such as plywood, particleboard, and OSB may
just have surface mold, so probe them with an ice
pick or pocketknife to see how sound they are. If
they are spongy, replace them. Engineered wood
products are particularly susceptible to rot
because they contain adhesive binders that fungi
feed on.
Remediation. Wash surface mold with soap and
water and let it dry well. There’s no need for
caustic bleaches to kill mold spores (and irritate
your lungs) because washing should remove
mold. After the surface has dried, paint it with a
stain killer such as B-I-N®. If mold has caused
the drywall’s paper facing to roughen or delami-
nate, cut back the drywall at least 1 ft. beyond the
damaged area and replace it.
If your inspection revealed mold growing
inside wall cavities, use sheet plastic to seal off
the affected area, including the heating registers,
Whether they’re removing asbestos or mold-contaminated
then cut back damaged drywall to the nearest
drywall and framing, pros dress for the job. Here,
stud center on both sides, and cut out damaged
protective clothing includes a respirator mask with N95
framing, if any. If you must replace more than
filters, gloves, boot covers, and disposable Tyvek coveralls
one stud, erect temporary shoring to support the
and hood. Duct tape seals the coveralls at the wrists
and ankles.
loads above (see chapter 10). To contain spore-
laden dust, have a helper hold the hose of the
commercial-grade HEPA vacuum near the mate-
rials being cut. Using soapy water, scrub the sur-
the end of each day. After assessing the mold’s
face mold from the framing, and allow all materi-
extent, determine the shortest way out of the
als to dry well before installing new drywall—
house for contaminated materials—maybe out a
framing moisture content should be 15% to 20%
window—to minimize spreading mold spores to
or less. (Borrow or buy a moisture meter to
clean areas. Use sheet plastic to seal doorways
check.) Wrap moldy debris in 6-mil plastic and
and heating registers in affected areas, and turn
have it carted away.
off HVAC systems until the remedial work is
complete. Seal damaged materials in plastic
Choosing Insulation Wisely
before transporting them from the site. Never
sand moldy materials because that will spread
There are dozens of insulating products, which
spores. Finally, rent a commercial-grade
I’ll classify into five groups: (1) batts (precut
vacuum with HEPA filters; if possible, vent
lengths or continuous rolls), (2) loose fill (blown
it to the outside.
into open spaces) (3) dense pack (blown into
confined spaces), (4) rigid-foam panels, and
Assessing the extent. If mold is limited to small (5) spray foam.
areas at the top of a bathroom or exterior wall, it
may be surface mold caused by condensation or
BATT InSulATIon
inadequate ventilation. However, if mold is wide-
spread around windows or doors, bathroom dry-
Batts may be made of fiberglass, mineral wool,
wall is crumbling, or tiles mounted on drywall
or recycled cotton, but fiberglass batts are by far
are loose, there’s probably mold growing in the
the industry leader, accounting for three-quarters
walls. Start looking at the base of the walls. Turn
of residential insulation sales. Inexpensive and
off the electrical power to the area, remove the
easy to install, batts are favored by DIYers. Faced
baseboard, and use a utility knife or a hole saw
with kraft paper or foil, batts may be stapled to
to cut small holes in the drywall. If there’s no
the face or edges of studs, joists, or rafters;
mold, you can easily patch the holes and cover
unfaced batts are friction-fitted between framing.
them with the baseboard. More likely, you’ll
In unfinished attics, unfaced batts are placed
Energy Conservation and Air Quality
405
between floor joists or atop existing batts to
proof to a degree, and insulate well. Made from
improve heat retention.
recycled cotton, batts are treated with a natural
However, for batt insulation to meet the
biostat (borate) to inhibit mold and make them
R-values claimed by manufacturers, batts must
fire-resistant. Wear a disposable paper mask
be installed precisely so they fill cavities between
when installing cotton: Although its lint is more
framing members without gaps or thin spots.
benign than airborne glass fibers, avoid breath-
One problem is that framing in old houses is fre-
ing it anyway.
quently irregular, so batts with precut widths
mineral wool (also called rock wool) is spun
often don’t fit well. Consequently, if installers
from natural stone such as basalt or made from
don’t fill gaps, cut batts a bit short, allow facing
metal oxides and is the most fire-resistant of any
flanges to pucker, or don’t take time to fit insula-
insulation. Rock wool, used to insulate wall cavi-
tion behind pipes and electrical cables, air move-
ties early on, is now enjoying a revival among
ment can dramatically reduce their R-value. This green builders. Relatively dense, it insulates and
is especially true for batts made of fiberglass
soundproofs pretty well. Wear a respirator and
because fiberglass is less dense than most other
gloves when working with it, for it has health-
P R O T I P
insulating materials.
related concerns similar to those of fiberglass.
