I'm removing my inner drywall and framing a new wall a foot away from my existing wall (keeping it a two leaf setup with insulation in between). This is to help isolate sound to my son's bedroom.
When I frame the wall, should I place anything under the 2x4's, or just bolt it to my concrete foundation?
Would it help to space rubber pucks underneath, or even along the entire length of floor?
The wall will be 14' in length.
Framing New Wall. . .
-
OftheSeven
- Posts: 13
- Joined: Wed May 04, 2005 8:11 am
- Location: Southern California (OC)
- Contact:
-
knightfly
- Senior Member
- Posts: 6976
- Joined: Sun Mar 16, 2003 11:11 am
- Location: West Coast, USA
By "foundation", I'm assuming you mean a concrete slab floor? If so, this is going to limit the usefulness of wall construction somewhat - the continuous concrete slab will transmit sound through between rooms fairly well. Some things you can do to make it better are heavy carpet and pad on the floors, and if the noise is REALLY drastic possibly even a resiliently supported flooring -
The wall frame itself should be as decoupled from the rest of structure as you can legally make it - Any bolts thru the frame into concrete will couple flanking noise from concrete into the wall, but will likely be necessary for seismic requirements; one way to improve isolation in this case would be to mount two layers of 5/8 drywall on Resilient Channel on the new wall frame - you mount the drywall using 1/4" spacers along the floor, resting the drywall on them until all screws are in place, then pull the spacers and use a high quality Butyl or Acoustic rated caulk to seal each layer as it's completed -
mud and tape all joints for each layer, or you will create a small void in the wall mass where the long edges are tapered; this will weaken isolation in two ways; one is to lessen the mass of the layer, and the other is to create a small "three-leaf" resonant cavity, at which resonant frequency the wall will be several dB weaker than it would if no voids in mass are allowed.
Even if you must bolt through the sill plates for seismic requirements, a layer of "sill seal" or other resilient material will ensure that the bottom plate is not allowed to rattle or vibrate against the concrete; this is more a precaution than any proven technique but I've not had problems doing it; it's just one of those things that "seems right".
If possible, don't hard couple the top plate to existing structure; there are resilient sway braces available to mount the upper end of walls, from companies such as kineticsnoise.com and masonindustries.com -
The joints around the perimeter of the new wall should be done so that no wallboard touches the existing walls - the same 1/4" gap (3/16" is enough, but not MORE than 1/4" should be left all around the perimeter, and each layer caulked after removing the spacers.
For corner bead, one of the newer flexible plastic beads with very thin mud at the actual corner, will help minimise coupling between old walls and the new one.
If it's within the budget, adding a second layer of wallboard on each side (2 wallboard, studs, space, studs, 2 wallboard) will help by about 6 dB across the frequency range - if you don't want to mess up the existing finished wall, you can add "inserts" between studs before insulating -
Hopefully helpful -
http://www.johnlsayers.com/phpBB2/viewtopic.php?p=22374
http://www.johnlsayers.com/phpBB2/viewt ... sert#19678
Also, if you decide to use Resilient Channel to mount the new wallboard on the new frame, be absolutely SURE you're actually getting RESILIENT channel; we've had a few cases of contractors putting standard "hat" type FURRING channel in which does NOTHING for isolation; in a couple of cases there will likely be law suits because of this. If you have any doubts as to what you're getting, please ask BEFORE you buy, or at least before you actually INSTALL the product. A posted digital pic is usually all it takes to identify what you have... Steve
The wall frame itself should be as decoupled from the rest of structure as you can legally make it - Any bolts thru the frame into concrete will couple flanking noise from concrete into the wall, but will likely be necessary for seismic requirements; one way to improve isolation in this case would be to mount two layers of 5/8 drywall on Resilient Channel on the new wall frame - you mount the drywall using 1/4" spacers along the floor, resting the drywall on them until all screws are in place, then pull the spacers and use a high quality Butyl or Acoustic rated caulk to seal each layer as it's completed -
mud and tape all joints for each layer, or you will create a small void in the wall mass where the long edges are tapered; this will weaken isolation in two ways; one is to lessen the mass of the layer, and the other is to create a small "three-leaf" resonant cavity, at which resonant frequency the wall will be several dB weaker than it would if no voids in mass are allowed.
Even if you must bolt through the sill plates for seismic requirements, a layer of "sill seal" or other resilient material will ensure that the bottom plate is not allowed to rattle or vibrate against the concrete; this is more a precaution than any proven technique but I've not had problems doing it; it's just one of those things that "seems right".
If possible, don't hard couple the top plate to existing structure; there are resilient sway braces available to mount the upper end of walls, from companies such as kineticsnoise.com and masonindustries.com -
The joints around the perimeter of the new wall should be done so that no wallboard touches the existing walls - the same 1/4" gap (3/16" is enough, but not MORE than 1/4" should be left all around the perimeter, and each layer caulked after removing the spacers.
