precast plank cleavage membrane

huangyhg

precast plank cleavage membrane
when the floor finish is a cementitious tile, (i.e. ceramic, quarry, etc) a cleavage membrane, composed of a 0.7(+/-) mil poly, is recommended to separate the concrete topping from bondage to the structural precast plank.  thus, it is understood, that the concrete topping is no longer a structural component of the floor system.  this separation allows the prestressed plank to undergo anticipated camber "growth", after installation, as well as potential deflection, without forcing the tile, to experience the same structural movements, which would result in buckling, cracking and tearing of the tile and grout.
the question is, if only a portion, say 10 percent of an approximate 50' x 80' floor area is to be ceramic tile, and the rest is to be carpet, does it make sense to provide this cleavage membrane only beneath the tiled area when the balance of the floor areas concrete topping will be structurally bonded to the plank and its' movement?
i realize this may not necessarily be a structural inquiry, but, in my office, i work directly with the architects to prevent such potential problems.
any suggestions?  any experiences with this membrane?
thank you ...
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i would want the layout of the membrane to carefully follow the layout of specific planks so that you would avoid having any plank with partial bonded topping.  
i'd also want to separate the toppings (bonded and non-bonded) with joints.  
the problem is that your plank layout may not specifically follow your floor finish layout so there would be some odd conditions resulting from this layout coordination.
we have gotten away with no cleavage membrane if the tile area is small. if it is over a very small area, the tile would have a hard time arching up due to the plank rotation.