Fiberglass batts. Because it is such a big seller,
Standard fiberglass can itch
fiberglass makers are constantly reworking the
looSE-FIll InSulATIon
like crazy. So even if you wear a
long-sleeved shirt and a pair of
stuff. Fiberglass is famously itchy, of course. So
Usually cellulose or fiberglass, loose-fill insula-
gloves, wash well at the end of
in response to eye, skin, and lung irritation
tion is most often used to retrofit unfinished
each day with cold water. Exactly
caused by loose glass fibers, makers now offer
attics. Loose fill can be blown in quickly, does a
why cold water reduces itching is
batts encapsulated in perforated or woven plastic great job of filling irregular and hard-to-reach
unclear (shrinks pores perhaps),
wrapping—which you can carry bare-handed and spaces, and outperforms batt insulation. It’s also
but it works.
install overhead without fibers raining down on
something a homeowner can install. Smaller
you. In some products, the fiberglass has been
blowers can be rented at most home centers,
reformulated so that it’s soft, itchless, and form-
along with a 2-in.- or 3-in.-diameter hose and the
aldehyde free. There are also fiberglass batts of
bales of insulation that one worker feeds into the
varying density: 31⁄2-in.-thick batts that are rated
blower hopper, while the other worker sprays the
at R-11, R-13, and R-15; and 51⁄2-in.-thick batts
loose-fill insulation. The more inches of loose fill
rated at R-21. Note: If you compress batts into
the cavities, you decrease the insulation’s loft and
thus reduce its R-value slightly.
cotton batts (often called blue jean insulation)
are formaldehyde-free and itchless. Because of
their density, they slow air movement, sound-
Precut fiberglass batts are by far the
most commonly installed insulation.
Always read labeling before opening
to be sure the batts inside are of the
correct length, width, thickness, and
R-value for the task at hand.
The explosion of new insulating materials includes
these itch-free, environmentally friendly cotton batts,
also called blue-jean insulation, which are created
from mill wastes.
406 Chapter 14
Recommended levels of Insulation
Insulation levels are specified by R-value. R-value is a measure of insulation’s ability to resist heat traveling
through it. The higher the R-value, the better the thermal performance of the insulation. The table below shows what
levels of insulation are cost-effective for different climates and locations in the home.
Uninsulated wood-frame wall:
drill holes in the sheathing and blow insulation into the empty wall cavity before installing the new siding, and:
Zones 3 to 4: Add R-5 insulative wall sheathing beneath the new siding.
Zones 5 to 8: Add R-5 to R-6 insulative wall sheathing beneath the new siding.
Recommended Levels of Insulation
Insulated wood-fr
Insulation lev
ame wall:
els are specified by R-value. R-value is a measure of insulation's ability to resist heat traveling through it.
Zones 4 to 8: Add R-5
The higher the R-v insulative sheathing befor
alue the better the ther e installin
mal perf g th
or e new siding.
mance of the insulation. The table below shows what levels of
insulation are cost-effective for the different climates and locations in the home
Map courtesy of the department of Energy, www.energystar.gov
7
6
7
4
5
6
6
5
5
5
4
3
3
3
2
2
All of Alaska is in Zone 7 except
the following Boroughs in Zone 8:
2
Bethel
northwest Arctic
Zone 1 includes:
dellingham
Southeast Fairbanks
Hawaii
Fairbanks n. Star wade Hampton
Guam
1
nome
yukon-koyukuk
puerto Rico
north Slope
Virgin Islands
Zone
Added Insulation to Attic
Floor
ADD INSUlATION TO ATTIC
Uninsulated Attic
Existing 3-4 inches of Insulation
1
R30 to R49
R25 to R30
`
R13
Zone
Uninsulated Attic
Existing 3–4 Inches of Insulation
Floor
2
R30 to R60
R25 to R38
R13 to R19
1 3
R30 to R60
R30 to R49
R25 to R38
R25 t o R30
R19 to R25
R13
4
R38 to R60
R38
R25 to R30
2
R30 to R60
R25 to R38
R13 to R19
5-8
R49 to R60
R38 to R49
R25 to R30
3
R30 to R60
R25 to R38
R19 to R25
4
R38 to R60
R38
R25 to R30
5 to 8
R49 to R60
R38 to R49
R25 to R30
Energy Conservation and Air Quality
407
you install, the higher the R-value you’ll achieve.
