can I put fiberglass insulation over rock wool?


The rock wool is contained in a plastic barrier - if I put the fiberglass over it do I need a vapor barrier or should I put the wool right over it?
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trapped between them since barriers are not 100% effective.
Don Young
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so does that mean I cannot put fiberglass over the rock wool since it's encased in plastic? Do I need to rip it down? This is in a Cape Cod so the insulation is hanging from the gables. I'm just concerned that 3" of rock wool is not an efficient amount of insulation.
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Just cutting slits will take care of it, remember slit both the top and the bottom.
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On Aug 23, 11:04 am, snipped-for-privacy@columbus.rr.com wrote:

slits at the top and the bottom are good enough to release the vapor? There are staples in the middle as well, should i put slits there too?
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Joe wrote:

was already a moisture barrier, so they put fiberglass (six inch thick) crossways across the rafters with no additional barrier. The show was on in the past month or so.
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