Fire rating increase with Denslgass over OSB – am I in for a drying/perm problem down the road? – GreenBuildingAdvisor

In planning a wall assembly on a new home, we’re tasked with adding some fire resistance to the wall assembly while not significantly expanding the wall thickness. 

By adding a layer of Denslgass /fire rated heating sandwiched between the OSB (Zip in this case) and the cladding, it seems as though we would be reducing the perm rating on the OSB. And this would create a massive issue down the road should the OSB generate condensation on the interior side of the sheathing. (We’re not in a humid  climate – this is in Southern California, nonetheless weird weather happens)

We’re thinking of adding a rain screen mesh between the OSB and Densglass. 

Any input is highly appreciated. 

cheers,