Party Wall Act - single storey back addition extension

[Towers64]

I’m having foundations dug to 1200mm at the back of my Victorian house ( the original property will have ltd foundations ). I have a side access with my neighbour which is 2.12 m wide. He is 0.45 m higher up. The foundation will commence against our existing 2storey back addition built in~1980 and approx 2.6 m from his underpinned back wall and progress further away from his back wall by another 1.5m. His house is also Victorian and was underpinned 50 years ago. My neighbour has brought to my attention the potential for subsidence on his side whilst my foundations are being dug. Any ideas of risk & likelihood of him experiencing further subsidence, given his house was previously underpinned?

 

[^woody^]

So many variables so no-one can state any level of risk other than there being some.

Irrespective of whether you follow the Act or not, your duty to prevent any disturbance of neighbouring foundations remain. Your contractors should take all practicable precautions when excavating and prepare their own risk assessment and method statement under CDM regulations and common law tort.

You would be wise to follow the PW Act and arrange pre-construction condition surveys.