I have large rectangle concrete floor with footings all around for a 2 leaf cavity wall which currently is 2 blocks above floor level. In otherwords the base of a garage with 2 rows of blocks up all round.
I want to put a 2 leaf cavity wall across the span of the floor to approx 7' high. I assume i'll have to cut the floor and dig to the level of the outside footings and lay footings for this new wall.
:?: Is it neccessary to join the new and old footings in some way or is it ok to pour to the same depth and height as the old footings, :?: do I need to use some steel as the span is 17', or is this necessary or is there some other way of doing it