The bottom line is, each co-op sets up there own rules to meet their needs that the board makes.
Most boards have some architects/designers on them and they mix up building code with the needs of the shareholders.
Many of the co-ops I work in are filled with writers and work at home executives, so, sound prooofing and workhours with chipping hammers are restricted.
Water is a serious concern for them as these buildings are like old submarines (always leaking). Therefore, when you submit a plan for raising a floor to accomdate moving a lead band, they say you can not do it because of the risk factor in adding length to existing piping. Code is of no concern to them.
I know that there is a little more politics going on here than usual. There are two architects on this board. One I know well. He obviouslly knows there is nothing wrong with adding a few inches to lead band and was willing to approve the work. However, there is another board member(ex-construction manager) who refused to give his approval. Apparentlly, the two have been fighting over other issues including there own apartments.
It realy sucks when people get personal crap involved with others.