I'm building a new lower ceiling in a room with an existing vaulted
ceiling. The existing ceiling has R19 insulation with a vapor barrier
and vent baffles. This is covered by drywall. The existing ceiling
doesn't provide enough insulation for the winter or summer.
The new flat ceiling at 9 feet high will have R38 insulation covered
by drywall. Should the new insulation have a vapor barrier? If yes,
which way does the vapor barrier face? I'm thinking that if a vapor
barrier is used it could trap moisture between the old and new
ceilings. If I don't use a vapor barrier how do I secure the
insulation to the studs?
I live in Northern Ohio where winter temps drop to 0 degrees. Thanks
for your suggestions.
You're in my neck of the woods. What you're proposing to do will give you
an unventilated _room_ above your living area. Not advisable. Your
intake/exhaust for air movement will not be directed towards the area you're
enclosing. You will be creating more problems than the existing one.
You need to create an unfinished _attic_ and proper air flow with
intake/exhaust. Bigger mess yes, but do not try to short cut this project
on the labor end.
You do not want a double vapor barrier, in our climate the vapor barrier is
towards the thermal envelope.
I agree with gunner. You could remove the existing drywall, and
insulation. Build your new ceiling as planned and you could even recycle
that insulation (without the vapor barrier) by laying it on top lf the new
insulation. Assuming you have low vents that will be near the level of the
new ceiling you should do fine.
Thanks for your advice. I never thought that the dead air space could
create a problem. After thinking about what you said, it makes sense.
The enclosed area would heat up but there would be little way for the
heat to escape. I suspect the problem would be more of an issue in the
summer rather than the winter.
It seems like my only choice for this new ceiling is to do just what
you said, and that is to remove all the existing ceiling drywall and
insulation, and maybe the baffles too. This simple project is getting
more expensive (I'm not doing the work).
Thanks again for pointing this out to me.
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