Help with flat roof options

[Stephen Lynch]

Hi all,

I'm working on my first BRRRR in Ohio and it has a detached garage roof (flat). Every roofer has recommended changing out the wood with new OSB, but they are all offering different options for the roofing material.

Options...
Reinforced EPDM .60mil with no fiber board
EPDM .45mil with fiber board
Flintlastic SPS 

I'm convinced EPDM is the way to go, but I'm not sure what the best practice is regarding the use of fiber board under the rubber? The garage is detached and is for storage only so it doesn't need insulation. I'm reading that fiber board is used for insulation between the rubber and the OSB, but I've also read it can help to avoid tears from falling tree limbs and such.

If the cost was the same would you go with .60mil EPDM w/o fiberboard or .45mil EPDM w/ fiberboard ?