You need to serve notice to adjoining neighbors If you are doing notifiable works to your property such as but not limited to:
Raising or demolishing a Party wall or fence
If you are cutting into the party wall to place a beam (as in Loft conversion)
Inserting a damp proof course, even at your side of party wall
Raising a party wall and need to cut or repair some parts
Underpinning the party wall
Weathering the building on the line of boundary
Excavating within 3 meters of neighbor structure to the depth lower than their foundation
Excavating within 6 meters of neighbor structure to a depth below the line of 45 degrees drawn from bottom of their foundation.