I have an under-insulated roof above a "cathedral ceiling". The shingles need to be replaced this year. It occurred to me that this could be an opportunity to insulate from above.
Can it make sense to insulate above the plywood roof deck? Or to remove the plywood roof deck, add insulation, and re-install the plywood roof deck on top of that?
Accessing the insulation from inside would require ripping down and re-installing a perfectly good ceiling. I believe there's no more than 6-8 inches of fiberglass insulation in that ceiling, and in some places where there's an empty cavity, it appears the fiberglass has fallen out of position.
The home is in Massachusetts. I would love to hear from anyone on the theory and practice of doing this, and any real-world experience.