In almost every way, the modern drywall-over-studs wall is better than its
timber-and-masonry and plaster-and-
lath ancestors. It’s fast and easy to
build, lightweight and makes the most
of inexpensive materials. But when it
comes to stopping sound, the modern
wall is a flop.
This article will show you how to
make these walls (and ceilings) block
sound better. The process involves
ripping the existing drywall off the
walls (and perhaps the ceiling), filling
the walls with fiberglass insulation,
attaching metal strips called “resilient
channel” to the studs, and fastening
new drywall to the channel.
This straightforward project
doesn’t require specialized tools or
high-level construction skills. Anyone
who has experience hanging and
taping drywall, along with a little
carpentry and electrical know-how,
can do this job.
Soundproofing is a messy, labor-intensive
project, however. To minimize household
havoc, it’s best to focus on one room, or at least
one room at a time. The room might be a place
that you want to keep sound out of—a home
office, for example. Or it may be a room you
want to keep sound in—like a home theater.
We won’t show you how to block noise
coming from outside since most exterior walls
already block sound fairly well. And any
improvement you make to them will be of
marginal benefit unless you also upgrade your
Resilient channel acts as a spring
between the drywall and studs.
When sound waves strike a wall built
with resilient channel, the drywall
can vibrate independently without
transferring the vibration to the
studs. The metal channel is available
at some home centers and all drywall
- Fiberglass insulation batts are
available at home centers. Although
“acoustic batts” are available, plain
old unfaced R-11 thermal insulation
works just as well. Don’t spend more
for R-13 batts; a higher R-value may
actually cut the STC rating slightly.
- Type X 5/8-in. drywall is available
at lumberyards and home centers. Type X
drywall is meant for fire-resistance,
but since it’s denser than standard
drywall, it also stops sound better,
especially when used with resilient
- Acoustical sealant is available at
drywall suppliers, but
silicone caulk found
at home centers is
also a good choice.
With either type,
you’ll need lots of it
and will probably
save a few bucks by
buying a big caulking
gun that uses the
- For attaching
the channel to
studs, use 1-1/4 in.
screws. For attaching
drywall to channel, use 1-in. screws. Fine-threaded
screws grab on to resilient channel
better than the coarse-threaded
- Door gaskets, door sweeps and
transition strips are available at
Before you tackle this project
The sound-stopping methods covered in this
article have proved themselves over decades of
laboratory testing and real-world use. But
they’re the sound-control equivalent of major
surgery, and you should consider two other
options before you go ahead:
1. Deal with the source of the sound.
Listen to the noises you want to block out. If
footsteps on the floor above you sound like
hammer blows, consider carpet instead of
notoriously noisy coverings like wood or tile.
Think about replacing old groaning appliances.
Does the TV or stereo really have to be
so loud or do you turn it up just out of habit?
Limiting noise at the source is sometimes
cheap and easy (moving tuba practice into the
basement), sometimes troublesome and
expensive (replacing the dishwasher). But it’s
the least complicated and most effective
2. Make rooms as airtight as possible.
Like air, sound passes through the smallest
cracks and holes. Think of the way sound
comes past a door that’s cracked open just
a fraction of an inch: Close the door, and the sound is noticeably
quieter. All the tiny, often invisible pathways
through a typical wall or floor add up to a
gap larger than the one along that cracked-open
door. Electrical boxes are major offenders.
Remove outlets, switches and fixtures from
their boxes (turn off the power first), and seal
the holes inside the boxes with silicone caulk.
Also caulk the gaps between the boxes and drywall.
Add gaskets and sweeps to doors (Photos
9 through 11). You might even remove base boards to seal the gap between the
drywall and the floor (Photo 8). We
strongly recommend trying this
approach before tearing up your
walls. It’s low-cost, low-hassle and
effective—and if you don’t get the
results you want, you haven’t wasted
much time or money.
“Sound transmission class” ratings
indicate a wall’s (or floor’s) ability to
block sound. STC ratings are determined
in a laboratory under ideal
conditions. There are all kinds of variables
in the real world that STC ratings
don’t take into account. (These
include walls that contain plumbing
lines and sound traveling around
walls, through ducts and via other
pathways.) Still, STC ratings are useful
for comparing sound control
methods and materials.
A typical wall made from 2x4 studs
and covered with 1/2-in. drywall on
both sides carries an STC rating of 34.
You’d be able to hear, and partially
understand, a loud conversation taking
place on the other side of this
standard wall. Put fiberglass insulation
in this wall and its rating rises to
39. You’d still hear the voices on the
other side, but they’d be muffled and
unintelligible. Cover one side of the
insulated wall with resilient channel
and 5/8-in. drywall and the STC
jumps to about 50. At this point you
wouldn’t hear the conversation at
all—unless they started shouting.
