[hmen]

I'm replacing the ceiling in my basement and I'd like to put some kind of insulation between the studs to act as soundproofing. What would be the best reasonably priced material I could buy?

[WGH]

How about on top of the studs?

I get all sorts of emails since I am in the construction trade, most are trashed, but this looks interesting.

Lightweight - High Strength - Insulated -Sound-Deadening
Sing Honeycomb material
http://www.superhoneycomb.com/

I am not affiliated with this product in any way and have never used it, but it could have potential.

Wayne

[hmen]

Over the studs is the living room floor and part of the kitchen. I have about 12 inches to fill so I thought some kind of fiberglass insulation since it will be sealed. 

[MaxCast]

Adding R-13 will help.
How are your wall studs connected to the joists?
What type of material will you be using for the ceiling?

[bpape]

Fill the cavity with standard insulation.  Don't have to jam it in there but fill it full.  Double drywall below the joists - Green Glue between layers if you have the budget. 

The insulation is simply there to damp the cavity resonance.  The mass of the drywall is to:

- minimize sound transmission
- lower the resonant frequency of the cavity/membrane (drywall) to a point where there are fewer and fewer notes that will excite it and also makes it less efficient

Green Glue acts as a viscoelastic damping layer which never gets totally hard so that the 2 layers act both independently and as one at the same time thereby cancelling out some of each others vibrations.  Think of a spring tied to another spring with a weight on the end. Sometimes they move together, sometimes they move opposite.

Bryan

[TRADERXFAN]

Hi Bryan, or anyone?

What about that constrained layer damping drywall? I think one brand is "quietrock". Is that worth it?

[bpape]

It's a good product.  However, you have to REALLY look at their specs.  What they claim is for their best material which is over 1" thick and costs in the neighborhood of $80-$100 per sheet.  You can do 2 layers of 5/8 drywall and Green Glue and have better performance for less money. 

Some will say that it's double the labor and technically it is - however - if you'd ever tried to lift the big QuietRock, that's a whole different story.  You don't just throw that around by yourself.

Bryan

[JLM]

The ceiling/floor joists (not studs) must be physically isolated from the listening room ceiling in order to achieve much reduction in sound transmission.  In other words, filling the joist space with fiberglass (which is about as good as any material for this application) won't help a great deal.  And avoid recessed can light fixtures in that ceiling. 

There are a number of ways to obtain physical isolation.  If you already have a drywall ceiling, just use the Green Glue with another layer of drywall.  This might be the most desirable as it will result in the least loss of ceiling height.  If you don't already have a ceiling, I'd consider installing a drop ceiling grid with acoustical tile with mineral wool substrate.  Other options if you don't have a drywall ceiling already in place is to add Z or fully resilent channels between the joists and a layer of drywall.

[bpape]

DD and GG with a filled cavity will absolutely give you some help.  Is it as good as isolated drywall?  No.  However, a drop ceiling with mineral wool will lose you about 90% of the bass isolation that drywall will give you.  It simply doesn't have the mass to stop bass frequencies.

Now, if you have ceiling height and want to do it right, use RSIC-1 clips and hat channel and then hang your drywall from that.  Resiliant channel is great from an STC standpoint - but that ignores frequencies below a couple hundred Hz.  The RSIC-1 and hat channel is a far superior solution in the bass which is the hardest thing to stop.

Bryan

[TRADERXFAN]

Thanks for that info!

Does isolating the room do anything to improve sound quality IN the room?  I believe Geddes wrote that using the CLD drywall on rc1 damps bass better than (unspecified) absorption type bass traps in the room...


-Tony

[bpape]

Isolation of drywall on channel can provide some 'give' to the walls for sure.  In addition, any time you achieve isolation of sound coming INTO the room, you're lowering your noise floor which gives you more dynamic range potential and alleviates masking of low level details.

Bryan