Blog RSS Feed

Understanding and Managing Sound Transmission Reduction in Walls

Managing Sound Transmission
Managing Sound Transmission

Posted on Wednesday, January 24, 2018
Categories: Soundproofing  |  Insulation

Controlling sound transmission through walls and floors in a home or office is often a highly-desirable outcome, however it can also be an often-illusive result without the proper education on audio characteristics. Advances in technology in recent years have made it an easier outcome to conquer. Before we can discuss the best options for controlling sound transmission from one room to the next, you must understand STC Ratings.

Soundproofing products often come with a Sound Transmission Class (STC) rating. STC is a measure of how many decibels of sound reduction a product provides. The higher the STC rating, the better. An improvement of 10 STC makes the noise seem like it’s been cut in half. On the other hand, a rating difference of 3 STC or less is nearly imperceptible to the human ear. This is worth knowing when comparing products.

Think of sound like water… if a vessel isn’t entirely sealed, it will leak. It is important to note that there are nearly infinite field conditions that will affect sound ‘leaking’ when designing or remodeling building partitions and enclosures. Partitions that are inadequately or inappropriately sealed—that contain back-to-back electrical boxes, untreated recessed lighting, and unsealed pipes to name just a few—provide flanking paths for sound. Sound flanking paths include any sound transmission path other than the wall or ceiling partition itself. Great care and caution must be applied to any acoustically-treated building partition

For instance, a one-inch square hole in a one hundred square foot STC (Sound Transmission Class) 50 wall will reduce the acoustical value of that wall to an STC 39! Many causes significantly influence acoustical performance and sound transmission other than the details of wall or floor construction. All of these conditions must be considered when developing the sound conditioning design.

An excellent STC targeted rating on an interior wall would be 60 or greater. This is considered superior soundproofing where most sounds are inaudible. An ideal rating for a media room or recording studio.

Typical Residential Interior Wall Comparisons

Typical Residential
Interior Wall Comparisons 

Here are three common interior residential wall assemblies for comparison in understanding what you may be hearing now.

A typical interior wall – which most people would refer to as ‘paper thin’ when judging it for sound transmission – has an STC rating of approximately 33. This includes single layer standard ½” drywall on each side, 2x4 wood studs on 16” centers, and no insulation between the studs.

An enhanced interior wall application would have an STC rating of approximately 45. This would be comprised of a double layer of standard ½” drywall on each side, 2x4 wood studs on 16” centers, and standard fiberglass batt insulation between the studs.

An excellent interior wall application will have an STC rating of approximately 63. This would include a double layer of standard ½”drywall on each side, double wood or metal studs on 16” centers with a 1” air space between them, and standard fiberglass batt insulation between both rows of studs. This wall assembly would be a total of 10” thick.  However, new advances in technology are delivering equal or greater STC results while reducing the bulk of the wall.

In recent years, a great deal of focus has been placed on sound transmission in residential homes. This focus is due, in part, to the rising popularity of home theaters.  A few of the most popular and most effective products and techniques are listed below:

Decoupling

Decoupling 

Structurally decoupling the gypsum wallboard panels from the partition framing can result in a large increase in sound isolation when installed correctly. Examples of structural decoupling in building construction include resilient channels, sound isolation clips and hat channels, and staggered or double-stud framing. The STC results of decoupling in wall and ceiling assemblies varies significantly depending on the framing type, air cavity volume, and decoupling material type. Great care must be taken in each type of decoupled partition construction, as any fastener that becomes mechanically (rigidly) coupled to the framing can short-circuit the decoupling and result in drastically lower sound isolation results.

Homasote® 440 SoundBarrier®

Homasote 

[homasote website]

Independently lab-tested and time-proven in millions of square feet of residential and commercial structures, 440 SoundBarrier® is a special-density, structural board made from 100 percent environmental Homasote® cellulose fiber, a homogeneous composition manufactured with uniformly distributed protection against termites, rot and fungi and resistance to moisture. It also insulates, with twice the R-value of wood. Made with FSC® certified material.

There are a multitude of possibilities and combinations of products and wall assemblies that deliver enhanced STC ratings. A 5-1/4” thick residential wall for comparison, would include a single layer of their Homasote® 440 ½” sound board on one side, 5/8” thick Type X Gypsum Wallboard on both sides, 2x4 wood studs on 16” centers, and standard fiberglass batt insulation between the studs. This wall assembly would produce an STC rating of 52.

QuietRock® Sound Reducing Drywall

QuietRock 

[quietrock website]

QuietRock®, the first and most technically-advanced sound reducing drywall, was developed in 2003. In addition to the award-winning QuietRock®, a complete line of Quiet® accessory products are available to complete the application. These products reduce sound and vibration in a multitude of applications by utilizing modern chemistries, techniques and a Silicon Valley approach to building science.

A typical 4-1/2” thick residential wall for comparison, would include a single layer of their QuietRock® 510 ½” drywall on both sides, 2x4 wood studs on 16” centers, and standard fiberglass batt insulation between the studs. This wall assembly would produce an STC rating of 52.

Rockwool® Stone Wool Insulation

Rockwool 

[rockwool website]

ROCKWOOL SAFE’n’SOUND® is a batt insulation designed specifically for interior wall and floor/ceiling applications. This stone wool insulation is made from natural stone and recycled content. It’s a green product that provides superior sound absorbency and fire protection for overall comfort and safety.

Because SAFE’n’SOUND® is designed for interior applications, it has not been engineered as a thermal insulation but as a fire barrier and for soundproofing. Stone wool in general has excellent fire ratings, does not burn and can add valuable time for evacuation in the event that a fire occurs. Its higher density properties also make it an ideal solution for minimizing sound traveling between rooms.

A typical 4-7/8” thick residential wall for comparison, would include a single layer of 5/8” thick Type X Gypsum Wallboard on both sides, 3-5/8” steel studs on 24” centers, and ROCKWOOL SAFE’n’SOUND® insulation between the studs. This wall assembly would produce an STC rating of 52 in addition to a 1-Hour fire resistance!

Tagged:home improvement, insulation, soundproofing, remodel

Add a Comment
« Previous Post Next Post »

Locations

Our locations are here to serve you

Gilbertsville, PA
(610) 367-2036
info »

Pottstown, PA
(610) 327-1120
info »

Bethlehem, PA
(610) 868-2010
info »

Kutztown, PA
(610) 683-7391
info »

 

Connect With Us

Instagram Facebook Google+ LinkedIn Blog

Contact Us

Have a question or need a quote?







* denotes required field

 

LBM True Value NARI-BIE Tri-County Area Chamber Philadelphia Reserve Supply Co.