Rockwool Vs Fiberglass For Sound Deadening

Which is better for sound deadening: Rockwool or Fiberglass? This is a question that many people have, and the answer is not always clear. In this blog post, we will compare Rockwool and Fiberglass sound insulation to help you decide which one is right for you.

Acoustic Insulation & Sound Absorption

Acoustic is a term used to describe the ability of a material to absorb sound. When it comes to insulation, we want materials that will prevent sound from traveling through walls and ceilings. There are two ways to achieve this: by stopping the sound from entering in the first place (soundproofing), or by absorbing the sound once it is inside (acoustic insulation).

There are many different types of insulation, but the two most common types for sound deadening are Stone Wool (Popular brand name is ROCKWOOL), and the Fiberglass (Glass Wool). Let’s take a look at each one:

Rockwool Vs Fiberglass For Sound Deadening: Which Is Better?

Stone And Glass Wool

Stone wool and glass wool insulation are two of the most commonly used insulation types in residential construction. In this article we’re going to look at how they are made, the main differences, as well as their pros and cons.

Owens corning and Rockwool are the two most popular brands out there.

This product is usually called mineral wool insulation, but in fact they are both mineral wool insulation.

They’re just made up of different minerals. One is made of stone and rocks and the other is made of glass. Let’s start with stone wool.

Stone Wool (Rockwool)

It’s main ingredients are basalt rock slag, Coke and recycled Stone Wool waste. Basalt rock is a dark, igneous rock formed from the rapid cooling of molten lava. Slag is a byproduct of the smelting of metals like iron, copper, lead and nickel. When these metal oars are heated to high temperatures, the impurities, or slag, are separated from the molten metal.

Since it has been melted before it has a hive melt efficiency. Coke is a Gray, hard porous fuel with a high carbon content and few impurities. It is made by heating coal or oil.

In the absence of air, the recycled waste is crushed down into a fine powder and turned into briquettes. Basalt rock slag and the briquettes are ground down, washed and melted with Coke at 1500 degrees Celsius or 2700 degrees Fahrenheit to form molten lava.

The liquid is spun into fibre like strands 15 to 20 micro- meter thick. A binding solution made of phenol urea formaldehydrazin is added to the fibers to help them stick together. Oil is sprayed to enhance water repellency.

The Tufts of stone wool are carried on a conveyor belt to a pendulum device. The pendulum moves back and forth, spraying the stone wool in layers on another conveyor belt rollers compress the layers.

To make them denser. They are taken to a long oven and heated to cure the resin binders blades and water jet cut the stone wall into bats. A branding tool Burns the R value and the company name on the bats.

The most popular Stonewool manufacturer is Roxul, or Rockwool.

Bat is a semirigid product used inside homes on walls connected to the exterior. Comfort board is a compressed rigid product used outside homes for continuous insulation. Safe and sound is used in interior partitions.

Glass Wool (Fiberglass)

Now, let’s look at how fiberglass or glass wool insulation is made. Its main ingredients are sand or Silicon dioxide, soda ash or sodium carbonate, limestone or calcium carbonate and crushed up.

Recycled glass called colored soda ash, helps to reduce the Sand’s melting point to save energy, and limestone prevents the glass from dissolving in water.

All the ingredients are heated in a furnace to 1700 degrees Celsius or 3000 degrees Fahrenheit to make liquid sand or glass. This is poured into spinning bowls called fiberizers, which have thousands of tiny holes.

Compressed air rapidly cools down the molten glass, creating short strands of glass fibers. They are naturally white or Brown in color, but a pink polymer glue is sprayed on them, giving it the color that we know.

A conveyor belt takes these fibers to a 500 degree Fahrenheit oven, which sets the glue circular saws cut the large sheets, and an inkjet prints the manufacturer’s details and the R value on the bats. In the last stage, the bats are compacted and pushed into bags.

The most popular fiberglass manufacturer is Owens corning.

