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Best Soundproofing Insulation

Best Soundproofing Insulation: Comparison and Installation Tips

Soundproofing insulation is a key aspect in the process of soundproofing a room. It is a special type of insulation product, designed to be an acoustic barrier that absorbs sound and can greatly reduce noise transmission from one room to another.

Whether you are remodeling or building from scratch, having a good plan for soundproofing your walls, ceilings, floors, and even doors will set you up for a successful project. The result of installing the best soundproofing insulation will be a peaceful and private home or business environment for all to enjoy.

The rest of this guide will explain the many different types of insulation you can choose, where to buy it, where to use it, and how to install it. Once you understand the basics of this awesome and affordable soundproofing material, you’ll be ready to reap the benefits.

Benefits of Soundproofing Insulation

First, it is helpful to drive home the point that soundproof insulation is an acoustic barrier, not an acoustic treatment. That is, if you are wanting to make the sound in your room sound better, you should be looking into treatments like acoustic paneling, acoustic curtains, and acoustic foam. Soundproofing batts help block unwanted sound from entering or exiting in the first place by adding density to the construction of your walls and floors.

  • Reduce Outside Noise – Anybody who has lived or worked near a busy highway knows what a constant distraction the noise can be. Soundproofing the exterior walls of a building with mineral wool can help reduce the amount of road and city noise making its way inside.
  • Reduce Noise Leakage Indoors – Just like outside noise, soundproofing batts installed inside your interior walls can improve the sound environment indoors. The barrier prevents sound from exiting, as well as blocks unwanted sound from entering. You can imagine the benefits this can provide in homes, home theaters, studios, and office buildings.
  • Thermal Insulation – You might be surprised by this, but mineral wool, one the most common soundproofing insulations, also has good thermal insulating properties. You won’t have to sacrifice the ability to keep your building warm or cool when using this type of product.
  • Increases Home Value – Soundproofing your home with insulation is viewed as an upgrade in the real estate world. With it, your home’s value could be higher than others in your neighborhood, especially in densely populated areas, and those located near high traffic roads and highways.

Best Soundproofing Insulation: Acoustic Performance

There are three main types of materials used in acoustic insulation products: mineral wool, fiberglass, and cotton-based materials. Here is a brief explanation of the materials, followed by a table comparing the acoustic performance.

  • Mineral Wool Soundproofing – Also known as stone wool, or rock wool, this material has been around for many decades, but advances have been made in performance to make it ideal for soundproofing applications while not sacrificing the thermal insulating capabilities. Mineral wool is a natural material made from molten basalt and has an excellent natural resistance to fire and moisture.
  • Fiberglass Soundproofing – Fiberglass is an affordable alternative to mineral wool that has nearly the same acoustic properties, but is not quite as good thermally, and is not a natural material like mineral wool. Fiberglass is more challenging to work with and requires precautions to handle the fine glass fibers safely.
  • Cotton Soundproofing – Cotton based insulation is a cheaper material than fiberglass and is natural, but as a result, it is less versatile than fiberglass and mineral wool.  Acoustically, it’s still a good product, as good or better than either, just not the quite as high performance and no fire resistance.
ProductNRC125Hz500Hz1000Hz4000HzDensity
Mineral Wool – High Performance
Roxul Rockboard 60 (2in)0.950.321.061.021.046.0 lb/ft^3
Roxul Rockboard 80 (2in)1.000.430.900.971.008.0 lb/ft^3
Roxul Acoustic Fire Batts (AFB)0.950.281.091.091.072.5 lb/ft^3
Safe'N'Sound by Roxul1.050.521.181.071.052.5 lb/ft^3
Fiberglass – Multi Purpose
ATS Acoustics Rigid Fiberglass (2in)1.000.291.111.131.033.0 lb/ft^3
Owens Corning 703 (1in)0.700.110.680.900.963.0 lb/ft^3
Owens Corning 703 (2in)1.000.171.141.070.983.0 lb/ft^3
Owens Corning 705 (1in)0.650.020.630.850.956.0 lb/ft^3
Owens Corning 705 (2in)0.950.161.021.010.996.0 lb/ft^3
Cotton Batts
ATS Acoustical Batts1.050.271.171.151.062.5 lb/ft^3

