| Attic Insulation
| -Fiberglass
Insulation Placing the
fiberglass insulation between the attic floor joists
effectively insulates the lower portion of your home and
avoids your using added energy to heat unused attic space.
Use this method if you don't plan to convert your attic
into living space.
Begin by
unrolling the insulation, paper face down, toward the
heated area of the house, between the joists, starting in
a corner. Use a stick to tuck it into the comer, but be
careful not to compress the fiberglass. If there are
soffit vents, leave a space at the eaves for air
circulation. |
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The greatest concern comes with infiltration of the heat from
the rooms below up through any cracks that may occur around
the insulation. Therefore, be very careful about fiberglass
insulation the way you
install the fiberglass insulationaround any obstacles in the joist space.
These include plumbing, piping, heater ducts, chimney stacks,
or the bridging. Cut the fiberglass insulation to fit snugly around the
object.Note: Unfaced
fiberglass must be used when working around heat sources like
a chimney, flue, or heating duct The paper facing on most
insulation is flammable. A 2" air space between the chimney
and the insulation is recommended. With prefabricated flues
and chimneys, check the manufacturer's recommendation. |
| You can cover all
electrical junction boxes (but not electrical fixture boxes)
because they do not give off heat. Again, do not distort or
compress the fiberglass. Leave about 3" around recessed
lighting fixtures for air to circulate and to keep the fixture
cool. Wrap pipes separately to cut off air passage around them,
and stuff scraps of fiberglass into small, hard-to-cover areas. |
If one layer of fiberglass batting between floor joists does
not meet the value you need, a second layer of fiberglass
insulation can be added on top of, and at right angles to, the
joists. There is less thermal loss with this method because
the joists are covered as well. Your concern here is to avoid
trapping moisture between the two layers by having installed a
vapor barrier between them. So, if possible, use unfaced
insulation for this layer. If not install the second layer
with the paper face down and puncture the paper barrier on
this second layer. Since you will have already taken care of
any penetrating problems, your main concern with this second
layer is that the batting fit good and snug, side by side and
end to end. Start this second layer butted against the bottom
of the rafters, beginning in a corner. Continue to install it
end to end until you get to the center of the floor or near
the stairwell. Then begin again at the opposite side and
install to the center again, to avoid walking on and
compressing the fiberglass insulation over the joists. Install
fiberglass insulation on the opening hatch door to your attic as well. |
Another method is to pour or blow in
loose fill or cellulose insulation up to the joists for an even
surface. Then unfaced or punctured batt fiberglass insulation can be
installed perpendicular to the joist system. A trouble light is
needed to help you see that hard-to-reach places are being
adequately filled with the cellulose. Blow in the cellulose to
fill the joist spaces past the top of the wood framing, to achieve
a higher R-value.
As you work back into corners and around eaves' vents, take
care that you do not cover any ventilating areas.
A long straight board will help even out
the cellulose. Drag it along the joists to push loose piles of
insulation into the spaces between the joists.
After completing your fiberglass
insulation , you
may find that your skin itches from fiberglass irritation.
I've found that vinegar makes an effective rinse when I bathe
or shower after working with fiberglass. It almost eliminates
the itching, which comes from the small particles of glass
left on the skin.
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