to Insulate in a Home*
For energy efficiency,
your home should be properly insulated from the roof down to its foundation.
This includes the following areas:
Seal all attic-to-home air leaks. Most insulation does not stop airflow.
Duct exhaust fans to the outside. Use a tightly constructed box to cover
fan housing on attic side. Seal around the duct where it exits the box.
Seal the perimeter of the box to the drywall on attic side.
Cover openings-such as dropped ceilings, soffits, and bulkheads-into attic
area with plywood and seal to the attic side of the ceiling.
Seal around chimney and framing with a high-temperature caulk or furnace
At the tops of interior walls, use long-life caulk to seal the smaller
gaps and holes. Use expanding foam or strips of rigid foam board insulation
for the larger gaps.
Install blocking (metal flashing) to maintain fire-safety clearance requirements
(usually 3 inches) for heat-producing equipment found in an attic, such
as flues, chimneys, exhaust fans, and light housings/fixtures unless the
light fixtures are IC (insulation contact) rated. IC-rated lights are
airtight and can be covered with insulation.
Make sure insulation doesn't block soffit vents to allow for attic ventilation.
Check the attic ceiling for water stains or marks. They indicate roof
leaks or lack of ventilation. Make repairs before you insulate. Wet insulation
is ineffective and can damage your home.
a conditioned basement, only the walls need to be insulated. The basement
ceiling may be insulated for noise control between floors. "Conditioned"
means the space is heated or cooled by a furnace or air conditioning unit.
begins, a ventilation baffle should be installed at the eave of every
joist, to make sure the ventilation space is not blocked by insulation
2. To install the insulation, push the material up between the rafters
until it's flush with the edge of the wood. If a faced insulation product
is being used, the facing goes toward the inside of the house -- the warm
side in heating climates. At least one inch of ventilation space is required
between the insulation and the roof deck. Some local codes require even
more vent space, so find out what's called for in your area.. If a standard
insulation batt is being used, or if the code requires more vent space,
install ventilation baffles along the entire run of each rafter cavity
in order to ensure a vented installation.
3. 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.
the insulation with the vapor retarder toward the warm side of the structure
in heating climates. In a vented crawlspace, the warm side is usually
up, closest to the floor
should be installed all the way back at the end of each joist run so that
it touches the band joist. You want complete coverage under the house.
There will usually be a narrow joist space on the walls that runs parallel
to the joist. The insulation should be cut to fit this space.
There are often both pipes and wires in crawlspace floors and occasionally
a junction box. Water pipes should be insulated and you will need to insulate
carefully around electrical wiring and boxes.
Insulation should be placed around cross braces by cutting it and pushing
it between the
Once the insulation is in place between the floor joists, insulation hangers
or nylon straps can be used to hold the product in place.
A 4- or 6-mil. polyethylene vapor retarder should be laid down to completely
cover the ground. Place rocks or bricks around the perimeter to hold it
1. For standard
wall heights, use pre-cut batts rather than continuous rolls. Each piece
of insulation is manufactured to the size of the most typical framing,
which usually is built either 16 or 24 inches on center and about 92 inches
high. These cut-to-size batts will make the job go faster and easier
2. The insulation should fit snug against the studs and completely fill
the cavity to the top and bottom plates. Cut batt insulation to fit snugly
around obstructions such as electrical boxes, plumbing and plumbing vent
3. When using kraft-faced batts with flanges, staple the flanges every
8 - 12 inches. The flanges can be stapled to the front or inside of the
stud. Drywall installers prefer the facing to be stapled on the inside
of the studs. Owens Corning PROPINK FastBatt Insulation does not
Note: Never leave faced insulation exposed. The facings on Kraft-and-foil-faced
insulation will burn and must be installed in substantial contact with
an approved ceiling, wall or construction material to help prevent the
spread of fire in the wall, ceiling or floor cavities. Unfaced fiber glass
In heating climates,
homes with subfloors of plywood or OSB sheathing generally will not need
a separate vapor retarder. But older homes with sub-floors made of wood
planking may need a separate vapor retarder. (In Gulf Coast and Florida,
local building practice may not call for any interior vapor retarder.)
If needed, simply cut strips of polyethylene the width of joists and staple
directly to underside of subfloor, or use kraft-faced insulation with
the paper up and in contact with the
Begin at one end of floor and place insulation between floor joists.
Insulation will stay in place temporarily if you are using R-19. R-25
insulation needs to be supported as you go. Use metal insulation supports
(16" or 24" wire rods or crisscrossed wire) to hold insulation
in place. Be careful not to compress insulation too much with supports.
Insulation should fit snugly against band joist and overlap bottom plate.
Measure and cut small pieces of unfaced insulation to fit snugly against
band joist. If the insulation is faced, peel off facing before installing
the small pieces. Where a wall vapor retarder is required, use a material
that meets local building codes (fire rated).
1. Lay temporary
flooring (using plank or plywood pieces) across joists and hang a temporary
work light. To make sure the eave vents aren't blocked, Owens Corning
Raft-R-Mate® attic vents or baffles should be installed to provide
2. Begin laying
faced fiber glass insulation at outer edge of attic and work toward center.
The vapor retarder should be facing down toward the warm-in-winter (living
area) side of the ceiling. In Gulf Coast states and Florida, local building
practice may not call for an interior vapor retarder.
3. Lay in long
runs first and use leftovers for shorter spaces. Ends of insulation should
be cut to fit snugly around cross bracing. Insulation should extend far
enough to cover exterior walls but should not block flow of air from eave
vents. If needed, install a baffle wherever there is an eave vent to assure
air flow. For additional
4. Insulation must be kept three inches away from recessed lighting fixtures
unless fixture is marked "I.C." (Insulated Ceiling) - designed
for direct insulation contact. The facing should be cut back so it is
not touching the light fixture. Insulation placed over an unrated fixture
may cause it to overheat and start a fire. The insulation should always
be installed at least three inches away from any metal chimneys, gas water
heater flues or other heat-producing devices.
5. Fill the spaces
between a masonry chimney and wood framing with a non-combustible material
such as unfaced fiber glass insulation, which will not burn
air ducts located in unconditioned spaces such as attics, crawl spaces,
garages, or unfinished basements can help improve your home's energy efficiency.
Air ducts supply conditioned air from your space heating and cooling equipment
to your living spaces. They also return an equal volume of air back to
the equipment to be conditioned again.
Ducts are typically made out of thin metal materials that easily conduct
heat. Therefore, uninsulated or poorly insulated ducts in unconditioned
spaces can lose through conduction 10%-30% of the energy used to heat
and cool your home. The heating and cooling equipment then has to compensate
for the heat loss and gain by conditioning additional air. This added
conditioning raises a homeowner's energy bills. In addition, when ducts
lose heat through conduction, rooms served by long duct runs can experience
"cold blow" during the winter because they usually have lower
Ducts in conditioned spaces experience minimal conductive losses and gains
since they are exposed to indoor air temperatures. However, these ducts
may also require some insulation to prevent condensation on duct walls
and to ensure that conditioned air is delivered at the desired temperature.
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