| SOUNDPROOFING
WALLS/CEILINGS USING RESILIENT CHANNEL AND ACOUSTICAL MAT
TO MAKE A SOUND DEADENING WALL (or Ceiling). |
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PRINTER FRIENDLY VERSION |
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| The partition walls in most family homes are constructed of
Drywall (Sheetrock/Gypsum Board) firmly attached to both sides of a wood or
metal stud frame. When sound waves hit one side of the wall it causes the
drywall on that side to vibrate. Since the drywall is rigidly connected to
the stud frame, the vibration is transmitted right through the studwork to
the drywall on the other side and re-radiated. Those same vibrations traveling through the
studwork can also duct noise throughout adjacent floors and ceilings. Noise
will radiate easily through the structure because there’s almost nothing
there to isolate or absorb the sound waves.
To reduce this effect and to dampen the sound waves, resilient metal
channels can be inserted between one of the drywall walls and the studwork.
The resilient channels act as shock absorbers, greatly reducing vibrations
coming from either side of the wall from passing through the wall. Absorbent
mat is used inside the wall to cushion the channel/drywall and to provide an
absorbent compartment to trap sound waves.
The resilient channel technique by itself typically adds 3 to 5 (or more)
Sound Transmission Class (STC) points to an otherwise identical wall or
ceiling. This by itself, is not usually sufficient to meet total noise level
reduction requirements under most circumstances. Other added construction
materials and techniques are usually needed, such as adding absorbent mat
and/or barrier material to the wall space. Some considerations are the
amount of wall space that can be donated as mounting the wallboard on these
1/2" thick channels increases the thickness of the wall (or ceiling)
somewhat.
It is important to distinguish acoustically effective resilient channels
from hat channels, Z-channels and other lightweight metal furring systems
that drywall contractors are used to installing. These other systems may
resemble resilient channels, but they allow no movement and are simply too
rigid to be effective. Only true resilient channels have any acoustical
benefit.
It is extremely important to install these channels correctly. Improper
installation will nullify any advantage gained from using it in the first
place.
There are a few simple procedures that need to be followed when using
them. In existing walls, large opening should be cut in the drywall panels
to “Open Up” the wall and expose the dead air to the new wall covering. One
large dead air space that is created and linked together contributes greatly
to the sound control system. In fact, adding furring strips (spacing
blocks) of 1"-2" increases the sound reduction effect (especially at low
frequencies of sound) by increasing the dead airspace. The channels are then
applied directly over Super Soundproofing MLV barrier mat that should be
first used to cover the wall. The new drywall panels are then coated with
absorbent closed cell matting material to create an absorbent compartment to
dampen sound waves. The absorbent mat is applied like wallpaper using
contact cement and a roller. The thickness of material used depends on the
level of sound control desired: More is better! In an open, studded wall,
sound barrier material (MLV) is typically stapled to the studs, but for best
results, between a layer of soundboard and drywall attached to the channels,
even though it can be cut and weaved between the studding. On walls and
ceilings, the channel should be mounted at a right angle to the framing. On
walls, mount with the narrow flange along the bottom and the larger flange
up. This allows the drywall’s weight to draw itself away from the framing.
Make sure all the flanges should are pointing in the same direction.
When fastening the drywall to the channels, the
mounting screws are to be driven into the channels in-between the studs or
joists. It is absolutely critical not to "short out" the resilient channels
by screwing long screws into the studs behind them. This rigid connection
would destroy their benefit of “Floating” the wall or ceiling assembly.
The resilient channels should be held back from intersecting surfaces
about ¼" on the side edges, and about 4-6" from the top and bottom of the
wall.
It does little good to carefully attach the channels in the middle of the
wall if one installs baseboard screws that may connect the entire bottom
edge to sill plates. Similarly, it is easy to "short out" the resilient
channels at the top of the wall by screwing into headers. Leave space where
the wallboard is not connected. The drywall attached to the channels also
needs to be held back about ¼" from similar intersecting corners. If the
drywall panel edges are jammed against wall or ceiling panels, then they
will tend to be rendered ineffective. For walls, the drywall edges should be
resting on neoprene vibration pads and sealed with caulk before the wall is
finish taped and painted. This provides a supporting base on which to mount
the wall and “Unload” the channels from the weight of the drywall panels.
Use 2 of the 2" pads per vertical sheet of drywall or, 1 every 2' or so..
The weight of the drywall will tend to crush the drywall edge down on the
pad, narrowing the gap to the floor to be sealed. The gaps should then be
sealed, as air-tight as physically possible, with plenty of flexible
non-hardening caulk. "Backer Square” or Lead tape can also be used for this.
