I have a 25 year old home in Northwest Connecticut. I think I have a roof venting problem. My cathedral ceiling has 8 or 10" rafters and fiberglass insulation. There is ridge vent that runs along the length of the home and soffit vents. Nonetheless, I'm getting leakage an peeling paint which I attribute to condensation under the sheathing. I assume it's because the insulated space is not getting enough ventilation, ie: air movement. Do you agree, and is there anything that can be done at this point?

Len

Your not going to like me but if that insulation gets 5% of moisture in it it looses 95% of its insul properties.

Two major things go wrong with a cathedral ceiling is 1. not enough rafter thickness to obtain the proper (R) value for its Geo. 2. Is the venting from the soffit to full ridge vent is not addressed well to keep the min 2" air space in each rafter bay to stop moisture build. 3. Moisture barrier is so crucial in close applications on cathedral and if that was not used then again moisture.

Hear is a Geo map for (R) values. If you need (R) 30 then the rafter solidi be a 2x12 for 91/4" insulation and the air space full rafter width in each joist bay.

EERE Energy Savers: Insulation

What is insulation R value? | Insulation | Insulation Info

My question is how long have you had this house and did you have any Ice Dams on the edges of the roof which can also create your problem that showed up. Ice dams are also the direct result of poor or low insulation at the roofs edges by the eves.

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