Today we improve our home comfort with more strategic ways of eliminating room-to-room sound transmissions.
As mentioned last week, the most opportune time to do so is when renovating your kitchen, bathroom, or really any room in the home. Essentially, if you’re going to be moving or opening up a wall in order to redirect wiring, plumbing, or ductwork, then you might as well be taking advantage of this opportunity to create a little more privacy.
Why the need to block the transfer of sound? Because silence is golden, and after your 12-year-old has returned home with a set of bagpipes as his musical instrument of choice, silence will maintain your sanity.
What decreases sound from transmitting from point A to point B? Distance and obstacles. With the average residential building lot being anywhere from 50 to 60 feet wide, increasing the distance between the theatre room and your desktop computer is going to be a challenge.
So, we’re left with the alternative of obstacles.
Disclaimer: The following sound-blocking procedures will effectively muffle general sounds created in the home, however, the enactment of said procedures should not be used in falsehood, or as a crutch, for a person’s habit of selectively hearing.
Yes, we can reduce the sounds being transmitted by the loud operation of a television (producing about 60 decibels) being operated in room A, from entering room B, to little more than a whisper. However, a human cry for attention (producing about 80 decibels) should the lady of the home see a mouse, or be attempting to get a long-overdue chore completed, will indeed transmit through, albeit not quite in its entirety.
Regardless, if there’s no movement on the part of the person on the receiving end of this cry, know that it’s not so much the sound blanket doing its job, but the fact you are indeed being ignored.
With a regular, hollow-core wall assembly having a STC (Sound Transmission Class) rating of about 32, it would be nice to boost this wall assembly up to a STC 55, thereby muffling out most loud noises.
Step one: Fill the space in between the studs with Roxul’s Safe n’ Sound insulation, immediately boosting our wall assembly from a STC 32 to a STC 42.
Next, and before installing the drywall, fasten a sheet of 0.75”x4’x8’ Sonopan to your wood studs. Sonopan, recognized by its green colour and dimpled texture, is a lightweight fibre board that adds another 10 STC points to your wall assembly.
With both the Roxul Safe n’ Sound and Sonopan fiber sheets, our wall assembly now stands at an impressive STC 52.
Getting to our goal of STC 55 is going to require the help of a slight air space, along with a bit of solid mass. The air space will create a drum effect, further dissipating the transmission of noise, and will be provided by the addition of steel moldings, referred to as resilient channel. Installed horizontally at every 16 inches on centre, and placed directly over the Sonopan panels, the resilient channels will be fastened with 2.5-inch screws, reaching through the Sonopan, penetrating into the wood studs.
Avoid using regular 1×3 spruce strapping for the creation of an air space. The spruce’s mass will allow sound to reverberate through the wall, whereby the resilient channel’s mass is minimal, offering no route for the sound to follow.
Next, we follow up with two layers of 5/8” inch drywall, as opposed to a single layer of half-inch drywall. The 5/8” drywall provides the mass we’ll need to reach our goal of building an STC 55 wall structure. The first sheet of 5/8” drywall will be fastened to the resilient channel, but won’t penetrate the Sonopan board, while the second sheet of 5/8” drywall gets fastened to the first sheet, effectively creating a break in sound transmission.
Bonus to the 5/8” drywall is the double layer of fire-resistant product.
That’s how we keep things quiet.