Mineral Wool- Which Density To Use?

[Andrew Raines]

I have contacted a local supply house for mineral wool and were given the following options:
1. 3" - 8# density

2. 2" - 8# density

3. 2" - 4# density

It seems logical that the mass of the 3"- density would work best, but they man at the supply house said that the "air" in the 4# density would most likely work best as a soundproofer.
Which would you choose?

Thanks in advance for your site & advice!!!
It's a wonderful thing!!!!

Do you know of a internet resource to obtain the "STC" Sound Transmission Classification of mineral wool, homasote and other "standard" building materials?

[Boborther]

Andrew,

I have been told (by a very reliable source) that the gentleman at the building supply center was absolutely correct. You want the  more airey wool which helps with your soundproofing effort, as opposed to packing in the mineral wool or using the more dense material.  I am not an expert on mineral wool, but I do know from experience, that it does indeed work. I also know that cut wool fibers from Johns Manville works even better than mineral wool, so keep that in mind if you have not already purchased the mineral wool.
Homasote, depending on the thickness, is approximately a 13 to 15 STC, 5/8" F/C drywall is an 8 STC,  1/2" drywall is generally a 6 STC, The MLV is a 26 STC, and soundproof windows are usually from 39 to 47 STC, and lead 1/64" thick is a 21 STC and 1/32" thick lead is a 32 STC.
Andy, that's my story, and I'm stickin to it. Laughs! Thanks for the post.

Bob Orther
Super Soundproofing Sales/Technical Associate.
Ph: (760) 752-3030    FAX: (760) 752-3040
URL: www.soundproofing.org
e-mail: boborther@soundproofing.org
For orders only (888) 942-7723

[John Hiser]

ahh, I too need some help in this area. I am not sure what "cut wool fibers" refers to. When I checked out the J.M. web site, they mention a line of acoustic products called "sound comfort." Are these the products you recommend over mineral wool. thanks, and sorry to butt in...

[Boborther]

John,

Mineral wool is a good product, as is Rock wool and cut wool fibers. There is also a great product made in Canada called Roxul (spelling?) it is also a good soundproofing bat type material.
Basically what we tell our customers is to stay away from the common pink or yellow fiberglass insulations. Hope this answers your question.
Cut wool fibers is a bat material that is used for thermal and sound isolation/dampening.


Bob Orther
Super Soundproofing Sales/Technical Associate.
Ph: (760) 752-3030    FAX: (760) 752-3040
URL: www.soundproofing.org
e-mail: boborther@soundproofing.org
For orders only (888) 942-7723

[John Hiser]

"Bat" usually refers to the stuff thats rigid, lightweight, easy to cut, but comes in long planks as opposed to the rolls?

[Boborther]

John,

It can also refer to materials that are enclosed in plastic bag like containers, that are placed in wall cavities and joist cavities to soundproof.
We are get down on the fiberglass insulation (the pink and Yellow stuff) because it has been proven to transmit noise quite readily through it's fibers. The Mineral wool, cut wool fibers, and rock wool do not transmit sound, and have great thermal qualities as well.

Bob Orther
Super Soundproofing Sales/Technical Associate.
Ph: (760) 752-3030    FAX: (760) 752-3040
URL: www.soundproofing.org
e-mail: boborther@soundproofing.org
For orders only (888) 942-7723