Our Neighbour Wants to Build His Extension Next to Ours – What Rights Does He Have?

by: The Party Wall Surveyor


My neighbour has received planning permission to erect an extension to his property.  He intends to build his extension on the junction line.

We have a wall (wholly on our side of our property and which is our kitchen wall) which also sits on the junction line.  He originally intended to incorporate our wall into his extension but has now agreed not to do this following our objection.  Instead, he now wishes to build his own wall adjacent to our existing wall and has served a notice under section 1(5) of the Act.  Given the fact that our wall is actually part of an existing building rather than a party wall is his notice defective/does he need to serve a notice under section 1(5)?

I presume his new wall will require some kind of foundations – can he use our foundations, which will lie partially on his property or will he have to dig below our foundations and create his own? Does he have a right to seal the gap between the two walls?


Notice under section 1(5) of the Act is required if his new wall is to be built up to (but not astride) the boundary line.

The new wall will have to be built on its own foundations and if those foundations are to be deeper than your existing foundations notice will also be required under section 6(1) of the Act. Your neighbour will have the right to cut in to your wall so that a flashing can be inserted to waterproof the gap although that again would require notice – under section 2(2)(j).

You may want to re-consider your original decision and allow your wall to be enclosed – the detail will be much neater and you could request some compensation. Presumably the main parts of your properties are divided by a single wall so it would be no different to that.