1. Roxul Rockboard 40/60/80

Roxul Rockboard is rigid mineral wool panel product ideal for use as noise and thermal barriers. Rockboard is perfect for blocking noise in mechanical rooms, or any interior room where sound absorption and thermal insulation are both a priority.

While Rockboard has slightly lower sound absorbing performance, especially at lower frequencies, they have improved thermal insulating capabilities. With R-values over 4 per inch, these products could be used on the inside to soundproof exterior walls on top of standard thermal insulation.

Rockboard comes in three densities, 40 is 4 lb/ft3, 60 is 6 lb/ft3, and 80 is 8 lb/ft3. All boards are 24” wide and 48” tall and come in thicknesses from 1” up to 4”. The thicker the panel, the better the acoustic performance at the lower frequency levels. If your application has deeper, bass style noise, you’d better be using 4-inch thick Rockboard.


2. Roxul AFB (Acoustical Fire Batts)

Rockwool AFB is a similar Roxul product to Safe N Sound, sized specifically for steel stud walls or floors on the inside of commercial buildings. It’s also fire-resistant, water repellent, and won’t rot, sag, or attract mold.

It’s also much easier to find than Safe N Sound, so don’t let the “steel stud” sizing prevent you from considering it for your project. Steel stud batts are wider than wood stud batts, so you could simply slice a strip of material off the sides and stuff it into your cavity. It can also be used for other projects like voice booths, studios, and more.

AFB has an excellent sound absorption coefficient (SAC) of 0.95 and great performance at mid to high frequencies. The high density also aides in the reduction of low-frequency vibrations that can be so distracting.


3. Auralex Mineral Fiber Insulation

This Mineral Fiber insulation from Auralex is a high-performance mineral wool product and a great alternative to Safe N Sound. The best part is it’s easily available online from either Amazon or Auralex. The Auralex panels have a crazy high 8 lb/ft3 density, and the same qualities of thermal insulation, and fire and moisture resistance as Roxul.

The mineral fiber insulation comes in 24” x 48” panels, in both 2- and 4-inch thicknesses. 2-inch panels come 6 per box, and 4-inch come in 3 per box. For the best thermal properties, select the 4-inch version and get a combined R-value (insulating rating) of 4.2 per inch.

The 2” has an NRC of 1.0, and the 4” achieves an NRC of 1.05, putting it on par with Roxul Rockboard panels of the same thickness. The 2” thick batts provide soundproofing over a great range of frequencies, but the 4” will have the best low frequency performance.

  • High performing mineral wool insulation.
  • Two thicknesses (2” / 4”) available, providing options for any project.
  • Excellent soundproofing over a wide range of frequencies.
  • Material: Mineral Wool
  • Density: 8 lb/ft3
  • Thickness: 2 in / 4 in
  • Sizes: 24 in x 48 in

4. Roxul Safe N Sound

Safe N Sound insulation is a high performing mineral wool product that is perfect for soundproofing interior walls and ceilings. This product has superior fire resistance and excellent acoustic qualities, making it the best choice for soundproofing a variety of residential rooms.

Safe N Sound comes in two sizes, one for wood stud walls, and one for steel studs. Both are 3 inches thick, but steel stud batts are 1” longer and wider than a wood stud. Be sure to get the right one or the batts won’t stuff into the stud cavities as they should.

It has an NRC of 1.05, tops in the category, and best in class NRC at low frequencies and among the best at higher frequency ranges. The one issue with this product is finding a place to buy it. Many times, you’ll have to special order it if your local home improvement store doesn’t carry it.

