Is Party Wall Agreement required for new wall wholly on own land of semi-detached property

ravipal

We are planning a single story rear extension on our semi-detached property under permitted development. The extension will create a new wall adjacent to the neighbours boundary line, but wholly on our land. Even though the foundation will have to be excavated within 3 meters of the neighbour's property, as per our building regulation drawings, it will be to the maximum depth of 1 meters, which I believe should not be deeper than the neighbours foundation (the adjoining property is a  1950's 2 story house with no extensions).
Firstly is there an easy way to find out the depth of the adjoining property foundation ?
And if it is no more than 1 meters, then does that mean a Party Wall Agreement is not required ?
Would be most grateful for any information.

Doozergirl

You'd have to dig a hole next to their house.  Which is the same building as yours.  So if you dig a trial hole at the start of your new footings, you'll find out how deep the footings are. 

I always recommend that people build on the line of the party wall as it benefits both parties, ultimately.  If and when the neighbour extends, you share the same wall, both get the biggest extensions you can AND there's no danger of a weird damp gap between the houses in future.  And you get half the cost of your wall back, at the going rate at the time of next door's extension.  

The houses were built with a party wall, they should stay with a party wall.