When the
resilient channels are properly installed, it should be possible to push and
slightly flex the wall or ceiling surface. A lack of flex indicates that the
channels too rigid, perhaps because they are shorted out by too long of
screws fastened into the wood framing. Also, it usually does not matter
which side of the wall is resiliently hung. Of course, doing both sides of
the wall is better. For ceilings, use RC-2, which is simply two-legged RC-1.
If not readily available, RC-1 can be used but more of it is needed. |
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| To reduce this effect and to dampen the sound
waves, resilient metal channels can be inserted between one of the drywall
walls and the studwork. The resilient channels acts as shock absorbers,
greatly reducing vibrations coming from either side of the wall from passing
through the wall. Absorbent mat is used to cushion the channel/drywall and
to provide an absorbent compartment to trap sound waves. |
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| The resilient channel technique by itself
typically adds 3 to 5 Sound Transmission Class (STC) points to an otherwise
identical wall or ceiling. This by itself, is not usually sufficient to meet
total noise level reduction requirements under most circumstances. Other
added construction materials and techniques are usually needed, such as
adding absorbent mat and/or barrier material to the wall space. Some
considerations are the amount of wall space that can be donated as mounting
the wallboard on 1/2" channels increases the thickness of the wall (or
ceiling) somewhat. |
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| It is important to distinguish acoustically
effective resilient channels from hat channels, z-channels, and other
lightweight metal furring systems that drywall contractors are used to
installing. These other systems may resemble resilient channels, but they
allow no movement and are simply too rigid to be effective. Only true
resilient channels have any acoustical benefit. A diagram of a typical
channel is shown below. |
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| It is extremely important to install these
channels correctly. Improper installation will nullify any advantage gained
from using it in the first place. |
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| There are a few simple procedures that need
to be followed when using them. On walls and ceilings, the channel should be
mounted at a right angle to the framing. On walls, mount with the narrow
flange along the bottom and the larger flange up. This allows the drywall’s
weight to draw itself away from the framing. Also, the flanges should all be
pointing in the same direction. |
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| When fastening the drywall, the screws are to
be connected to the channels in-between the studs or joists. It is
absolutely critical not to "short out" the resilient channels by screwing
long screws into the wood studs behind them. This rigid connection would
destroy their benefit. In existing walls, the channels are applied directly
over Super Soundproofing acoustical mat
that should be used to cover the wall first. The absorbent, closed dead air
space that is created contributes greatly to the sound control system. In
fact, adding furring strips (spacing blocks) of 1"-2" increases the sound
reduction effect by increasing the dead airspace. The
absorbent mat is applied like wallpaper
using contact cement and a roller. The thickness of material used depends on
the level of sound control desired: More is better! Sound
Barrier material (MLV) is typically stapled to the studs or over the wall. In
an open, studded wall, the mat is applied over the studs but for best
results, between a layer of sound deadening board and drywall, even though it can
be cut and fitted between the studding. Then tape off and paint the
sound deadening wall. |
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| The resilient channels should be held back
from intersecting surfaces about ¼" on the side edges, and about 4-6" at the
top and bottom of the wall. It does little good to carefully attach the
channels in the middle of the wall if one installs baseboard screws that may
connect the entire bottom edge to sill plates. Similarly, it is easy to
"short out" the resilient channels at the top of the wall by screwing into
headers. Leave space where the wallboard is not connected. The drywall
attached to the channels also needs to be held back about ¼" from similar
intersecting corners. If the drywall panels are jammed against the edges,
then they will tend to be rendered ineffective. For sound deadening walls, the drywall
should best be resting on neoprene
vibration pads and sealed with caulk before the wall is finish taped and
painted. This provides a resilient base on which to mount the wall and
better close the gap at the bottom of the wall. Use 2 of the 2" pads per
vertical sheet of drywall or, 1 every 2' or so.. The weight of the
drywall will tend to crush the drywall edge down on the pad, narrowing the
gap to the floor to be sealed. The gaps should then be sealed, as
air-tight as physically possible, with plenty of flexible non-hardening
acoustical caulk.
"Backer Square" or Lead tape can also be used for this. |
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| When the resilient channels are properly
installed, it should be possible to slightly flex the wall or ceiling
surface. A lack of flex indicates that the channels too rigid, perhaps
because they are shorted out by too long of screws fastened into the wood
framing. Also, it usually does not matter which side of the wall is
resiliently hung. Of course, doing both sides of the wall is better.
For ceilings, use RC-2, which is simply two-legged RC-1. If not readily
available, RC-1 can be used but more of it is needed. |
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<Old Method
New Method>
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Resilient Channels and
"Soundboard" |
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| Sound deadening board is a
material made from compressed wood fibers. Another similar trade name is "Homasote" ( Somewhat
better, but considerably more expensive) and it functions as a thick paper
cushion.
