If you need to add insulation in your attic, save big by
blowing in cellulose insulation yourself. The pros
charge $1,500 to $2,000 to do a 1,200-sq.-ft. house.
You can do it yourself for about $500. Blowing attic insulation
isn’t hard, but it’s dusty, sweaty work. To make it easier,
grab a helper and set aside two days: one for attic prep
and the second to actually blow the insulation. By the end
of the weekend you’re going to be sore and tired. But saving
$1,000 or more will make up for your aching back.
The long-term payoff is impressive too. You could see
your energy bills go down by as much as 15 to 25 percent
depending on your climate and existing levels of insulation.
And you may also qualify for a tax credit on the cost of the
insulation (check with the IRS or at energystar.gov).
To show you how to do the job right, we asked our expert
to share his tips for making the job go smoothly and help you avoid the top three attic-insulation mistakes.
Our Insulation Expert
Arne Olson, the owner of Houle
Insulation in Minneapolis (houleinsulation.com), has insulated more than
5,000 homes. “A lot of those homes
were insulated by DIYers who didn’t
know what they were doing,” says
Olson. “They didn’t use enough insulation
and they didn’t seal up the
attic bypasses or put in vent chutes.”
Olson says it’s also common for
older insulation to settle over time.
“But you can blow cellulose over
whatever kind of insulation is already
there, and this is a great DIY project
for someone who doesn’t mind
working up a sweat.”
Seal attic bypasses
Leaks from cracks and gaps around
lights, plumbing pipes, chimneys,
walls and other ceiling penetrations are
the equivalent of having a 2-ft.-wide
hole in your ceiling. The worst offenders
are open stud and joist cavities and
dropped soffits and ceilings in kitchens
and baths (see Photo 1).
Install or repair vent chutes
“In 95 percent of the homes we work
on, the vent chutes are missing or
aren’t properly installed,” says Olson.
Without them, you’re not getting the
most out of your insulation’s R-value
because air needs to move properly at
the eaves to remove moisture in the
winter and heat in the summer.
To make sure existing chutes aren’t
blocked, stand in a dark attic to see
whether light from the eaves is filtering
through the vents. Replace any chutes
that are blocked, damaged or missing.
You’ll find both plastic and foam vent
chutes at home centers. Olson
recommends using foam chutes.
“They’re more rigid and there’s less
chance of them getting crumpled or
compressed when you’re installing
them.” Pull back the existing insulation
so you can see out to the edge of
the eaves, and install a vent chute in
every rafter space (Photo 2).
Dam and insulate the attic access
To keep the insulation from falling
through the attic hatch opening, make a
2x12 dam around the hatch perimeter.
“Then, to really seal the attic access up
tight,” says Olson, “lay fiberglass batt
insulation on the inside of the hatch or
door and wrap it up tight like a
Christmas present” (Photo 3). You can
insulate the hatch door while you’re
inside the attic or slide the door out
and do it more comfortably on a tarp
Mark your final insulation level
When you're blowing insulation, it can
get dusty and hard to see whether
you've got it deep enough around the
entire attic. Mark the desired level on
different roof trusses around the attic
before you start (Photo 4).
Pick up the blower and insulation
Cellulose insulation is a good choice
for DIYers. It has a higher R-rating and
is less expensive than either blown
fiberglass or fiberglass batts. It’s an
environmentally friendly material
made from recycled newspaper, so it’s
easier on your skin and lungs. And you
can blow it easily and quickly into odd-shaped
spaces in an attic, where access
is limited and dragging up batts is
Most home centers sell bagged cellulose
many provide the blower for a minimal
fee or free when you buy a certain
number of bags (usually 10 or more).
You can also rent the blowers from a
rental center. Although rental machines aren’t as
powerful as the truck-mounted units
the pros use, Olson says they work fine
for a DIYer.
To determine how many bags you’ll
need, measure your existing insulation
so you know your current R-value and
subtract that from the recommended
levels (see “Do You Need to Add
Insulation?” for how to find
recommended levels for your ZIP
code). Check the chart on the insulation
bag to determine the number of
bags necessary to reach your desired
R-value based on the square footage of
your attic. Olson recommends buying
more bags than you think you’ll need.
“You can always return them, and you
don’t want to stop in the middle of the
job because you’ve run out.”
Do You Need to Add Insulation?
The answer depends on where you live,
the heating and cooling costs in your
area, your existing insulation levels, local
codes and more. The first step is to make
sure you’ve sealed your attic bypasses.
Then visit www.eere.energy.gov and do
a search for “ZIP-Code Insulation
Program.” Use the insulation calculator
to plug in your ZIP code, lifestyle factors,
building design, energy costs and budget
to get a detailed recommendation.
The recommended insulation level for
most attics is R-38 (or about 12 to 15 in.
from the drywall, depending on the insulation
type). In the coldest climates,
insulating up to R-49 is recommended.
Set up the blower
The blower machine is heavy, so have
your partner along to help you load and
unload it. Set the blower on a tarp on
flat ground near the window or vent
opening closest to the attic access. Your helper will feed the insulation into the
hopper while you work the hose up in
the attic (Photo 5).
The blower should include two 50-ft.
hoses that you can connect and snake
into the attic. If your hoses have to
wind their way through the house to
reach a scuttle (the attic access) in a
hallway or closet, lay down tarps along
the way. It keeps things neater during
the process and makes cleanup a lot
Connect the hoses with the coupler
and then use duct tape over the coupler
to secure the connection. “Those metal
clamps can vibrate themselves loose,”
says Olson. “You don’t want them to
get disconnected and have cellulose sprayed all around your house.”
Back to Top
Blow the insulation
Wear eye protection, a long-sleeve shirt
and gloves, and a double-strap mask or
particulate respirator. Start as far away
from the access panel as possible and
blow the eaves and other tight spots
first. For hard-to-reach areas, duct tape
a length of PVC pipe to the end of the
blower hose. As you work back into
corners and around eave vents, don’t
cover any ventilating areas.
You can blow three rafter bays on
each side of the attic from one position.
Let the hose sit on the drywall to fill
the eave areas, giving it a shake to move
it from bay to bay. For the center areas,
hold the hose level and blow the insulation
evenly until you’ve reached your
level lines (Photo 6). Then pivot in place
and do the same thing to the other side.
Move across the attic until you’ve hit
your desired height at every point.
Blow the rest of the insulation until the
hopper is empty. You’ll end up with a
clean blower, and the extra inch or two
of insulation will settle over the next
The 3 Most Common DIY Insulation Mistakes
Mistake #1: Not sealing attic air leaks first
“No amount of insulation is going to help
if you don’t seal your attic properly,” says
Mistake #2: Not getting insulation out to the edges
“When you’re prepping the attic, use a
broom handle or stick to push the existing
insulation out to the edges. Then
when you blow in the cellulose, make
sure you do a good job of getting it way
over to the eaves with the hose.”
Mistake #3: Stepping through the ceiling
“It happens all the time,” says Olson. “You’ve got to
move around slowly and step from joist to joist.” If
there’s no floor, bring up a 12-in.-wide piece of 3/4-in.
plywood and lay it across the ceiling joists to use as a platform
to work from. And wear rubber-soled shoes so you can feel the joists
through the bottom of your feet.