Figure 5-28.—Application of insulation.
the edges of the studs. After the drywall is installed or
plastering is completed, the film is trimmed around the
window and door openings.
Reflective insulation, in a single-sheet form with
two reflective surfaces, should be placed to divide the
space formed by the framing members into two
approximately equal spaces. Some reflective insulations
include air spaces and are furnished with nailing tabs.
This type is fastened to the studs to provide at least a
3/4-inch space on each side of the reflective surfaces.
Fill insulation is commonly used in ceiling areas and
is poured or blown into place (fig. 5-28, view C). A vapor
barrier should be used on the warm side (the bottom, in
case of ceiling joists) before insulation is placed. A
leveling board (as shown) gives a constant insulation
thickness. Thick batt insulation might also be combined
to obtain the desired thickness with the vapor barrier
against the back face of the ceiling finish. Ceiling
insulation 6 or more inches thick greatly reduces heat
loss in the winter and also provides summertime
protection.
Areas around doorframes and window frames
between the jambs and rough framing members also
require insulation. Carefully fill the areas with
Figure 5-29.—Precautions in insulating.
insulation. Try not to compress the material, which may
cause it to lose some of its insulating qualities. Because
these areas are filled with small sections of insulation, a
vapor barrier must be used around the openings as well
as over the header above the openings (fig. 5-29,
view A). Enveloping the entire wall eliminates the need
for this type of vapor-barrier installation.
In 1 1/2- and 2-story structures and in basements,
the area at the joist header at the outside walls should be
insulated and protected with a vapor barrier (fig. 5-29,
view B). Insulation should be placed behind electrical
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