Backyard Shed

Hi, wondering if anyone out there has experience with building a shed/office in their backyard particularly in regards to DOB restrictions? I live in a 10 unit co-op and have exclusive use of the backyard (building is a converted brownstone). I am pretty sure the board will approve building something up to 120 Sq/Ft but I can’t find anything in DOB literature about restrictions on that for buildings with more than 4 units. It seems that as long as its “temporary” (which I take to mean not permanently affixed to a foundation) the DOB is okay with 120 sq ft in 1-4 unit buildings. I assume its the same for larger ones but would greatly appreciate any thoughts from someone who might have insight into this.