Who is Responsible for Our Neigbour’s Boundary Wall Being Damp?

by: The Party Wall Surveyor


I moved into a property a couple of years ago where the adjoining property has a “sunken” extension built some 15m out into their garden – so their living room wall now runs down one side of the garden (it does not have any overlooking windows).  The two properties are completely separate, there is a small gap of a few centimetres between them where they are adjacent, so the extension and facing wall is definitely built entirely on their land.  There is no party wall agreement and I do not have a fence on my side of the boundary, so their wall is the edge of my garden.  I think the original architect devised a “clever” scheme where the foundations of the sunken part of the extension start just far enough out to avoid coming under the scope of the party wall act.

Recently our neighbour reported that water had damaged their basement, it is unclear why though a strong candidate is use of a sprinkler/hose by us in our garden.  On examination, the damp-proof course of their wall is very close to the level of the garden turf, and some of the weep holes above the DPC looked like they may have become blocked over time.  However, the previous owners of our property did not use their garden at all, so it seems impossible to rule out some long-standing problem with the wall.  As the wall is on their land entirely, do we as adjoining owners have any responsibility for the wall, in particular to ensure that the level of the garden remains below the DPC and that the weep holes do not get blocked?  Whilst I don’t want to create a dispute with our neighbour and can resolve things amicably with them, I don’t want to end up taking responsibility for their wall and having to block off a strip of the garden (which is already quite narrow) just because the original builder didn’t leave any space for maintenance.


If the wall is built on your neighbour’s side of the boundary then it is not a party wall and any dispute that you have will be outside the scope of the Act.

When the wall was built presumably the builders backfilled the ground alongside it – they should have ensured that the backfilled ground was at least 150mm below the damp-proof course to avoid the possibility of bridging. If  a retaining wall alongside their new wall, or some other method of keeping the ground back from their wall was required then it should have been specified at the time.

Unless you have raised the level of your garden since the wall was built I can’t see how you could be held responsible.