Rockwool vs Fiberglass Sound Insulation: Which Is Better?

The advancement of sound insulation has greatly improved.

From the days of using papier-mâché and straw to the use of dense, high-quality materials such as rockwool and fiberglass, there is now a wide variety of sound insulation materials to choose from.

For more than a century, humans have been searching for ways to create a soundproof environment.

Although we may not take it seriously, noise is a health hazard that can cause cardiovascular diseases and psychological problems such as depression and anxiety.

This post will take a closer look at two of the most popular soundproofing materials: rockwool vs. fiberglass insulation.

We will be comparing their properties, advantages, disadvantages, and applications to help you decide which one is better for your needs.

Rockwool vs. Fiberglass Sound Insulation: The Ultimate Showdown

Mineral wool vs fiberglass for soundproofing

When compared head-to-head, rockwool is better at the insulating sound because it’s denser than fiberglass.

It’s also more effective at blocking out sound frequencies within a certain range, making it ideal for use in music studios and other specialized applications.

However, fiberglass is more affordable and easy to install than rockwool.

It can be used for ceiling insulation or as an acoustic panel on walls and ceilings without any special training required by the installer.

What is Rockwool?

Rockwool is a man-made mineral fiber insulation made from volcanic rock.

It has been used for thermal and acoustic insulation for more than 100 years and is now one of the most popular types of insulation in the world.

Rockwool is available in two forms: slabs and batts. Slabs are large, flat pieces of insulation used in walls and ceilings, while batts are small, rolled-up pieces of insulation used in floors, walls, and ceilings.

Rockwool is a non-flammable material with an R-value of between 3.0 to 3.3 per inch.

It’s also very effective at absorbing sound, with a noise reduction coefficient (NRC) of 0.75 to 0.95 depending on the type and thickness of rockwool used.

What is Fiberglass?

Fiberglass is an artificial glass fiber used for thermal and acoustic insulation.

Unlike rockwool, it does not contain any minerals or metals but consists of recycled materials such as sand, soda ash, and limestone. It is available in two forms: batts and rolls.

Fiberglass insulation comes in a variety of thicknesses, ranging from 0.016 to 0.05 inches (0.41 to 12 mm).

The thicker the material used for soundproofing, the higher its R-value. That said, fiberglass generally features an R-value of between 2.2 and 2.7 per inch.

Comparative Factors

Best insulation for soundproofing: Rockwool or fiberglass

Rockwool and Fiberglass are more similar than they are different. The variables below could be used to compare and contrast the two materials.

  • Acoustic performance
  • Thermal characteristics
  • Fire safety issues
  • Sustainability elements
  • Durability and strength
  • Weight and fitting
  • Breathability

1. Acoustic performance

Rockwool and fiberglass are both excellent soundproofing materials.

However, in terms of its acoustic performance, rockwool has a slight edge over its rival. It offers greater noise reduction at higher frequencies than any other insulation material.

2. Thermal characteristics

Thermal conductivity measures the rate at which heat flows through a material. It’s measured in watts per meter kelvin (W/mK).

The lower the thermal conductivity, the more effective an insulation material will keep your home warm during winter and cool during summer.

Rockwool has a low thermal conductivity of 0.027 W/mK, making it an excellent choice for controlling heat flow in your home.

Fiberglass insulation has a higher thermal conductivity that ranges from 0.028 to 0.038 W/mK, but the variation is not significant enough to affect its performance as an insulating material.

3. Fire safety issues

Both rockwool and fiberglass are non-flammable materials with low ignition temperatures.

However, both materials can create toxic fumes when exposed to high heat or flames, making them a potential health hazard in a fire.

Rockwool is generally considered more fireproof than fiberglass as it burns slower and produces less smoke.

4. Sustainability elements

Rockwool is a sustainable product that doesn’t contain any harmful chemicals or gases and can be recycled for other uses such as horticulture.

It also contains between 50 to 60 percent recycled materials, making it an eco-friendly insulation material.

Fiberglass has a lower sustainability rating than rockwool as it contains up to 80 percent recycled materials.

However, fiberglass is also manufactured from non-toxic material and recycled at the end of its life cycle.

5. Durability and strength

Rockwool is a more durable insulation material that is less likely to sag or crumble over time. It’s also resistant to mold and mildew, making it a great choice for damp environments.

Fiberglass is less durable than rockwool as it can sag or crumble over time if incorrectly installed. In addition, the material is prone to damage from moisture over long periods of exposure.

As such, fiberglass insulation should not be used in areas frequently exposed to water.

6. Weight and fitting

Rockwool is a heavy material that weighs approximately three times more than fiberglass.

The weight of rockwool ranges from 20 to 45 lb/sq ft. It’s also available in large panels, making it difficult for homeowners with limited DIY skills to fit it themselves.

Fiberglass is a lightweight material that weighs between two and four pounds per square foot. It’s also available in small rolls, making it easy for homeowners to install without assistance.

7. Breathability

Both rockwool and fiberglass are breathable insulation materials that allow moisture to escape from your home.

However, rockwool is a more breathable material that can absorb up to 80 percent of its weight in water vapor before drying out.


How long can Rockwool last?

Rockwool insulation is rated for a lifetime of between 50 and 100 years, making it one of the most durable types of insulation available.

How do you install Rockwool?

You can install rockwool in your home by cutting it to size with a utility knife or saw and fitting it into place.

Use a vapor barrier to prevent moisture from entering the insulation.

How long can fiberglass last?

Fiberglass insulation has a lifetime of between 20 and 30 years, making it less durable than rockwool. However, you can recycle the material once its life cycle ends.

Why do you need a vapor barrier with fiberglass?

Fiberglass insulation is not as breathable as rockwool and can trap moisture inside your home.

A vapor barrier helps prevent condensation build-up and protects the insulation from water damage.

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