loose-fill cellulose is mostly recycled newspa-
Depths of 12 in. to 18 in. are fairly common.
pers, ground up and treated with borate to make
Note: Prepping the space is important, so see
it fire- and mold-resistant. Denser than fiber-
the earlier section on air-sealing an attic. You’ll
glass, it is less air-permeable and averages
want to cover any large hole such as chases, keep R-values of 3.2 per in.; to attain an R-49 rating,
loose-fill insulation 2 in. away from the chimney,
you’d need to blow in about 15 in. of loose-fill
and install some kind of baffle to prevent loose
cellulose. Its lower cost, higher R-value, and
fill from blocking soffit vents.
lower tendency to irritate skin give cellulose a
slight edge over fiberglass. Cellulose’s major
loose-fill fiberglass has fluffy, spun-glass fibers downside is that it absorbs water and dries slow-
and an R-value of 2 to 2.7 per in.; to attain an
ly. Were there a major leak, that retained water
R-49 rating on an attic floor, you’d need to blow
could soak the drywall ceiling below.
in a thickness of approximately 19 in. Not as
Spray polyurethane foam is rarely used to insu-
dense as cellulose, it is more air-permeable.
late attic floors because it’s prohibitively expen-
Researchers report that in temperatures below
sive. But it is occasionally used as a thin flash
0°F, convection currents passing through loose-
coat to air-seal an attic after it’s been prepped.
fill fiberglass can reduce its effectiveness by 30%. The foam is then covered with loose-fill fiberglass
In the event of a minor roof leak, fiberglass will
or cellulose until the desired R-value is achieved.
probably dry quickly; being inorganic, it is also
mold-resistant. Loose-fill fiberglass is slightly
dEnSE-pACk InSulATIon
more expensive than cellulose.
Dense-pack insulation uses the same bales of cel-
lulose or fiberglass as loose-fill installations,
except that the materials are blown into confined
spaces at higher pressures—say, 3 lb./cu. ft.—by
Insulation Values more powerful blowers. Dense-pack insulation
TYPE OF
R-VAlUE
should be installed only by trained specialists. It
INSUlATION
PER INCH
is not a job for DIYers.
In renovations where interior surfaces have
Batts and blankets
been gutted (or in new construction), the insula-
Fiberglass
3.2
tion is confined by a polymer mesh netting
&nbs
p; stretched taut across studs or rafters, then glued
Cotton
3.5
or stapled to framing edges so it stays put. The
Mineral wool
3.2
installer slits small holes in the netting, inserts
the nozzle of the blower hose, and fills each bay.
loose fill
It takes skill. If too much insulation is blown in,
the netting may bulge so much that drywall can’t
Fiberglass
2.2–2.7
be installed over it.
Cel ulose
3.2
More often, renovators use dense-pack insula-
tion when they want to increase the R-value of
Dense pack (3 lb./cu. ft.)
walls while leaving interior finish surfaces intact.
They gain access to wall cavities by removing
Fiberglass
2.5–3.5
small sections of siding, drilling holes through
Cel ulose
3.8
exterior sheathing, and blowing in insulation
(usually cellulose) until each cavity is filled. Here
Rigid-foam panels
again, it takes skill. A seasoned installer can tell
by the whine of the blower when the correct den-
Expanded polystyrene (EpS)
4.0
sity is achieved. How long it takes to fill a stud
Extruded polystyrene (XpS)
5.0
bay is also telling. If a bay fills too quickly, fire-
stops may be blocking part of a bay; if a bay takes
polyisocyanurate
6.5
forever to fill, it may be open at the bottom and
insulation is billowing into the crawlspace. As
Spray-on (contractor applied)
with any installation, it’s important to survey and
Closed-cel polyurethane
6.5
prep the structure to avoid such problems. An
open-cel polyurethane
3.6
energy auditor’s thermal image of cold spots can
also help an installer insulate around obstruc-
Magnesium oxide
3.8
tions in a wall.
408 Chapter 14
At low densities (1.5 lb./cu. ft.), cellulose traps
Note: Installing rigid-foam insulation over
air and is an effective insulator (R-3.5/in.). When
Renovation 4th Edition Page 95