I have a need to install engineer hardwood flooring at an apartment of 4,000 sq. ft. with the largest area of 30’ by 40’ with 80’ corridors and the entire property needs about 3,150 sq. ft of flooring wood.

Unfortunately, the strata council have approved the above sound proofing requirements with floating installation + underlay.

I was told that glue down would prevent warping, shifting, shrinking/expansion.

Glue down does not have the above level of Strata approved soundproofing.

Any ideas of doing glue down but still meet the soundproofing requirements?

I am not sure, but you may be able to glue quarter inch cork then go over it with a sound muffling mastic to hold the engineered down..

Generally speaking, how large of a continuous span/area of engineered hardwood floor can you install with the floating method but maintain durability of avoiding movement, warping? I was told 25ft maximum??

each manufacturer will have different guidelines best to check with them.