I apologize in advance to the OP for drifting a little off subject.....,
Jayco's 2014 model year specifications (web site) one will find referenced three different roofing materials being utilized, it's model specific. The three materials are: "Alpha-Ply", "DiFlex", and "Rubber" (EPDM).
I recall that the Alpha-Ply material was a thinner/lighter material then the EPDM (rubber) material.
A recent JOF thread on Jayco roofing materials:
I don't believe any of the roofing materials presently utilized by Jayco has the fleece backing.