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Roofing/cathedral ceiling insulating


QUESTION: I have cathedral ceilings (no attic). Just had a new roof installed. I have a ridge vent and soffit vents.  However, I also discovered part of my moisture problem is condensation due to improperly sealing on the inside. I am about to repair parts of the ceiling inside and I want it done correctly this time. I have a gable roof with a carport attached to the garage on one side and a fireplace in the middle of my house. I've read there are two ways to insulate this kind of ceiling. Since there is no ridge vent where the chimney is should this part be insulated differently?  Should it be totally sealed since this part can't vent properly at the top?

ANSWER: I don't know what you mean by improperly sealing on the inside. What are you trying to seal? Condensation usually happens when you have heated air hit an ice cold ceiling or roof. The ceiling should not be cold. It should be insulated. If it is insulated, how are you doing the venting as there is no space in the ceiling unless you use baffles.


---------- FOLLOW-UP ----------

QUESTION: Yes, heated air from the inside is escaping through closets, light fixtures, skylight, etc. It is insulated. No baffles but an inch or two air space between insulation and roof.   I plan on making sure ceiling is airtight everywhere on inside and putting in baffles when repairing but should I use them where the chimney is even though it can't vent at the top?

You need to seal off those spots where heated air is escaping. If there is an area where the roof does not vent you still want to seal off the inside or you have heated air that you paid to heat just going right through the ceiling. Also, be careful - you cannot put combustible materials up against a chimney.



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Brad Zacharia


All aspects of residential Roofing. This includes shingles and flat (low slope) roofs. I have knowledge in the installation as well as the design of roofs from an engineering standpoint.


I have been doing roofing for 40 years. This was my father's business and I took it over in 1980.

I have written responses to artcles that I felt needed a response to and those responses have been published in roofing trade magazines.

BSEE Drexel University

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