Improving the insulation in a closed roof cathedral ceiling.
IRFL
| Posted in General Questions on
On a closed roof cavity which currently is insulated with poorly installed fiberglass batts: If I pull out the fiberglass insulation, can I insulate with dense-packed cellulose with no roof ventilation, or will it cause a moisture or mold issue?
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Replies
There can be no moisture or mold issue unless vulnerable materials get wet. If the roofing is well-maintained and intact and the ceiling air barrier is complete (no unsealed penetrations, particularly recessed lights), then there can be no moisture accumulation.
However, depending on your local climate, an unvented roof will transmit more summertime solar radiant gain, will increase the peak roofing temperatures, and will be more vulnerable to ice dams.