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2nd WRB over exterior poly iso/xps on roof?

kabouterhout | Posted in Energy Efficiency and Durability on

Hi all- I’m a carpenter currently remodeling a small home in the Netherlands. The house is now framed and sheathed and has been wrapped and taped in a layer of Pro Clima Mento 3000 WRB/air barrier.  On top of the existing interior insulation, the roof plan calls for 2 staggered and taped layers of polyiso/xps totaling 12 cm (4 3/4″) followed by ventilation battens and a metal roof.
My question is since the house has already been wrapped and taped in Mento 3000 and the following layers of insulation will also be taped is there any reason why a second WRB over the insulation/under the battens would be necessary? Is the underlying hard insulation a good enough barrier against potential leakage if it is well taped and sealed?
Thanks a lot ahead of time for any answers, much appreciated.


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