Messages and Online Forum Q&A

Re: Interior Wall Sound Control

From: info@builderswebsource.com
Category: Insulation / Sound Attenuation
Remote Name: 63.198.181.43
Date: 17 Feb 2001
Time: 08:30 PM

Comments

Unless your local building codes require a flame spread less than 25, you can use faced or unfaced batts. If you use unfaced batts, these fit between the studs using a "friction fit." Just make sure the width of the insulation is just slightly wider than the spacing between the studs. Standard 3-1/2" R-11 or R-13 insulation fits easily between 2x4 studs on 16" centers.

However, most insulation manufacturers also market a sound attenuation product, such as JM's ComfortTherm, Owens Corning's QuietZone or CertainTeed's NoiseReducer, for example. While some of these batts are unfaced, most are faced or fully sealed in a special poly-wrap exterior surface that seals in the fibers, reducing airborne insulation fibers during installation. The following chart from Johns Manville's website shows typical available sizes:

For best sound attenuation, use the thickest insulation you can find to fit the wall cavity and seal air leaks around the room. Forcing insulation into a wall cavity may actually reduce performance, so always select the right thickness for the wall.

If you use insulation in a ceiling, remember to observe proper clearance around recessed lights, which is typically a minimum of 3" in all directions.

Also, if you have a second floor above a first floor, one of the best techniques for reducing sound transmission is to combine ceiling insulation with resilient sound isolation channels (called RC-1) running perpendicular to the bottom of the ceiling joist of the first floor. This greatly reduces impact noise from above, keeping your home quiet. Using these on walls also works well. Sound channels add about 1/2" extra depth, so you must account for this when specifying door jambs for interior partitions.

Sealing all cracks and penetrations (including electrical boxes) with a high quality acoustical caulking -- such as Owens Corning QuietZone Acoustic Caulk -- also helps to keep sound transmission down. This specially formulated latex caulking is non-drying and non-hardening, which is important to retain its sound isolation properties for the lifetime of the product.

While more dramatic measures are possible to provide highly soundproof structures, including the use of double walls, double layers of drywall or the new QuietZone acoustic wall framing system by Owens Corning, these measures work best as part of a new construction project where superior STC ratings are designed into the structure from the outset.

For additional resources on insulation, see the Builders Websource Insulation Links section.

Builders Websource

Article Tools

Builders Websource® is a corporate member of ASTM International—a non-profit engineering body dedicated in part to the standardization of building materials specifications, products, systems, and test methods for improved health, safety, and reliability of residential and commercial structures.

Copyright © 1999 - 2018 Builders Websource®, a BUILDERA™ company. All rights reserved.