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avoiding condensation/cathedral ceiling/metal roof

here are the facts: 60 year old home; cathedral ceiling; 6" rafters; I want to tear out the existing insulation(black paper on both sides of brown fiber); and ceiling tiles. From the top we have metal roof--furing strips--shingles--rood deck.

How do I re-do and avoid condensation.....and can I use can lights?

Re: avoiding condensation/cathedral ceiling/metal roof

You avoid condensation by having air space / ventilation between the roof sheathing and the insulation. This means some sort of eave and ridge venting. In a confined space as yours, both ridge and eave venting are a must. You can also add sheet insulation to the inside surface of the rafters, just under the drywall. Celotex is a good example. You can get a nice R rating with minimal thickness. If you double up the sheets, laying them without lining up the seams, and taping the seams shut, you can seal out any drafts through the ceiling.

The ceiling on my garage apartment is insulated that way. It does make drywalling tricky as you have to know where your rafters are.

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