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dpb

On 12/18/2014 8:16 AM, wrote:
I live in CT, in a 100+ year old house. We have hot summers and COLD
winters. I believe that our attic floor was previously insulated, as
our house winter temperatures are easily controlled. Still I cannot
easily verify that insulation. nor amount/ depth - as there is
hardwood flooring in place.

There is no insualtion, on the attic roof insides. I would like to add
insualtion, and looking for guidance. What should I buy for
insualtion, which side facing the roof. Do I need to take efforts, to
provide any air flow ? (There is no roof peak vent). Should I use a
vapor barrier, over the new insualtion?

Would there be any issue/ concern, if I then put drywall over the
insualtion, to make the attic into a finished room?

Thanks for the advise offered. - joe

http://energy.gov/energysaver/articles/where-insulate-home

Your first issues are to stop all air pathways from the heated space(s)
to unheated. Insulation of the fiberglass type does virtually nothing
if there's any air movement at all thru it.

There are real possibilities of introducing condensation surfaces by
have double layers of insulation in attics in particular. Since you
apparently have an insulated ceiling now/future floor, you need to be
careful you don't turn that into one of those areas where cold
infiltration along the edges of it allows condensation since if you
finish above it will now also be heated space.

As another said, if you are going to finish the attic into heated living
space, likely it will be more efficient if there's the height in
sidewalls to build another ceiling rather than insulate clear to the
roof line itself. If you're _NOT_ going to add heated space then you
want to simply add more on what is now the attic floor.

You can guesstimate what's there pretty well by looking at the thickness
of the opening to get up there. If it's a framed hole w/ a ladder,
should be relatively easy to see what the ceiling/floor joists are. If
there's a finished stairway, still should be able to get a
measurement/estimate of the distance between the ceiling below and the
floor above -- subtract for the flooring and ceiling thicknesses and you
should be able to tell if 2x4, 2x6, 2x8 (nominal sizes) was used.
Assume either blown or fiberglass or perhaps rockwool depending on when
you think such insulation may have been added and whether know if the
flooring was in place first or not and can get at least a reasonable
guess of what the R-value will be...

Also whether you've got enough floor there to actually convert to living
space without additional structural work...

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