We chose this last wall combination
(insulation, resilient channel,
5/8-in. drywall) as a good compromise
between cost and effectiveness.
But you can go further. For example,
by attaching resilient channel to one
side of the insulated wall and screwing
on four layers of 1/2-in. drywall (two
on both sides), you’ll get an STC of
How to soundproof an existing wall
Add Soundproofing to a Wall Without Demolishing It
Cut holes at the top of each stud cavity
and blow cellulose insulation into the
cavities. Cut new 5/8-in. drywall so it’s
1/4 in. short of the floor and ceiling.
Then attach the new drywall sheets
using special acoustical dampening
adhesive and drywall screws. Caulk the
gaps with acoustical caulk.
Whisper clips and headrails
Alternative Attachment: “Whisper Clips” and “Headrails”
“Whisper Clips” and “headrails” (a metal firring strip similar to resilient channel) are an alternative to resilient channel with screws.
Attach the whisper clips in a
staggered fashion to the studs and clip on the
headrails. Attach 5/8-in.
drywall to the rails, leaving a
1/4-in. gap along the top
and bottom. Fill the gaps
with acoustical caulk. For
extra soundproofing, add a
second layer of drywall, staggering the seams.
The metal ducts of a forced-air heating/
cooling system are a noise
fighter’s archenemy. They not only
punch large holes in a room but also
carry sound throughout a house. If
there are metal ducts connected to the
room you want quieted, listen to the
sounds entering the room. If they’re
primarily coming through the ducts,
this insulation/resilient channel project
won’t help, no matter how soundproof
you make the walls. And unfortunately,
there’s not much you can do
about metal ducts, short of lining
them with fiberglass or replacing
them with fiberglass ducts (large,
often impractical projects).
The best way to keep sound from
passing through a floor or ceiling into
the room above or below is to use insulation and resilient channel. Ripping
drywall off a ceiling in a room
where you’re stripping the walls anyway
isn’t such a big deal. But if you
want to keep sound from traveling
through the floor of a room, you have
to tear out the ceiling in the room
below or buy an
acoustical floor covering. The good thing about stripping
a ceiling is that you can block off
spaces between joists.
NOTE: If the sound coming through
your ceiling is primarily “impact
noise” (such as footsteps or toys slamming
against the floor), the best fix is a
heavy carpet and pad.
A typical wood-panel or hollowcore
door has an STC rating of
about 17. By sealing between the
jamb and wall framing, and adding
weatherstripping gaskets and a door
sweep (Photos 9 through 11), you
can raise the STC to 20; that’s an
easy, noticeable improvement, but
maybe not enough.
A sound barrier is only as good as
its weakest point. So if you go to the
trouble of building a 50-STC wall
with a 20-STC door, most of the
benefit will be lost through the door.
Keep this in mind when you decide
whether or not to add insulation
and sound channel to a wall with a
To reach an STC rating higher
than 20, you have to replace your
door and jamb. A well-sealed solidcore
wood door has an STC of about
28. “Acoustical” wood doors with
STCs in the 30-to-50 range are also
available. Most lumberyards stock or can order interior
solid-core doors, but for
acoustical doors, your best bet is a
supplier that caters to commercial
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What to do, what not to do
Here are some rules of thumb for
- Caulk like crazy. Your goal is an airtight
room. Caulk around electrical
boxes, light fixtures, and plumbing
and heating lines. Seal up even the
smallest holes and cracks. Remember,
if air can pass through, so can sound.
- If you have old plaster-and-lath
walls, don’t remove them to add insulation
and resilient channel. Plaster-and-
lath walls are good sound-stoppers.
To improve them, just seal
cracks and gaps.
- Removing ceiling drywall gives you a great opportunity to add light fixtures.
If you choose recessed lights,
buy those rated “IC” so you can surround
them with insulation. Other
recessed fixtures must not come in
contact with insulation.
- You must remove existing drywall
before installing resilient channel.
Don’t simply attach the channel
over existing drywall.
- If you go to the trouble of tearing
off drywall, don’t cheat yourself by
using resilient channel or insulation
alone. Use them together and you’ll
gain up to 15 STC points. But use
either one alone and you’ll gain only
four or five.
- Don’t bother attaching resilient
channel to both sides of a wall. One
side does the job.
- Don’t use resilient channel on steel
studs. Steel studs absorb vibration by
themselves, so there’s no need to use
sound channel. A steel-stud wall with
insulation alone performs about the
same as a wood-framed wall with
insulation and resilient channel.