You can use 2x material laid flat or 4x material also as sleepers.
Floating roof top wood deck.
You can do a floating deck and is really your only option.
These decks are often referred to as floating as they are not secured in place as a stand alone structure.
A reliable roofing approved waterproof membrane may be the most essential component to extend the lifetime performance for flat roof deck assemblies designed as floating or pedestal systems.
Roof top deck construction building a deck over a flat roof is very similar to building a deck over a concrete patio.
Typically laid directly over roof membranes on smaller areas as a do it yourself option these 12 x 12 or 12 x 24 modular tiles offer a quick and easy rooftop deck flooring solution by simply snapping together each tile automatically aligned and precisely spaced thanks to the connecting tabs on the integral plastic base.
Rooftop decking attaches to treated wood sleepers separated from the roofing by strips of epdm.
Floating or pedestal roof deck assemblies can be an ideal low maintenance deck surface on high traffic areas when properly installed.
A properly constructed epdm roof should last 40 or more years.
Interlocking ipe wood deck tiles.
However i would highly recommend that you consider a that the epdm is lying flat on the roof subfloor without any sharp objects that can puncture the edpm once sleepers are laid over top and placed under load.
They are merely placed on top of another structure.