"Celotex" also makes a version. It used to be that the theory was that soundboard would provide basic
resilient isolation for the drywall layers over it. However, screws or nails
breach the system and reduce the isolation to the point where, acoustically
speaking, it would be better to replace the screws with construction
adhesive as much as possible. When using resilient channel and double
layers, use extra care to screw the drywall mostly into
the soundboard and not through to the metal channels and not to touch studs
underneath. The benefit is that the different physical acoustical properties
of the drywall and soundboard complement each other, improving sound
reduction qualities. Mass loaded barrier is appropriately used between
the soundboard and drywall for many added STC points. A construction adhesive like
"Liquid Nails" may be used to attach it, but staples work better.. |
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DESCRIPTION: |
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| WHAT IT IS! |
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 (Note
the large flange is up)
DWFC (DryWall Furring Channel)
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| Resilient channel is a thin metal channel
designed to substantially improve the sound insulation of drywall, sheetrock
and plasterboard walls and ceilings. The channel effectively isolates the
drywall from the framing studwork, reducing ‘direct contact’ to help
dissipate sound which would normally be directly transferred through the
frame. This system is easy to install and produces dramatic results. The
channels measure about 1/2" in thickness and the wide flange (drywall mount)
is about a 1 1/4" wide. The vibration absorption properties of the
channel can be additionally enhanced by applying thin (1/8")
"Super Soundproofing Absorbent Tape" to the flange of the drywall mount.
If not using the RC channel alone or Sound Clips and DWFC, at least use the tape on the face
of the studs. |
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| Example: |
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| A standard metal framed stud partition lined
both sides with ½" drywall with fiberglass insulation in the wall cavity,
(Note: "Packing" in the insulation many may think increases the thermal
properties, but it will definitely decrease sound reduction), gives an
STC rating of around 20-25 or less. |
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| Conversation can be heard).
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| The same wall, but with just resilient
channel between the drywall and frame, to one side only, can increase the
rating to as high as a STC rating of 35 or so.
(Now, only loud shouting can be heard). |
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| Even greater improvements in
soundproofing the wall can be gained by: |
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| * adding an additional layer of
drywall on channel to the other side. |
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| * adding a layer of "Wonderboard" or
"Duroc" a concrete based construction material to add more mass (this
will help reduce low frequency sound). Add to existing wall, first.
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| * adding a layer of "Super
Soundproofing Silencer "Mass Loaded" Barrier" to the existing wall
or adding a layer of Super Soundproofing absorbent Mat" to the existing
wall, or both. |
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| * mounting "Soundboard" (Celotex-sound
deadening board) or "Homasote" to the
channels before the drywall is attached. Caulk and seal the edges of the
panels for best results. |
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* using
natural
cotton fiber instead of fiberglass batting. |
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For maximum effect and best results: use "all of the above".
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| Channel Cutting:
Resilient Channel can easily be cut with tin-snips or
hacksaw. |
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| Installation:
Walls require less channel than a ceiling for obvious reasons. If they are
to be fitted directly to the underside of an existing ceiling, furring
strips should be screwed to the ceiling at 2' centers, right angle to the
joists. |
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| The absorbent mat of the appropriate
thickness should be applied inside the joists/studding before this stage.
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| Care must be taken to ensure that the
attachments used are secured to the underlying joists where they cross and
NOT just to the existing drywall. |
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| The channel should be screwed to all of the
strips with drywall screws. Channel should be joined by overlapping them by
a few inches with the corrugated webs nested together and BOTH base flanges
screwed through to the strip beneath. A "pop" rivet would add extra security
to the channel joint. |
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| Drywall Installation:
Furring strips are usually not required unless added dead air
space is needed in the new wall/ceiling. A panel of 5/8" "Firecode" Drywall,
or similar composite ("Sheetrock, Plasterboard", "Gypsum
board" etc), should
be used and fitted to within ¼" of the surrounding walls/ceiling. Joints
should be staggered in all directions. ALL joints should be secured to the
resilient strip with the appropriate length screws close to their edges.
