney and is collecting/spreading out at floor level? I'd be looking at the condition of the chimney exit outside.

[agamemnon]

29 minutes ago, joe90 said:

I had a similar thing, turned out to be a blocked rainwater drain on the boundary just outside, unblocked and the wall dried out.

So none of the walls are external, one was historically but there is a conservatory on one side of the living room, then kitchen & hallway, third wall next to a bedroom, fourth and final is the party wall.

 

@Radian

 

So I had two wood burner installers after the handyman with the potrimeter, the handy man also said it could be the chimney, both chimney sweepers/stove installers said it’s likely coming from the floor or other side. Handyman went to the neighbours and their walls are in good condition. 

Edited August 30, 2022 by agamemnon
Merged into one post

[Roundtuit]

I'd guess the dpc has failed, but I'd probably start with the chimney and check capping, flashing and ventilation.  What's the topography like?  Are you on the same level as your attached neighbour?  Ground floor above external ground level?

[agamemnon]

7 hours ago, Roundtuit said:

I'd guess the dpc has failed, but I'd probably start with the chimney and check capping, flashing and ventilation.  What's the topography like?  Are you on the same level as your attached neighbour?  Ground floor above external ground level?

So the handyman will let us know about someone who can check the roof and chimney. We believe we are at the same level and house is above external ground. 
 

I am thinking of getting a moisture meter Protimeter seems to be standard, can I get any? E.g. brennenstuhl from Amazon?

[twice round the block]

Leaking back boiler in your neighbours property.

[joe90]

2 hours ago, agamemnon said:

am thinking of getting a moisture meter

Test above and below DPC to give a better idea if the DPC has failed and where the damp is coming from.

[agamemnon]

@twice round the block

On the other side of the wall is the neighbours living room, missus went over and and told me they have a bookcase there, no boiler or radiators nearby.

 

@joe90

 

Yes, will do that.

Edited August 31, 2022 by agamemnon

[agamemnon]

So everyone who is a damp surveyor went to a secret conference/holiday and can't get anyone closeby booked until at least next week.

 

One of my questions, does it matter if a dedicated "damp survey" needs to be undertaken, where you pay £100-150 for the survey, they then give you a quote for the work and if you go ahead you pay the additional difference. Or would you get a damp proofer, who looks at it and says "likely problems with damp proof course, this is the price...", from the sounds noone is going to go up to the roof to check, or do anything intrusive beyond visual inspection and moisture meter reading.

 

 

 

Or am I missing something about "damp surveys" and there is more to it?

 

For an update anywhere near the socket the moisture meter readings were 20-22% I took an hammer and chisel and removed all the cement and just above the floor level, moisture is more increased below and close to the socket instead of the chimney area.

Edited September 6, 2022 by agamemnon

[TonyT]

Check all the rain water goods, chimney etc.

 

check a known dry area, as some mortars can have conductive elements( common in mining areas I recall)  giving the impression of damp on the resistance/damp  meters

 

warch out for those tiles, they can contain asbestos.

 

get the windows open and get some ventilation into the building

 

 

 

[markc]

Damp proofing companies always “tut and suck” then sell you whatever treatment you will buy regardless of wether you need it or not.

A lot of  “surveyors”  are failed builders who know just enough to be dangerous and will always err on the side of caution in case you try to sue them.

get a decent local builder to take a look (offering to pay for their time) to give you an honest opinion of the affected area and what the cause could be.

[agamemnon]

24 minutes ago, TonyT said:

Check all the rain water goods, chimney etc.

 

check a known dry area, as some mortars can have conductive elements( common in mining areas I recall)  giving the impression of damp on the resistance/damp  meters

 

warch out for those tiles, they can contain asbestos.

 

get the windows open and get some ventilation into the building

 

 

 

 

So I don't know how to check the chimney stack, as I don't want to fall down checking it. I am based in hampshire, no mining close to where I live (as far as I know).

Tiles has had asbestos check done, as had artex ceiling as well, both negative.

 

 

22 minutes ago, markc said:

Damp proofing companies always “tut and suck” then sell you whatever treatment you will buy regardless of wether you need it or not.

A lot of  “surveyors”  are failed builders who know just enough to be dangerous and will always err on the side of caution in case you try to sue them.

get a decent local builder to take a look (offering to pay for their time) to give you an honest opinion of the affected area and what the cause could be.

 

Okay, great, would builders check the chimney stack, as the surveyor's aren't, and firestove installers mainly would take a picture.

[agamemnon]

On 06/09/2022 at 21:52, TonyT said:

Check all the rain water goods, chimney etc.

 

check a known dry area, as some mortars can have conductive elements( common in mining areas I recall)  giving the impression of damp on the resistance/damp  meters

 

warch out for those tiles, they can contain asbestos.

 

get the windows open and get some ventilation into the building

 

 

 

So was finally able to get a roofer on the thursday, the chimney stack had loose masonry, the cowl was gone, so getting that replaced.

 

We want to dry the wall, should we get a dehumidifier for that? Buy a used one from fb marketplace?

[TonyT]

Just hire one for a bit. But it can take months to dry out 

 

just make sure you have cross ventilation 

[agamemnon]

The only thing is that we want the plasterer to start the work on the damp wall, hence we wanted to dry it a little bit. I looked at hiring but the price comes to the same as hiring for a week as buying second hand. 

[Simplysimon]

part of your problem is that you don't know whether it was the missing cowl and loose pointing which was causing the damp. it's possible that it was, though an absence of damp further up the wall would suggest it may not have been. as @markc said get  builder out to check. the other option is to dig out below dpc to see if there is high moisture level below which could potentially show a failed DPC.

[agamemnon]

Sure, there are plenty more experienced people on this forum than myself. So will go with the majority.

[TonyT]

Progress!!

 

I have a dehumidifier, had some damp in the previous house, this helped solve the problem, I use it now to dry the washing in the spare room , so the dehumidifier could come in handy!!

 

 

 

[agamemnon]

The problem overall was the render bridging the bricks above dpm with below dpm and the concrete floor. 1” wide chase along the walls solved the issue.