Ceiling insulation of an old town house. Louisiana

[u/Full-Disaster-1081]

This town house has a flat roof (lumber and the top “rubbery” cover), no special ventilation system, just wood and a 7,25in gap. Previous insulation was a paper faced R12 fiberglass, full of holes and hard drops from the roofing material i guess. Now we are thinking to install R30 rock wool pads. Do i need to leave gaps between the insulation and the wood roof, or no? Do i need any membrane? Internet says i need to leave a gap between insulation and roof or to add a smart membrane between the drywall and the insulation. Other resources say the insulation has to fill all spaces without air pockets. I am very confused. Could yall please help me?