Digging footings next to existing footings

1 Oct 2007
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United Kingdom
Hi all,

I posted last week about my next door neighbour who wants to build a single-storey extension and attach it to our two-storey extension.

I am speaking with their builder tonight about the plans but I recall him saying on the phone that he wants to dig footings next to ours, and that they'll be deeper than ours (as our extension is 30 years old). Is there anything I should be worried about? Could he disturb ours in any way?

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Thanks, woody. I'll take your previous suggestion then of making sure that they build a stud wall straight off the slab on that side of the extension, requiring no footings to be dug. I'm going to insist on insurance as well. I have a feeling that tonight's conversation could get a little heated seeing as they want to start work THIS WEEK.
One can appreciate your concern about the footings. However, there is still the issue of the cavity tray above their roof level, which the Inspector will almost cetainly insist on.

Any bodge on that (which is a tricky job for the best of builders) will cause problems for both of you.

You also need to address the problem of the foundation to their rear wall; this will be below the level of yours (presumably).
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Are you sure a cavity tray will be required, they will be flashing to the wall not creating an opening in it.
Are you sure a cavity tray will be required, they will be flashing to the wall not creating an opening in it.

Yes, because the outer skin of brickwwork more often than not leaks when it rains (water can often find its way between the perpends of the brickwork, which are often not completely filled).
This penetration problem is the justification for building walls as cavity walls in the first place.
Any rainwater penetration through the outer skin won't affect the OPs property. but will affect the neighbours'. That's why Inspectors usually ask for one.
Just putting a flashing in might make the situation worse because it will disturb the brickwork

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