Foundations dilemma

[danr86]

I've down some exploratory digging prior to starting work on a new extension. It seems my neighbour has their extension's foundations (built ~6years ago prior to my purchase of the house) projecting on to my side - highlighted in blue.
Do you think I'll be able to build my extensions immediately next to theirs and join them so I can build directly next to their extension (subject to usual party wall agreements etc) using normal strip foundations - I'll only be going up one storey? Or will I need to use piling / raft foundations instead?

Thanks

 

[Bonni]

You need building regs and what you propose won't pass.

 

[Notch7]

You can do an adjacent foundation touching your neighbour. You will have to build fully on your foundation, if you want to build with the brickwork over to the edhe you can do that, but you will need a structural engineer to calculate the offset load.

 

[John D v2.0]

regarding eccentrically loaded foundations, I asked our SE about building on the edge and he didn't even think about it and said it's fine for domestic

 

[^woody^]

Put the strip in then oversail the wall. There will need to be some gap in any case.

 

[Notch7]

regarding eccentrically loaded foundations, I asked our SE about building on the edge and he didn't even think about it and said it's fine for domestic

Well Ive seen enought trenches on the pizz or in the wrong place resulting in the brickwork setout being right on the edge of the founds.

Reality is a bit different from the drawing........its not easy digging out trenches at this time year, sopping wet soil, corners often collapse....

 

[John D v2.0]

agree reality can be quite forgiving. the original house is still standing and it's 2 storey just built directly off the clay with a slight corbel not far below the surface
The one foundation the SE was particular about was the pad for the column supporting one end of three steel beams for the upstairs, but even that only had to be 600x600 and going down a metre. If the pad wasn't there there would have been 10000x600 of foundations instead.