Adding our tape
to the channel pads the metal where it touches the wallboard. (If the
panel is not covered with mat already). |
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| Attaching:
Secure the first of the material to be used to the resilient channel with
the appropriate length drywall screws, making sure that the screws ONLY
penetrate the corrugated web part of the resilient channel. IT IS
ESSENTIAL THAT THE SCREWS ONLY PENETRATE THE CORRUGATED WEBS AND DO NOT COME
INTO CONTACT WITH THE RESILIENT channel base SUPPORTS OR furring
strips. Do not overly tighten the screws or they may pull through the thin
metal channel. Just "snug" them. |
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| Attach the second layer of material (drywall)
using the correct length LONGER screws taking care to offset the joints of
the first layer and screw only into the first layer of material, not into
the resilient channel. (If not using a panel adhesive, a few screws may be
put through to the channel if need be). A ball peen hammer will dimple
the drywall for help in setting the screw heads. Do not break the
paper facing of the drywall panels with the screws as a reduction of
strength will result. |
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| Edge Sealant: Flexible acoustical
caulking
compound that will remain flexible for years should be applied to ALL
the edge perimeters after the installation of EACH layer to achieve optimum
results. |
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| Finishing: |
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| All drywall joints should be finished with
traditional jointing methods and plaster covered before painting/decorating
the deadening wall in the normal manner. Do not heavily "mud" the gaps. (Tape and Paint).
Protruding screws may be lightly tapped with a hammer and carefully
tightened some more by hand. |
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| Resilient Channel: Part/Number: "RC-1" |
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| Dimensions:
Steel Gauge : .018 |
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| Weight : approx.
0.37Kg/m |
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| Length :
Cut for UPS shipping: ( 6’) |
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| Availability: Manufactured by "Unimast". Check
with them or your local Builders Supply for availability in 12' length,
otherwise order from us. (We cut to 6' for UPS shipping:). We
also have RC-2 and DWFC. |
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| Performance: |
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| When installed beneath an existing ceiling
with soundproofing absorbent material applied as above, improvements in
reducing both airborne noise and impact sound would normally be well in
excess of 300%. This means a STC in excess of 50: (Loud shouting can’t be
heard). Fire resistance would be about 1 hour. |
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| TIPS for Walls: |
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| Don’t allow the drywall sheets to set
directly on the floor. Use
vibration pads made of ribbed neoprene and cork to place under drywall
sheets for support when used for walls. Caulk well. Stagger joints.
Use metal tape on underlying joints. Caulk well. Don’t screw baseboard onto
both the pads and the wall base sill. |
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Alternative installation of absorbent mat: apply to the
inside wall or ceiling panel to be fitted against the resilient channel.
This may be somewhat easier than applying it to the existing wall or
ceiling. Adding
natural
cotton fiber instead of fiberglass batting will drastically increase
both thermal and sound insulation. |
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When installing the channel over thicker mat (like 1"),
don't pull mounting screws down too tightly. This will deform the
channel. Don't break the covering paper of the drywall with the screw! |
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Remodeling a typical wall for average sound reduction: Apply
Mass Loaded Vinyl (MLV) directly to the existing wall. (Two layers is
best). Stapling will hold it temporarily in place. Now install at least one
layer of 5/8" firecode drywall over it. Tape off and paint your
sound deadening wall. This
will more than double the sound reduction of the existing wall.
Remodeling a typical wall for even more sound reduction:
(Where existing wall has little or no sound blocking qualities). Take
drywall off on one side, then the joists/studding, electrical boxes
inside is caulked well (make sure both sides do not have boxes in line or
sound will have a direct path through the wall!) and our 1/4" acoustical mat is glued to the opposite
inside wall and the exposed studding is covered, too. Our "Silencer"
flooring (MLV) is stapled to the joists/studding, covering the ceiling/wall
completely. Seams are sealed with caulk or tape. (Lead tape
improves the seam seal). For an 8' high wall, three RC-1 channels are
installed horizontally over the wall, one in the middle, one at the top and
bottom, located a few inches down to avoid the footer and header. Then
5/8" "firecode" drywall (this is now also available with a lead foil
covering) and is laid out on sawhorses and covered with a layer of the 1/4"
foam mat using contact cement and a roller. These panels are installed with
foam facing the channels with screws and is supported by 2" square vibration pads
located every 2 feet or so. The bottom of the drywall is caulked tight
and the seams too.
Additional soundproofing material will increase the sound control ability
of the wall in proportion to the type and amount added, such as adhering
additional panels together with "Green
Glue" which increases the mass of the wall. The visco-elastic glue
acts as a sound dampener as well.
Be sure to cover the entire wall, no gaps left open. Gaps amounting
to 2-3% of the wall covered can reduce the effectiveness of the job by 50%!
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Due to vast differences in the care taken using these
installation techniques, information contained in these instructions is
given in good faith but without any kind of warranty.
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The EPA Manual has more
information on this and other techniques.
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| See our
prices pages for product/cost information and availability or call for
free consulting! 760-752-3030 |
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NEW! Sound Control Clips with
DWFC hold the
panels better and are easier to install than resilient channel: Get more
than double the STC of resilient channel! Call about the new
SuperSound Clips
and DWFC.
We have
Green Glue too!
PRINTER
FRIENDLY VERSION
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