How can I Design my Extension as to avoid the need to Serve Notice?

Question

In relation to the question asked below :
 
How Far Back From the Line of Junction Should I keep my New Wall to Avoid Serving a Section 1 Notice?
 
The Question above had existing foundations in place. If you didn’t have existing foundations in place, how could you go about extension design to avoid having to serve notice. 

e.g. Neighbours extension might have 600mm depth foundation, which would limit the householders depth to 600mm, could an eccentric foundation or solid slab then be used at that depth and the building line set back the 2-3 inches from the boundary line as you suggest in the original answer?

Left side Neighbour, right side proposed extension as p

xxxxxxx   pppppppp
x             x p             p
x             x p             p
xxxxxxxxOxxxxxxx
x                x              x
x                x              x
x                x              x
 
Also a new question (I think), at the point marked on the diagram “O”, ie my back wall past both the centre line of the main party wall, and the brick either side, ie the full thickness. In building an extension you would probably use a metal wall starter, is this classed as a party wall, in that its the same wall that extends all the way across the back of the house or is it only a dividing wall and any part of it.

Answer

Using a raft foundation would be one way of avoiding the need for a Section 6 notice – as long as you don’t need to excavate deeper than the base of your neighbour’s foundations Section 6 is not invoked. 

There’s no clear answer to the wall starter question. It comes down to whether the party wall ends at the internal or external face of the rear wall. We tend to include it on a party structure notices where other Section 2 works are being undertaken but personally the risk of damage is so low that I would not serve notice just for a wall starter. Also, if you are keeping back from the line of junction to avoid a Section 1 notice the wall starter will be barely over the line of the party wall.