Do you have
your roofing project?
|Click Here to
|Proud Member Of
known to the State of
California to cause cancer,
birth defects, or other
reproductive harm are
created by the combustion
of propane, use of hot tar
kettles and tar products.
Our industry is required to
comply with Proposition 65
known as the California
Heath And Safety Code. We
are required to give you
Loose-fill insulation consists of small particles of fiber, foam, or other
materials. These small particles form an insulation material that can conform
to any space without disturbing any structures or finishes. This ability to
conform makes loose-fill insulation well suited for retrofits and for places
where it's difficult to install some other types of insulation.
Types of Loose-Fill Insulation
The most common types of materials used for loose-fill insulation include
cellulose,fiberglass, and mineral (rock or slag) wool. All of these materials are
produced using recycled waste materials. Cellulose is primarily made from
recycled newsprint. Most fiberglass contains 20%–30% recycled glass.
Mineral wool is usually produced from 75% post-industrial recycled content.
See the table below to learn how they compare.
Cellulose Fiberglass Rock Wool
R-value/inch 3.2–3.8 2.2–2.7 3.0–3.3
Inches (cm) needed for R-38 10–12 (25–30) 14–17 (35–43) 11.5–13 (29–33)
Density in lb/ft3 (kg/m3) 1.5–2.0 (24–36) 0.5–1.0 (10–14) 1.7 (27)
Weight at R-38 in lb/ft2 (kg/m2) 1.25–2.0 (6–10) 0.5–1.2 (3–6) 1.6–1.8 (8–9)
OK for 1/2" drywall, 24" on center? No Yes No
OK for 1/2" drywall, 16" on center? Yes Yes Yes
OK for 5/8" drywall, 24" on center? Yes Yes Yes
Recommended Specifications by Loose-Fill Insulation Type
Some less common types of loose-fill insulation include polystyrene beads
and vermiculite and perlite.
Loose-fill insulation can be
installed in either enclosed
cavities, such as walls, or
unenclosed spaces, such as attics.
Installation usually involves using
special equipment that blows the
insulation through and into the cavity
or space. This includes the "two-hole
method," which entails drilling two
holes spaced vertically between the
exterior walls' framing studs. The
holes should be 2 inches
(5 centimeters) in diameter. Working
between each stud, drill one hole 16
inches (41 centimeters) from the top
the wall. Drill the other hole 24 inches
(61 centimeters) from the bottom of
the wall. Blow the insulation into the
holes and then seal the installation
holes. In conventional and cathedral
ceilings, insulation is easier to blow in
if an access opening through the
ceiling already exists. Otherwise, it may be necessary to drill holes in the
ceiling or between the roof rafters.
Installation is most commonly done by professionals who are experienced at
operating the equipment to ensure proper density and complete coverage. If
you'd like to have the insulation installed professionally, you should do the
• Obtain written cost estimates from several contractors for the R-value
you need. Don't be surprised to find quoted prices for a given R-value
installation to vary by more than a factor of two.
• Ask contractors about their air-sealing services and costs as well, if
If you want to install it yourself, you should try to obtain instructions and
safety precautions from the insulation manufacturer. Carefully follow these
instructions. You should also check your local building and fire codes.
Over time, loose-fill insulation can lose its installed R-value because of
settling, especially in attic cavities. Cellulose settles more than rock wool or
fiberglass—20% compared to 2%–4%. Therefore, if you use cellulose, install
20% more in an attic to offset the settling. Cellulose manufacturers are
required by federal law to provide the "settled thickness" on their bags. Some
even provide the "installed thickness."
Researchers say it's possible to install loose-fill insulations in wall cavities
without settling. If the cavity is completely filled with insulation at the proper
density, no significant settling should occur. A general density guideline for
walls is roughly 3.5 pounds per cubic foot (17 kilograms per cubic meter) of
wall cavity for cellulose and 1.5 pounds per cubic foot (7 kilograms per cubic
meter) for fiberglass or rock wool. These specifications are roughly twice the
density of horizontal applications.
Here's an easy-to-follow guideline to ensure that wall cavities are being filled
at a density sufficient to prevent settling: use roughly one 30-pound (13-
kilogram) bag of cellulose or about 15 pounds (8 kilograms) of fiberglass or
rock wool for every three wall cavities you fill. (Assumptions: 8-foot [2.4-
meter] walls, with 16-inch [41-centimeter] on-center wall cavities, and 2x4-
inch framing studs.)
To ensure quality installation, whether you hire a professional or do it
yourself, you should also look for voids and gaps, and fluffing.
Voids and gaps occur if insulation is installed at too low a density or if a
cavity isn't completely filled. Voids also occur if the installation holes are
improperly located between the vertical framing studs or if there are too few
Fluffing occurs when insulation is installed to minimum thickness but not to
minimum weight requirements. The result is a less dense application of
insulation that requires fewer bags. When insulation is fluffed, air passes
more easily through it. This means increased heat loss. Additionally, the
fluffed loose-fill insulation will eventually settle, resulting in a loss in thermal
resistance or R-value. Fiberglass is more "fluffable" than cellulose or rock
Intentional fluffing by unscrupulous contractors has been a problem in some
parts of the country. To avoid these problems, compare bids from several
contractors to see how many bags they specify. Count the number of bags
used during installation, either by you or a contractor, and compare it to the
instructions on the bag. The manufacturer should specify the amount of
insulation required to obtain a particular R-value per square foot (or square
meter) of space.
Safety and Health Considerations
Insulation blown into your ceiling cavities should cover the top plate of the
wall, but be sure the eave vents are not covered. These vents provide
necessary ventilation to your attic, and covering them could result in severe
Electrical devices and recessed lights (except "IC-rated" fixtures) require 3
inches (8 centimeters) of clearance from insulation.
Pipes for kitchen stoves, wood stoves, and furnaces should only be insulated
with fiberglass or rock wool because cellulose may smolder if flue
temperatures become hot enough.
Some observers contend that fiberglass particles can cause cancer if
inhaled. Others state that the fire retardants and insecticides added to
cellulose may be harmful to breathe. While the debate continues as to the
health effects of loose-fill insulations, it is important to protect yourself when
installing any type of insulation. Wear a quality respirator, protective
eyewear, and clothing such as goggles, gloves, long-sleeved shirts, and
pants to minimize contact with the insulation.
Insulation fibers can also be drawn into air distribution systems if the ducts
are not properly sealed, allowing the fibers to circulate within the living space.
Be sure to seal all of your home's ductwork, as well as any other openings
where insulation could leak out of the wall or ceiling cavities and into your