A typical family spends about a third of its annual heating and
cooling budget—roughly $350—on air that leaks into or out of the house
through unintended gaps and cracks. With the money you waste in just
one year, you can plug many of those leaks yourself. It’s among the
most cost-effective things you can do to conserve energy and increase
comfort, according to Energy Star. Start in the attic, since that’s
where you’ll find some of the biggest energy drains. Then tackle the
basement, to prevent cold air that enters there from being sucked into
upstairs rooms. Finally, seal air leaks in the rest of the house. Here
are eight places to start.
1. Insulate around recessed lights
Most recessed lights have vents that open into the attic, a direct
route for heated or cooled air to escape. When you consider that many
homes have 30 or 40 of these fixtures, it’s easy to see why
researchers at the Pennsylvania Housing Research/Resource Center
pinpointed them as a leading cause of household air leaks. Lights
labeled ICAT, for “insulation contact and air tight,” are already
sealed; look for the label next to the bulb. If you don’t see it,
assume yours leaks. An airtight baffle ($8-$30 at the home center) is
a quick fix. Remove the bulb, push the baffle up into the housing,
then replace the bulb.
2. Plug open stud cavities
Most of your house probably has an inner skin of drywall or plaster
between living space and unheated areas. But builders in the past
often skipped this cover behind knee walls (partial-height walls where
the roof angles down into the top floor), above dropped ceilings or
soffits, and above angled ceilings over stairs.
Up in the attic, you may need to push insulation away to see if the
stud cavities are open. If they are, seal them with unfaced fiberglass
insulation ($1.30 a square foot) stuffed into plastic garbage bags;
the bag is key to blocking air flow. Close large gaps with scraps of
drywall or pieces of reflective foil insulation ($2 a square foot).
Once you’ve covered the openings, smooth the insulation back into
place. To see these repairs in action, consult Energy Star’s DIY guide
to air sealing.
3. Close gaps around flues and chimneys
Building codes require that wood framing be kept at least one inch
from metal flues and two inches from brick chimneys. But that creates
gaps where air can flow through. Cover the gaps with aluminum flashing
($12) cut to fit and sealed into place with high-temperature silicone
caulk ($20). To keep insulation away from the hot flue pipe, form a
barrier by wrapping a cylinder of flashing around the flue, leaving a
one-inch space in between. To maintain the spacing, cut and bend a
series of inch-deep tabs in the cylinder’s top and bottom edges.
4. Weatherstrip the attic access door
A quarter-inch gap around pull-down attic stairs or an attic hatch
lets through the same amount of air as a bedroom heating duct. Seal it
by caulking between the stair frame and the rough opening, or by
installing foam weatherstripping around the perimeter of the hatch
opening. Or you can buy a pre-insulated hatch cover kit, such as the
Energy Guardian from ESS Energy Products ($150).
5. Squirt foam in the medium-size gaps
Once the biggest attic gaps are plugged, move on to the medium-size
ones. Low-expansion polyurethane foam in a can is great for plugging
openings 1/4-inch to three inches wide, such as those around plumbing
pipes and vents. A standard 12-ounce can ($5) is good for 250 feet of
bead about half an inch thick. The plastic straw applicator seals shut
within two hours of the first use, so to get the most mileage out of a
can, squirt a lubricant such as WD-40 onto a pipe cleaner and stuff
that into the applicator tube between uses.
6. Caulk the skinny gaps
Caulk makes the best gap-filler for openings less than 1/4-inch wide,
such as those cut around electrical boxes. Silicone costs the most ($8
a tube) but works better next to nonporous materials, such as metal
flashing, or where there are temperature extremes, as in attics.
Acrylic latex caulk ($2 a tube) is less messy to work with and cleans
up with water.
7. Plug gaps in the basement
Gaps low on a foundation wall matter if you’re trying to fix a wet
basement, but only those above the outside soil level let air in. Seal
those with the same materials you’d use in an attic: caulk for gaps up
to 1/4-inch wide and spray foam for wider ones. Use high-temperature
caulk around vent pipes that get hot, such as those for the furnace or
water heater. Shoot foam around wider holes for wires, pipes, and
ducts that pass through basement walls to the outside.
In most older houses with basements, air seeps in where the house
framing sits on the foundation. Spread a bead of caulk between the
foundation and the sill plate (the wood immediately above the
foundation), and along the top and bottom edges of the rim joist (the
piece that sits atop the sill plate).
8. Tighten up around windows and doors
In the main living areas of your home, the most significant drafts
tend to occur around windows and doors. If you have old windows,
caulking and adding new weatherstripping goes a long way toward
tightening them up. Bronze weatherstripping ($12 for 17 feet) lasts
for decades but is time-consuming to install, while some self-stick
plastic types are easy to put on but don’t last very long.
Adhesive-backed EPDM rubber ($8 for 10 feet) is a good compromise,
rated to last at least 10 years. Nifty gadgets called pulley seals ($9
a pair) block air from streaming though the holes where cords
disappear into the frames.
Weatherstripping also works wonders on doors. If a draft comes in at
the bottom, install a new door sweep ($9).
Before working in the attic, take some precautions
Try to do attic work on a cool day. Wear protective gear: disposable
clothes, gloves, and a double-elastic mask or half-face respirator.
Bring along a droplight with a fluorescent bulb, plus at least two
pieces of plywood big enough to span two or three joists to support
you as you work. To save trips up and down a ladder, try to move up
all of the materials you need before you get started. One warning: If
you find vermiculite insulation, hold off until you’ve had it checked
for asbestos; your health department or air-quality agency can
recommend a lab.