My neighbour wants to build an extension 6" from our boundary (semi), will he need a party wall agreement? will the party wall then become the new boundary?
No and no, the extension is still on his property so it does not apply, if there is a fence already there and he takes it down, then you can use the strip of land but technically its still his,
Actually it depends. If the extension foundations will be built close to your existing building then yes, it might fall under the party wall act. How far away from your nearest wall will the new extension be?
