Is there a height defining a low-to ground Deck, not requiring DOB permits?

Can anyone here clarify what is the minimum height that defines something as a “deck” , for DOB purposes, and is there a maximum height of a deck-like structure that does NOT require filing with DOB? In 2017 there were a few different postings here that referred to less-than 36″, but I want to ensure I am on very solid ground (no pun intended) if I don’t file.

I own the ground floor condo apart in a limestone building; my condo has an existing Legal diamondplate deck 34” high, 6’deep x 8’wide off the living room, and I have exclusive backyard access. My plan is to enlarge the deck space to the full width 10′, and 8′ deep (the yard is 40’+ deep). However because it is cost-prohibitive to “enlarge” a steel deck, rather that scrapping the ugly thing and building something new with drainage (maybe out of steel grate and overlaying either Ipe planks or Ikea tiles). Essentially I hope to replace the existing legal deck with a slightly larger one that meets all d eck codes, and if it is lower than a true deck, then I won’t technically be in violation by not filing. I need to be able to reassure my neighbors that all is legit.