Dampen Sound with Stone Wool
By Matt Weber
Keith and Toni Lively built their new home with an eye on the future. They wanted a large place for their kids and grandkids to congregate, plenty of rural property for off-road action, and ultimately to offer the new house and scenic playground as a destination place for newlyweds.
Of course, family reunions and wedding activities bring plenty of noise, and Keith and Toni wanted to keep the high volume out of their master bedroom. They turned to Roxul stone wool insulation for a solution.
Stone wool is a rock-based mineral fiber insulation comprised of basalt rock and recycled slag. Basalt is a volcanic rock, which is abundant in the earth, and slag is a by-product of the steel and copper industry. The minerals are melted and spun into fibers that are made into batts.
For sound control, Roxul offers Safe ‘n’ Sound stone wool batt insulation designed specifically for interior wall and floor/ceiling applications. Suitable for residential wood and steel stud construction, these non-combustible, lightweight batts have excellent acoustical dampening properties. Its high density makes it an ideal solution for reducing sound travel between rooms.
Sound comes from vibrations travelling through air, water or solids. When a baby cries. For instance, the vibrating vocal cords cause air particles to radiate out in all directions. These radiating air particles exert force on other air particles, causing more vibrations, which in turn, collide with more air particles. The density of stone wool material helps to absorb and block this airborne noise.
Additionally, stone wool in general has excellent fire ratings, does not burn and can add valuable time for evacuation in the event of a fire. The material will not promote corrosion, plus it’s resistant to water, rot, mold, mildew and bacterial growth.
The batts are also dimensionally stable, which makes them ideal for easy friction-fitting into walls, ceilings and floors.
The Roxul product is a breeze to install. The only thing that could be easier is if maybe the batts unpackaged themselves and then leapt into to their new homes between the wall studs. The batts come in precut sizes to fit between common 16-in. on-center stud spacing. To install simply push the 3-in. thick batts between the studs. That’s it. The pliable batts compress to fit and then the springy material pushes outward against the framing, which holds the batt in place. Zero fasteners are required. The spring-back nature of the material completely fills the wall cavity and prevents the insulation from sagging in the future.
Tip: Completely peel off all the plastic wrapping from the packages, because the batts can tear if you try pulling them out while they’re trapped in the wrapper.
The Roxul material is very easy to cut. A simple bread knife will do the job well. We also used an Insul-Knife from Cepco Tool, which has a long, wide blade for making deep, straight cuts in thick insulation material. The length of the Insul-Knife blade also enabled us to cut a few stacked batts at one time, which sped up our progress.
Since the Lively’s master bedroom was located in an upstairs corner of the house, Keith’s strategy was to insulate the wall separating it from the adjacent entertainment room, as well as insulate the floor joists that separate the room from a large downstairs banquet area.
If the wall’s stud spacing varies or an outlet box is in the way, you can easily notch the batts in place with a serrated blade. If the spacing is too large for a vertical batt, simply turn the batt sideways, cut it to fit horizontally, and stack the batts until the space is full.
By the time the job was complete, the ambient sounds we experienced working inside the room changed dramatically. Without a doubt, the Roxul Safe N’ Sound dramatically reduced noise transfer between the newly insulated walls. And with a couple of us working together, we knocked out this easy DIY job in just a couple of hours.
For more information on stone wool sound insulation, visit www.roxul.com.
The EHT staff recently toured the Roxul manufacturing factory in Marshall County, Mississippi. The new 600,000 sq. ft. facility was built in 2012 to produce a variety of the company’s insulation products. We learned how the stone wool insulation was made, and we were treated to an impressive demonstration of the material’s fire resistance.
The team at Roxul enlisted the local fire department to conduct what they called a “controlled burn.” Essentially, they built a large birdhouse from the company’s ComfortBoard Insulated Sheathing (a stone wool product that has enough structural integrity to assemble the structure). We then watched as a dish of chocolates was placed inside the birdhouse. Sitting atop a column of kindling that the firemen stoked into a raging inferno, the birdhouse was soon engulfed in flame. After blazing for several long minutes, the fire was extinguished and the Roxul staff retrieved the dish of chocolates from the smoldering birdhouse. The chocolates hadn’t even softened despite all the intense heat.
To watch a video of Roxul’s controlled burn, visit the Extreme How-To at blog.extremehowto.com.