Damp (soon to be) Party wall

[steshaw74]

Hello y'all,

Looking for a little advice.....
Neighbour built single storey extension last year astride the boundary line, which I am more than happy with as we agreed I would use the new wall for the extension I am planning too.

However, neighbour's extension roof is leaking and making the (soon to be) party wall rather damp.

Obviously, it'd be ideal if their roof leak was fixed prior to our build starting, however, this might not be possible as neighbours might, understandably, have other priorities in the short term........and my build is due to start in 2 weeks.

The intension for the wall, on my part, is to be used to attach stud work, Celotex, OSB (wall will hold kitchen units), dry lined then skimmed.

Is there anything, some kind of waterproof membrane perhaps, that can be attached to the wall and buried behind my studs etc to ensure the water does not seep through to my stud work, Celotex, OSB etc...?? Hopefully as a short term fix until neighbours roof is fixed.

Relationship with neighbour is great, for what it's worth.

Thanks in advance.

 

[JohnD]

offer to arrange a good local roofer and chip in to the cost.

make sure he's a good one with local recommendation from people you trust.

this is not good roofing weather, though.

 

[RedHerring2]

Exactly as John said, when you have your roof done ask the roofer to fix next door's, as long as it's not too great a problem, otherwise, re-consider then.
You will need next door's permission.

 

[steshaw74]

John/Redherring,
Thanks for replies.
What you suggest is ideal, however, I don't know if my neighbour would be in a position to have the roof fixed when my builder is putting my roof on.

I'm sure they will want to have it fixed soon but I was hoping to find some kind of fix that I can be confident of until the source of the problem is sorted. My roof will be a straightforward pitched roof whereas neighbour has a complex flat roof.

Also, my builder has scheduled my work and his subbies, so I'm not sure I want to annoy him or put pressure on him to fix something unaccounted for. It must be a bug bear of builders when customers say, "whilst you're here, could you fix this too.......".

 

[JohnD]

I suppose you could treat it like a damp cellar wall, and tank it before fixing metal lathing (not wood which might rot), insulation and drywall. Unlike a real cellar, it would not have water pressure which tries to force the tanking off the wall. Be sure to include lots or airbricks to ventilate the subfloor and cavity.

 

[RedHerring2]

I can't see any decent roofer putting a roof on a buildling and leaving water leaking onto the party wall. How are you going to know it's still the original leak and not your roof leaking?

If your neighbour's roof is flat, is it felted? Surely the fall should be away from or along the party wall? If it's along the party wall your builder is going to have to weather-proof the join anyway.