For corner bead, one of the newer flexible plastic beads with very thin mud at the actual corner, will help minimise coupling between old walls and the new one.
If it's within the budget, adding a second layer of wallboard on each side (2 wallboard, studs, space, studs, 2 wallboard) will help by about 6 dB across the frequency range - if you don't want to mess up the existing finished wall, you can add "inserts" between studs before insulating -
Hopefully helpful -
http://www.johnlsayers.com/phpBB2/viewtopic.php?p=22374
http://www.johnlsayers.com/phpBB2/viewt ... sert#19678
Also, if you decide to use Resilient Channel to mount the new wallboard on the new frame, be absolutely SURE you're actually getting RESILIENT channel; we've had a few cases of contractors putting standard "hat" type FURRING channel in which does NOTHING for isolation; in a couple of cases there will likely be law suits because of this. If you have any doubts as to what you're getting, please ask BEFORE you buy, or at least before you actually INSTALL the product. A posted digital pic is usually all it takes to identify what you have... Steve
-
OftheSeven
- Posts: 13
- Joined: Wed May 04, 2005 8:11 am
- Location: Southern California (OC)
- Contact:
Thanks Steve - that was exactly the info I was looking for.
One question - how much more db reduction could I gain from using the resilient channel in this setup? Would it mostly be in the mids and highs, or lows as well?
I mainly track vocals and acoustic guitars. I program drums via sequencer, so I can control the volume.
One question - how much more db reduction could I gain from using the resilient channel in this setup? Would it mostly be in the mids and highs, or lows as well?
I mainly track vocals and acoustic guitars. I program drums via sequencer, so I can control the volume.
-
knightfly
- Senior Member
- Posts: 6976
- Joined: Sun Mar 16, 2003 11:11 am
- Location: West Coast, USA
RC ONLY helps in mids and highs; the low end is totally controlled by the amount of mass in each side of the wall, the distance between the two leaves of the wall, plus a bit what type/amount of insulation (don't EVER use any insulation you can't BLOW through, such as EPS, or other closed cell foams)
So for example, RC would probably help isolate the crack of a snare drum, but only slightly muffle the brightness of a kick drum and do NOTHING to stop the low "thump" -
For vox and acoustic guitars, (and voices coming INTO the space) the RC will improve things ONLY if both sides of the frame have wallboard hung on them ( a single frame, with wallboard mounted on both sides of that frame) - for a separate framed wall, RC is a total waste of money EXCEPT for the probable FLANKING you will get from your continuous concrete floor.
In YOUR PARTICULAR SITUATION, the RC isn't very expensive to add and may cut flanking transmission a few dB.
If you're at all concerned about ruined takes of vox and acoustic guitar, I'd put inserts between the studs of the old wall and two layers of wallboard on the new one... Steve
So for example, RC would probably help isolate the crack of a snare drum, but only slightly muffle the brightness of a kick drum and do NOTHING to stop the low "thump" -
For vox and acoustic guitars, (and voices coming INTO the space) the RC will improve things ONLY if both sides of the frame have wallboard hung on them ( a single frame, with wallboard mounted on both sides of that frame) - for a separate framed wall, RC is a total waste of money EXCEPT for the probable FLANKING you will get from your continuous concrete floor.
In YOUR PARTICULAR SITUATION, the RC isn't very expensive to add and may cut flanking transmission a few dB.
If you're at all concerned about ruined takes of vox and acoustic guitar, I'd put inserts between the studs of the old wall and two layers of wallboard on the new one... Steve
-
OftheSeven
- Posts: 13
- Joined: Wed May 04, 2005 8:11 am
- Location: Southern California (OC)
- Contact:
Is there anything at Home Depot or Lowes that would work?Also, if you decide to use Resilient Channel to mount the new wallboard on the new frame, be absolutely SURE you're actually getting RESILIENT channel; we've had a few cases of contractors putting standard "hat" type FURRING channel in which does NOTHING for isolation; in a couple of cases there will likely be law suits because of this. If you have any doubts as to what you're getting, please ask BEFORE you buy, or at least before you actually INSTALL the product. A posted digital pic is usually all it takes to identify what you have...
I already purchased these: http://soundproofing.org/sales/SSP.htm
-
knightfly
- Senior Member
- Posts: 6976
- Joined: Sun Mar 16, 2003 11:11 am
- Location: West Coast, USA
Those mounts will work fine; they use standard hat channel, which may indeed be available locally, if not a lowes or HD, then at normal lumber yards.
I wouldn't buy anything more from that site though, nor would I take their advice on much of anything; they are kind of a joke among more knowledgable people, and overpriced on most of what they sell; they sometimes recommend things you don't need, and just generally need to learn more about what they sell... Steve
I wouldn't buy anything more from that site though, nor would I take their advice on much of anything; they are kind of a joke among more knowledgable people, and overpriced on most of what they sell; they sometimes recommend things you don't need, and just generally need to learn more about what they sell... Steve