  • Best insulation for interior soundproofing projects.
  • Excellent noise reduction across many frequencies.
  • Fire, Mold, and Mildew resistant.
  • Material: Mineral Wool
  • Density: 5 lb/ft3
  • Thickness: 3 in
  • Sizes: 16 x 48, 24 x 48 Wood or Steel Stud

5. Owens Corning 703 Fiberglass

Owens Corning is a familiar name in the industry, and the 703 fiberglass acoustic insulation has long been a go-to material for soundproofing projects. Mineral wool products have since taken away some of that popularity, but 703 fiberglass panels remain an effective soundproof insulation option.

Owens Corning 703 comes in 24” wide by 48” tall boards, in 1, 2, and 4 inch thick panels. Just like the best mineral wool insulation, you’ll want thicker fiberglass boards for better low frequency acoustic performance. For example, at 125 Hz the 1” boards have a SAC of 0.11 while the 4” boards come in at 0.84.

703 is widely available, but it’s pricey. 4 inch 703 can cost more than 2 layers of Rockboard or AFB, which may or may not be a big deal depending on the size of your project. ATS Acoustics Rigid Fiberglass is an excellent alternative product that looks and performs nearly identical to 703.

  • High performing fiberglass soundproofing insulation.
  • Well known and trusted brand name.
  • Easy to find a supply, although comparatively expensive.
  • Material: Rigid fiberglass
  • Density: 3 lb/ft3
  • Thickness: 1 in / 2 in / 4 in
  • Size: 24 in x 48 in

6. ATS Acoustical Cotton Batts

If you’re interested in more eco-friendly insulation that still has excellent acoustic properties, then look no further than ATS Acoustical Cotton Batts. ATS Manufactures the batts from a minimum of 85% post-industrial cotton fibers, and the batts themselves are 100% recyclable.

If you have a LEED requirement this may be your best and the only option, however, it is not recommended for any application that requires fire resistance. While it’s not fire rated, it does have a great microbe resistance.

The acoustic performance of ATS Cotton Batts is comparable to Owens Corning 703 and comes at a cheaper price. The flexible nature of cotton batts requires a rigid frame or backing, and it boasts SAC ratings over 1.0 for frequencies of 500 Hz and higher.

  • Sound absorption on par or better than fiberglass.
  • No nasty chemicals, VOC’s, or itchy fibers.
  • Eco-friendly, recyclable, and resistant to microbial growth.
  • Material: Cotton Fiber Batts
  • Density: 5 lb/ft3
  • Thickness: 2 in
  • Size: 24 in x 48 in

Installation Tips

Mineral wool and fiberglass soundproofing insulation can be purchased in packages of multiple panels or rolls of batts, depending on the type. They are manufactured with good tolerances and fits snugly in between wall studs and ceiling joists. They fit easily into the cavities with a friction press fit, ensuring there is no air gap for sound to leak into adjoining rooms. A simple bread knife with a serrated edge is enough to cut the batts to size.

The insulation panels are typically 2”-3” thick and are rigid enough to be easily cut to shape around electrical outlets and studs. You can use a drywall saw to precisely cut out the notches to make each panel fit into place. Wall and ceilings can be finished off with standard or soundproof grade drywall, no vapor barriers are required.

Soundproofing insulation panels can be purchased for wood or steel stud walls and ceilings. Make sure you pick the right version, or they won’t fit well in your wall cavity. Here are typical sizes of batts:

  • Wood Stud Panels: 15.25” x 47” x 2” or 3” Thick
  • Steel Stud Panels: 16.25” x 48” x 2” or 3” Thick

Of course, soundproof insulation is only a part of what possible. You can choose to go all out and build decoupled walls using hat channel, acoustic sealants, and two layers of drywall. Either way, you’re making a great investment in the comfort and utility of your home!


*Last updated 2019-08-25 at 11:43 / Product Links & Images from Amazon Product Advertising API

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