What Type of Insulation Is Best for Soundproofing?

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What type of insulation is best for soundproofing?

To be honest, there is a few selections of soundproofing materials that offer both block sound and thermal insulation.

Such materials would be ideal for soundproofing a basement if you’ve to prevent heat loss and offer noise reduction.

Probably you’ve transformed your basement into a home theater, office, or man cave.

For example, a basement underground would be ideal for a home theater, but the ceiling would require acoustic sound treatment.

This will prevent the stomping noise from the annoying upstairs neighbors.

A-List of The Best Insulation for Soundproofing

Several types of insulations offer soundproofing benefits. There are mainly 5 different insulations, and they include:

  • Fiberglass Insulation
  • Mineral Wool
  • Blown-In Cellulose
  • Foam Board

1. Fiberglass Insulation

Fiberglass is mainly made from melted plastic spun into wool and further reinforced with microscopic glass fibers.

This porous material traps air hence keeping the room cool in the summer and warm in the winter.

Additionally, it absorbs sound just like normal sound-deadening materials.

I’ve previously recommended this product for soundproofing and insulating the basement ceiling.

Unfortunately, because it’s light, fiberglass insulation can’t block low-frequency sounds but instead absorbs them.

It absorbs medium and high-frequency sound waves like acoustical wallpapers or soundproofing paint, with only thermal insulation being the added benefit.

Normal 3-1/2″ thick fiberglass batts can improve wall STC ratings from 35 to 39.

Unfortunately, because this product falls short in soundproofing, it’s always recommended to combine it with other materials that are correctly soundproof.

For example, sandwiching fiberglass in a layer of two drywall boards will significantly help boost blocking both impact and airborne noises.

A perfect example of fiberglass insulation is the Owens Corning RU41 Fiberglass Insulation.

It’s available in rolls and batts that deliver performance, quality and value.

The product is made from formaldehyde-free materials and meets and exceeds standards for indoor air quality set by GREENGUARD.

It’s also made of 100% renewable energy with flexible blanket insulation.

3. Mineral Wool Insulation

Mineral wool is a superior insulation material in many ways compared to fiberglass insulation.

It boasts a higher R-Value per inch than fiberglass- precisely- 22-37% improved R-Value.

Additionally, mineral wool contains 70% recycled materials hence an environmentally friendly material compared to 20-30% recycled materials.

Additionally, it’s denser than fiberglass (3times denser), guarantying superior sound deadening properties.

The product is hydrophobic and won’t absorb water or facilitate mold growth and mildew.

And the best part is that the product is fire resistant and can serve as a fire stop.

Unfortunately, mineral wool insulation has its own drawbacks.

It’s 25%-50% more expensive than fiberglass and not available in a wide range of sizes.

Because of its density, it’s heavier, making it a challenge when insulating and soundproofing a ceiling.

Its mass/density nature requires using a wood saw or serrated bread knife to cut it down to size.

A recommended mineral wool insulation is the ROXUL Rockboard 60.

It’s sold in 2″ thick 2’x4′ board sizes and can easily fit into wall framing cavities.

Its rigidness allows it to be cut into different sizes and any insulation project.  Additionally, the product can be used to make acoustic bass traps.

Then there’s the ROXUL Rockboard 80 with a density of 80. It is excellent for use inside ceilings, walls, floors, and independent framed panels that can be hung anywhere to deal with echoes and reverbs.

ROXUL Acoustical Fire Batts are water, moisture, and mildew resistant and are perfect for insulation and soundproofing projects.

3. Polystyrene Foam Board

Expanded Polystyrene (EPS) is used to protect fragile items in their packaging.

It’s also the same material your disposable coffee cup is made out of.

The material gives an R-value of 4 per inch thickness, and it’s also one of the most affordable foam board insulation on the market.

Then, the extruded polystyrene is available in blue or pink foam boards and is much stronger and denser than the expanded polystyrene.

The boards can fit perfectly into drop ceilings (when cut into shape), and this helps reduce sound transfer and aid thermal insulation.

Additionally, Styrofoam products are also used in camp coolers as they offer the best thermal properties.

Extruded Styrofoam boards are closed-cell foam, while expanded foam boards feature an open cell construction. The two have an STC rating of 37 and 39, respectively.

When this product is used in normal wall partition construction, it can significantly improve the STC rating to between 51-55.

Polystyrene boards work perfectly for exterior wall applications and can be combined with fiberglass or mineral wool panels to improve sound deadening.

Note: Styrene found in polystyrene is considered carcinogenic. (Source)

4. Spray Foam Insulation

Besides moisture and building temperature control, spray foam insulation is also used to reduce noise.

The product is created when polyol resin and isocyanate are mixed.

It expands by up to 30-60 times when sprayed in place.

It is an excellent alternative to traditional insulations such as fiberglass.

Foam insulation acts as a barrier to airborne sounds, which significantly reduces airborne noise transfer through the walls, roof, and floor.

You’ll be glad to learn that in the United States, any home treated with spray foam insulation qualifies for federal and state tax deductions. (Source)

5. Blow-in Cellulose Insulation

Blown cellulose comprises 70-85% recycled paper with the remaining 30-15% are fire retardant materials.

The product has STC and NRC ratings of 44 and 0.80, respectively.

It can be added to the ceiling, walls, and floors during the construction phase to reduce vibration resonance.

It’s available in wet, loose, or dense-pack, providing both thermal insulation and noise reduction.

The dense pack is blown into ceiling, wall, or floor cavities under very high pressure, while the loose packs under low pressure.

One of my most recommended blow-in insulations is U.S. GREENFIBER LLC INS541LD.

So, What Type of Insulation Is Best for Soundproofing?

Now that you’re aware of the different types of insulation available on the market today let’s look at What type of insulation is best for soundproofing.

To be precise, it all depends on different factors, including application, installation, and your budget, of course.

The only product that I would recommend in this case is fiberglass insulation.

It’s both affordable and highly effective in thermal and sound insulation.

It is used in home soundproofing and in the automotive industries in the manufacturing of quiet performance mufflers.

A great alternative is mineral wool insulation.

It’s denser and has more mass than fiberglass insulation.

However, the only downside is that it’s twice expensive as fiberglass.

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