Author Topic: Two layers SafeNSound gain for ceiling  (Read 2761 times)

logistoit

  • Guest
Two layers SafeNSound gain for ceiling
« on: June 12, 2015, 06:46:30 PM »
What is the gain if any for installing 2 layers instead of 1 of Roxul SafeNSound between ceiling joists for an apartment conversion to condo ?

Randy S

  • Senior Soundproofing Technical Specialist
  • Global Moderator
  • *****
  • Posts: 793
    • Super Soundproofing Co
Re: Two layers SafeNSound gain for ceiling
« Reply #1 on: June 12, 2015, 07:26:28 PM »
Not much, since the purpose of the insulation is to absorb sound that is in the cavity.
if your addressing impact noise the best principle applied would be decoupling from the joist using clip and channel.
if your just addressing airborne sound then mass becomes the best principle applied by doubling the mass of the ceiling system or greater.
If you are dealing with both then you apply all principles, absorption in the cavity, clips and channel and double mass to reduce both types of noise issues.

Randy S.
760-752-3030 ext 3095
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

logistoit

  • Guest
Re: Two layers SafeNSound gain for ceiling
« Reply #2 on: June 13, 2015, 01:51:44 AM »
Not sure I understand. When speaking about cavity my understanding is that this is the space between the joist. Current ceiling joist are 24 inches apart and 9.5 inches deep. Wouldn't the noise from above floor be more absorbed with 2 layers x 3inch thick = 6 inches thick instead of 1 layer of 3 inches ?

Current ceiling to be renovated has old 194* metal tiles with some areas with old bat. Underneath is old suspended ceiling that was removed.
We are removing everything starting over from scratch.
Final ceiling will be suspended Fireguard tiles.
See provided pictures at this DropBox link:
https://www.dropbox.com/sh/rf7jdqcb6d1f30t/AACxOaf7CcLnxs6LyQKcyEOxa?dl=0

I get the idea of double mass and I would do that if ceiling could be completed with with gyps.
But it cannot as a lot of new stuff was added over the years under the joist (plumbing, cabling, electric wires,etc.). It requires suspended ceiling grid.

In this case what is the recommended insulation technique ?
I was thinking SafeNSound (1 or 2 layers?) between joist +  polythene membrane + wood slats to hold everything up there + fireguard suspended ceiling. Thought of adding Sonopan instead of polythene+wood slat (worth it ?).

What is clip and channel technique ? I assume resilient channel technique. Not sure about clip.

Thanks Randy

Not much, since the purpose of the insulation is to absorb sound that is in the cavity.
if your addressing impact noise the best principle applied would be decoupling from the joist using clip and channel.
if your just addressing airborne sound then mass becomes the best principle applied by doubling the mass of the ceiling system or greater.
If you are dealing with both then you apply all principles, absorption in the cavity, clips and channel and double mass to reduce both types of noise issues.

Randy S.
760-752-3030 ext 3095

Randy S

  • Senior Soundproofing Technical Specialist
  • Global Moderator
  • *****
  • Posts: 793
    • Super Soundproofing Co
Re: Two layers SafeNSound gain for ceiling
« Reply #3 on: June 16, 2015, 04:18:59 PM »
Thank you for the drop box link...you have a lot going on here and the end result is not going to be dramatic.

Since you are not doing a hard lid on a channel system you will not get the value of mass, therefore your original idea of double insulation is the best you can do. I would not add the wood slats to hold everything up just use insulation wires.

 I would go one step further and do the insulation as planned up in the cavity and I would also add another layer of insulation on top of the grid system as your installing the panels.

Randy S.
760-752-3030 ext 3095
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

logistoit

  • Guest
Re: Two layers SafeNSound gain for ceiling
« Reply #4 on: June 17, 2015, 06:20:08 AM »
Hi Randy,

Thanks for your response. Great input.

The original idea of the wood slats was to hold up both sheet of polyethylene + bats.
The sheet of polyethylene purpose is to cut down any possible odors or fumes that may travel upwards to the above appt.
I wonder if the polyethylene can also have any sound barrier benefits similar to the sound obstruction effect of a plastic bag over someone's mouth ;)

I am not familiar with insulation wires.
Do you have web references of that and how it's installed ?
Can I use that instead of wood slats if I install the polyethylene?

Thanks
JM
Thank you for the drop box link...you have a lot going on here and the end result is not going to be dramatic.

Since you are not doing a hard lid on a channel system you will not get the value of mass, therefore your original idea of double insulation is the best you can do. I would not add the wood slats to hold everything up just use insulation wires.

 I would go one step further and do the insulation as planned up in the cavity and I would also add another layer of insulation on top of the grid system as your installing the panels.

Randy S.
760-752-3030 ext 3095

Randy S

  • Senior Soundproofing Technical Specialist
  • Global Moderator
  • *****
  • Posts: 793
    • Super Soundproofing Co
Re: Two layers SafeNSound gain for ceiling
« Reply #5 on: June 17, 2015, 08:38:24 PM »
yes you can use these for the polyethylene.

Type " batt insulation supports" in google and you will see many.

Randy S.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

 

anything