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Attic Insulation
Adding insulation to your attic is one of the wisest home improvements
that you can undertake. Insulation not only provides a return on
the investment but makes your home much more comfortable for your family
and reduces drafts and illness.
Before you add any insulation to your attic,
you need to know how much insulation (R-value) is already there.
This is simply done by measuring the thickness of your attic's
existing insulation. Most older homes have between 3" and 6" of
fiber glass blanket insulation. This is roughly equal to an R-value
between R-9 and R-19.
Subtract the amount of your attic's existing
insulation from your area's recommended R-value to determine how
much more should be installed. R-25 insulation is great for adding a
second layer to existing attic insulation.
 Attic
Installation
First, some temporary flooring should be laid across the joists to
provide some footing, and a temporary work light should be used to
offer adequate lighting.
Install the insulation at the outer edge of
the attic space and work toward the center. This allows for more
headroom in the center of the space, where cutting and fitting can
be done. It's also a good idea not to get "insulated into a corner"
where it will be hard to get back to the attic entry way.
If the joist cavities are completely filled,
lay the new insulation in long runs perpendicular to the direction
of the joists, and use leftover pieces for small spaces. If the
cavity is not completely filled, use the appropriate thickness of
insulation to fill it to the top, then add an additional layer of
insulation in the perpendicular direction.
The insulation should extend far enough to
cover the tops of the exterior walls, but should not block the flow
of air from the eave vents. To make sure the eave vents aren't
blocked, attic vents or baffles should be installed to provide
unrestricted air flow from the soffit to the attic.
Insulation should be kept three inches away
from recessed lighting fixtures unless the fixture is marked "I.C."
(Insulated Ceiling), which is designed for direct contact with the
insulation. If insulation is placed over an unrated fixture, it may
cause the fixture to overheat and perhaps start a fire. Also, the
insulation should always be installed at least three inches away
from any metal chimneys, gas water heater flues or other
heat-producing devices.
Around masonry chimneys or other areas that
have small openings, stuff these spaces with small pieces of unfaced
insulation, which will not burn.
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