a friend who happens to do home improvements recommends installing insulation on
the underside of the roof. From within
the attic of course. I haven't been able to find a thing that suggests doin so
or not. All I've been able to assess is that
by doing so may risk rotting the wood perhaps of the roof. the insulation has
vapor barrier paper or batting with paper on the
bottom towards living space.
His thinking is that keep the heat from entering the attic. Id have to
aggree, but why is it that I don't see this practiced
in any other houses. I know that installing the insulation on the underside of
the roof is an incredibly tedious and difficult thing
anyone have comments
The common thought was to insulate the floor of the attic, or the
rafters of the attic, but not both. This was the theory before Central AC.
Now, that central AC is a common feature, the theory is to have a
channel between the soffit vents and a ridge vent, which is a passive
vent, and insulate the rafters, including that passive vent. Do you have
a Central AC in the home and it is mounted in the attic? Then you need
both. One to keep the cold from the living area ceiling in the winter,
and one to keep the hot air from the AC unit in the summer.
Others may disagree, but the dual insulation makes sense.
If insulation is installed on the underside of the roof then that
suggests a living space or storage area in the attic. My parents did
that so they could use the attic space to protect apples from
freezing. It is not a difficult job if the temperature is cool
enough to work.
In addition to the comments made I will add that in general it is better
to insulate the floor and vent the attic to help keep the roof cooler. If
you insulate right under the roof, the roof will get hotter and the extra
heat will shorten its life. Also the roof is a larger area so for the same
money you can insulate the floor to a higher R value and have a smaller
exposed area of transfer.
With HVAC equipment in the attic, I suggest it is best to spend your
insulation budget on insulating the equipment and air handling equipment
rather than the whole attic.
Normal practice in an attic not used as living space is to insulate
the attic floor, between the joists to insulate the living space from
the unconditioned attic space.
If you want additional help in keeping heat out, the appropriate
technique for the underside of the roof sheathing is a radiant
barrier. Perhaps that is what your friend was talking about. But
this is a foil type product, not traditonal insulation.
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