Marks on party wall

[rebeccat]

I live in a privately rented ground floor flat, part of a small block of two-storey flats. Over the last few years, one part of my living room party wall has developed what look like cracks. Can anyone diagnose what could be causing these? Damp, minor subsidence? Is it likely to be serious? Each flat has a different owner, so it would be far from straightforward to allocate responsibility for repair work.

 

[Notch7]

Looks more like damp causing efflorescence to me

I can see it’s in a line but that might be plaster cracking, not wall cracking.

external images of the overall building, with that wall would be much more helpful.

I wouldn’t worry, severe cracks at the corners of door and window lintels are more indicative of subsidence, or in walls, probably diagonal cracks or cracks that taper.

 

[rebeccat]

Thanks for that advice. I can see no other evidence of this internally or externally, so it seems to be the plaster.

 

[tell80]

Is the background an abandoned chimney breast?

 

[rebeccat]

Is the background an abandoned chimney breast?

I'm unsure. The photo attached shows my ground-floor flat. My party wall, which is where the problem lies, is perhaps a little to the right of the TV aerial (I share the sloping-roof porch with the flat to the right).I see on the apex of the roof what could be four vents for gas appliances, although my flat has none, just a supply to the wall (white boxes bottom left of photo). Could there be a water leak down that vent?

 

[tell80]

No, i dont think its anything to do with the gas vent.
I'm still uncertain about exactly where the damp damaged plaster is located in your flat?
The porch roof might be the culprit but from your pic I dont see anything wrong?
The upstairs flat might be also be a culprit - and the other side of the party wall?
Does the line of damage go down to a solid floor?

To cut to the chase, you could hack off all the affected plaster back to masonry, and then make good with a sand & lime render @ 4:1.
This would probably give you a few years free of damp signs. It wouldn't eliminate the cause of the damp.

FWIW: google " drip mouldings" and think about having one above the porch door.

 

[rebeccat]

The damaged plaster is on the ground floor front room (the one with the large window) in the centre of the party wall. It is not visible outside and has no connection with the sloping-roof porch. It is from about halfway up the wall to the ceiling. The floor is MDF, not solid. There does seem to be a gas vent exactly behind the damaged wall and the fault does not extend below it, so I'd think there'd be a connection.

I've informed my landlord, so any remedial action is up to him and/or the owner of the flat upstairs. As my landlord has never inspected his property since I moved here in Jan 2017, I doubt he's in a hurry to act.

 

[tell80]

So you are saying that there is "a gas vent" the other side of the party wall in your RH neighbour's flat?
But, from your pics, there is no sign of any previous gas appliance or vent on your wall surface?
You might be well right but investigations in all four RH flats, & the loft would be necessary to determine exactly where the water is coming from?
Has your RH neighbour allowed you in to have a look or have they complained of water damage on the party wall?

 

[rebeccat]

It appears from the party wall itself, in a position covered by an unused electric heater attached to the wall, that there is a long-ago blocked vent that might have originally been for a gas fire and which I can only assume connects through the roof space to one of the four rectangular objects on the roof - presumably vents. You're right about the investigations, but as a private tenant this is neither my duty nor my responsibility. It's causing no problems for me apart from looking unsightly, so I think we can leave this matter for now while I await my landlord's response.

Many thanks for your helpful comments.