Their EcoTouch installation is available in bats, rolls, and blown in loose fill. The bats can either be unfaced faced with craft paper to control moisture transmission or a foil vapor retarder for walls connected to the exterior.

The manufacturing principles for both of these types of insulation is very similar, even though their ingredients are different. Let’s look at some of the other differences between the two.

Now, that we’ve looked at each type of insulation, let’s compare them to see which is better for sound deadening.

1. Cost

Six pieces of the 16 inch by 47 inch R30 rockwool insulation costs $61 at Low’s.

The equivalent 16 inch by 48 inch R30 fiberglass insulation costs $64 at Home Depot, but it contains eleven pieces. Stone Wool installation is almost twice the price of fiberglass.

2. Density

Stonewool is three times denser, it is also heavier. A single bat of R 30 Stone wool weighs 6.6 pounds, while an equivalent bat of R 30 fiberglass weighs 3 pounds.

Both of these insulation types operate on the insulating property of air trapped between the fibers. That’s why it’s recommended to fluff up the insulation after taking it out of the bag.

3. Sound Absorption Properties

When the bats are compressed, they lose trapped air, and the R value is drastically reduced. The loss of R value over time is called thermal drift. Stone wool, or rock wool, is stiff. If it’s compressed, it just bounces back to its original shape.

It has greater dimensional stability and lower thermal drift. Fiberglass, on the other hand, is fluffy. It doesn’t maintain its shape either vertically in walls or horizontally in attics, so its thermal drift or loss of R value over time is significant. It is marketed as an R 30 product, but that is in the actual value.

The high density of Stone Wool equals more trapped air and better sound absorption properties than fiberglass.

I have built five sound panels using STONE WOOL insulation that I bought at Home Depot for $46. The total cost of each panel, including one by four wood studs, cloth, and staples, was around $20.

4. Waterproof and Fire Resistance

Stone Wool insulation is naturally hydrophobic or waterproof. Because it is made of basalt rock, the oils added to the fibers improve water repellency. Fiberglass, on the other hand, isn’t waterproof. It can absorb water and moisture, become compacted, and lose all insulating properties.

The resistance to moisture means that Stone Wool doesn’t promote rot, corrosion, fungi, mildew, or bacterial growth. Unlike fiberglass, Stone Wool is naturally fire resistant up to 2000 degrees Fahrenheit because it has a high melting point.

If you live in an area prone to fires, it is recommended to use continuous insulation on the outside of your home like Comfort board to protect the structure of your building. Fiberglass is not as fire resistant, and it will burn. The craft paper or foil facing will make it burn even quicker.

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Installation Tips

Both stone wool and fiberglass are pretty easy to use. Stone Wool can be cut with a serrated bread knife, while fiberglass can be cut with a utility knife.

Stone Wool is easier to install because the dense, firm bats friction fit into place and don’t require any stapling, both on the walls and the ceiling. Fiberglass, on the other hand, is floppy, so it needs to be secured with staples or wire.

You must wear gloves, long sleeved shirts, and a respirator when handling both these materials. If it touches your bare skin, tiny shards of rock or glass will be embedded in it and cause rashes.

You must not inhale these fibers because they will be stuck in your lungs and your windpipe and will cause respiratory issues in the long run. Once they are installed, however, and hidden behind sheathing or drywall, there isn’t any risk to your health.

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Environmental Concerns

There are some associations that claim that mineral wool is as bad as asbestos and that the phenolic resin used in it is toxic. Despite tests showing that it isn’t, these people don’t present enough evidence to back up their claims.

The marketing for their recycled content is very tricky. Good quality stone wool is made of basalt rock with 25% to 30% recycled content.

There are other slag wool insulation brands that claim that their products have 90% recycled content. Slag wool insulation is an inferior product to basalt rock insulation, but they market it as mineral wool to deceive you, so watch out for that. Fiberglass. Insulation, on the other hand, has around 30% recycled content, mainly old windows that are crushed up.

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