1890s terrace: penetrating damp where neighbour's roof/guttering meets our wall. Need help. Damp can be a major issue in the home. Find answers to questions or post your own here.

[wetrot]

Hello,

I first noticed some damp and mould upstairs under the bedroom window. Then noticed it had spread downstairs also.

There was a little bit of dodgy brickwork which is now fixed just above the gutter. Redone all the window sealant too. But that didn’t fix it. Then I realised that when it rains, water is just sitting on our wall, potentially related to the guttering on next door’s extension, see pictures.

Neighbour reckons it isn’t related to his guttering, but he’s having a roofer out to put in some roof windows and will ‘get him to look at it then’.

Any thoughts on root cause here? And who I should be contacting to fix it?

Thanks so much,
Pete

[haringeysashwindows]

Standing water = trouble
Water isn't so problematic as long as you create a pathway for it to run away - but once it can find its own way its amazing where it ends up
The roofing on the extension looks like it runs up against your wall and so any minor gaps will be exploited by the water - hydrostatic pressure. So the important thing would be to ensure the water is diverted away from your wall without engaging the wall ie a barrier of some kind.