CEILING SOUNDPROOFING

[Nufc23]

Ok experts here’s my situation

The condo I own has a lot of noise transfer to the condo above.
My plan is to:

Rip down existing drywall
Install Roxul Safe n Sound
Install side mounted isolation clips like these
    (https://csrbuilding.ca/product/resilient-sound-isolation-clip-1-%C2%BD-cold-rolled-channel-rsic-1-5crc/)
Install regular hat channel
Install one layer of quiet rock


My question(s) is/are:
1) Is this the best way to achieve maximum quieting of my neighbor?
2) is regular channel (hat) ok being I’m using the whisper clips?
3) can I use regular drywall wall or should it be quiet Rock?
4) If I use regular drywall is double layer with green glue between them the same as one layer of quiet rock?

Any other insight would be appreciated


Ed

[Randy S]

Ed,

If your using clips and channel why do you need the cold roll?
We use these clips and 20 gauge 7/8" hat channel
http://www.soundproofing.org/sales/ssp.htm

Double layer of regular 5/8" drywall with green glue is going to work better then quiet rock 510 or ez snap.

Randy S.

[duleaux]

I have a similar situation but a different strategy.  I live in an apartment in which I am trying to reduce airborne and impact noise from above.  I think I've read every article on the internet about how best to accomplish this goal, and virtually all of the "best solutions" involve tearing down the existing drywall ceiling which for me is not an option.  So here is what I am considering:

1.  Fill the cavities between the existing ceiling rafters by blowing cellulose insulation above the existing drywall ceiling
2.  Apply isolation clips (Whisper, isoTRAX, etc.) to the existing drywall ceiling (please read on, I realize this is considered bad practice)
3.  Apply hat channel to the isolation clips
4.  Apply 1" thick rock wool bats between the hat channel rails.  These bats will fill the space between the existing drywall ceiling and the new layer of drywall
5.  Apply new layer of 5/8" drywall (or QuietRock) to the hat channel rails

I realize that affixing isolation clips to an existing drywall ceiling is considered bad practice because it can create a mass-air-mass resonance chamber between the two layers of drywall that actually can worsen the noise.  However, in step 4, I would sandwich a 1" layer of rock wool (or fiberglass) bats between the two layers of drywall to fill the void and absorb the sound waves traveling between the existing ceiling and new layer of drywall.  So the final structure would have 10" of cellulose insulation between the rafters, the existing drywall ceiling, 1" of rock wool, and a new layer of 5/8" drywall (or QuietRock) affixed to isolation clips.  In the end, I won't achieve full STC reduction, but I assume this would provide some additional isolation of both higher-frequency and lower frequency airborne and impact noise.  Please let me know if you think this strategy has any merit.

[Randy S]

You are right on track when you can not remove the existing drywall.

I would use Isomax clips over any clip.
http://www.supersoundproofingsales.com/SSP-Clips-1/productinfo/09-IS/

Then I would apply 2 layers on the channel, first layer would be cement board 1/2" or greater followed by green glue then 5/8" type X drywall.
Quiet rock is not as heavy and cost way more.

Now the real issue with footfall is the existing subfloor, it is already a drum head and this is why we glue and screw cement board in between the joist in the cavity. when you can not do this you need to cut the perimeter of the existing drywall and fill the gap with acoustic caulking to break it from the walls. when you go forward all rigid layers are to have the perimeter gap and fill with caulking.

Feel free to reach out direct.

Randy S.
760-752-3030

[duleaux]

Thanks Randy!  Great feedback.  Unfortunately, the more I learn about this the more complicated and probably costly it becomes (for example, I did not think about caulking the drywall perimeters.)

[Randy S]

When ever you float on clips and channel or resilient channel you must leave the perimeter free from hard connections and only use non hardening caulk so you do not create a drum effect.
"tight around the perimeter and lose in the middle"

The true cost behind soundproofing is not so much the material as it is the labor costs due to the extreme amount of detail that has to be done in each and every layer.

Randy S.

[guarddog]

you must leave the perimeter free from hard connections and only use non hardening caulk so you do not create a drum effect.

I see this always mentioned, it is also visually covered on this page or your site.

I would assume this means you can't finish the drywall connection point between the ceiling and the wall in the normal way, as it would create a hard connection (and crack the drywall mud I would assume).

So my question is how are you supposed to finish the ceiling drywall edge?  If you leave a small gap of 1/8th or something which you then fill with acoustical caulk you would still have a funny looking ceiling edge.

Is there some type of trim you can butt the ceiling drywall up against to make a straight finished edge?

[Randy S]

The key to this is to make sure you are only using factory edge of the drywall and exact shim sizes.
once the caulking is installed use a caulking corner tool to finish while wet.
coat with a primer and paint, it actually looks good when done right.
if you are going to use molding simply caulk drywall gap first then when installing the molding leave an 1/8" from the molding to the ceiling and attach molding to the wall only and finish the same way with caulking the gap to the ceiling, primer and paint.

I've attached a photo of a corner done with just caulking and primer (before paint) ignore the foam bumper shown, this is for the isolated floor.

Randy S.
760-752-3030

[guarddog]

Yes, that looks good.  Using the factory edge always may not be so ideal, depending on the room.

I was thinking about using a corner bead as well as an option.  Just embedding the side on the ceiling and pushing the other edge up in the gap, then caulk.

I made a little image, attached.

So I could try the factory edge and use the bead if the factory edge does not work out well enough.

[Randy S]

Using the factory edge is my go to because on all my site visits I rarely find guys snapping drywall perfect and it is really visible from sheet to sheet around the perimeter.

I like your idea, how would you hide the corner bead and keep a straight caulking gap the length of the perimeter?

I am really interested in how that looks when finished. This is something we deal with often and is hard to fix without removing sheets of drywall. this could be an instant fix.