What Kind of Insulation Should You Buy?
Once you have located the areas in your house requiring insulation, and
have determined what R-value is needed, you will need to decide what
type to buy. Some types of insulation require professional
installation, and others you can install. You should consider the
several forms of insulation available, their R-values, and the
thickness needed. Remember, for a given type and weight of insulation,
the thicker it is, the higher its R-value. The basic forms of thermal
insulation are summarized below. Here is some additional information.
Basic Forms of Thermal Insulation
Blankets: In the form of batts
or rolls, are flexible products made from mineral fibers. They are
available in widths suited to standard spacings of wall studs and attic
or floor joists. Continuous rolls can be hand-cut and trimmed to fit.
They are available with or without vapor retarder facings. Batts with a
special flame-resistant facing are available in various widths for
basement walls where the insulation will be left exposed.
Blown-In loose-fill insulation:
It includes loose fibers or fiber pellets that are blown into building
cavities or attics using special pneumatic equipment. Another form
includes fibers that are co-sprayed with an adhesive to make them
resistant to settling. The blown-in material can provide additional
resistance to air infiltration if the insulation is sufficiently dense.
Foamed-In-Place polyurethane foam insulation: Can be applied by a professional applicator using special equipment to
meter, mix, and spray into place. Polyurethane foam can also help to
reduce air leaks.
Rigid Insulation: Is made from
fibrous materials or plastic foams and is pressed or extruded into
board-like forms and molded pipe-coverings. These provide thermal and
acoustical insulation, strength with low weight, and coverage with few
heat loss paths. Such boards may be faced with a reflective foil that
reduces heat flow when next to an air space.
Reflective Insulation Systems:
They are fabricated from aluminum foils with a variety of backings such as
kraft paper, plastic film, polyethylene bubbles, or cardboard. The
resistance to heat flow depends on the heat flow direction, and this
type of insulation is most effective in reducing downward heat flow.
Reflective systems are typically located between roof rafters, floor
joists, or wall studs. If a single reflective surface is used alone and
faces an open space, such as an attic, it is called a Radiant Barrier:
Radiant barrriers are sometimes used in buildings to reduce summer heat
gain and winter heat loss. They are more effective in hot climates than
in cool climates. All radiant barriers must have a low emittance (0.1
or less) and high reflectance (0.9 or more).
