Rebuilding external wall on new foundations

[vik2001]

started a side extension, laid foundations with concrete. the main external wall knocked out and a supporting steel put in. if i cancel the extension i need to put the main external wall back up, the footings to this main wall is about 400mm or so. the foundations to build the brick work up has been preety smashed up due to a block and beam floor going in which will get removed.


BC say if i build the external wall back up it needs to be dug with foundations 850mm to match the foundation where the extension was going to go up. my concern with doing this is the original wall foundations around the rest of the house are about 400mm. so will rebuilding the external wall with 850mm foundation cause any issues like cracks, subsidence or any movement later on with house? see pic below

 

[^woody^]

If you rebuild a wall to exactly as it was before then the existing foundations are suitable.

What you are describing is a repair, and building control have no control over it other than it preform at least as well as what was there before.

 

[vik2001]

This is what I thought, the building inspector is being difficult and saying it must have cavity insulation, air gaps etc. If I do this I won't be able to match it with the existing cavity of original brickwork which had no insulation.