Tag Archives: soundproofing

Comparing Rockwool and Fiberglass Insulation

Comparing Rockwool and Fiberglass Insulation  

Fiberglass insulation has long been a popular option for slowing heat transmission through building walls and ceilings. While it may have an added benefit of creating a fire-resistant layer between interior and exterior walls, fiberglass still may not measure up to Rockwool’s natural abilities. Like fiberglass, Rockwool is an insulation material regularly used in residential, commercial, and industrial buildings.

Rockwool can be differentiated from fiberglass by comparing heat retention, fire resistance, moisture resistance, and soundproofing capabilities. 

Rockwool insulation’s manufacturing processes helps to explain true fire-resistant potential of this product. It’s composed primarily of basalt rock and a recycled steel-making byproduct known as slag. These components are superheated, allowing them to liquefy and mix together into a lava-like liquid. In order to melt these substances, temperatures must exceed 2,900 degrees Fahrenheit.

This mixture is then blown into a large spinning chamber designed to stretch superheated liquid into fibers. These fibers are then gathered together and compressed into a mat, then cut into slabs of Rockwool insulation.

By creating Rockwool through this process, all organic matter is eliminated, greatly increasing finished product’s mold- and mildew-resistance.

Confusion about recycled material amounts used to make Rockwool insulation can mostly be attributed to statistics about mineral wool insulation in general. Rockwool is a brand-specific type of mineral wool insulation so popular its name became synonymous with mineral wool. Brand-specific Rockwool insulation is typically between 16 to 40 percent recycled materials. Department of Energy has stated mineral wool insulation contains an average 75% recycled materials. Department of Energy’s estimate is hard to back up as they make a distinction between standard ‘rock wool’ insulation and ‘slag wool’ insulation, but don’t note difference in recycled material amount for each product. Also, this is a perfect example where ‘Rockwool’ brand name being used in place of generic material name, blurring lines between products.

In general, it can be derived recycled material amount in Rockwool insulation is not precise because it ultimately depends on specific product. Rockwool insulation may only have between 16 to 40 percent recycled material, while slag Rockwool insulation can be made with up to 75 percent recycled material.

Both fiberglass and Rockwool are effective at keeping buildings cool in summer and warm in winter, but specific thermal efficiency of these materials favors Rockwool. While fiberglass insulation is capable of offering an R-value of about 3 to 3.2 per inch of insulation, Rockwool has an R-value between 4 to 4.2 per inch of insulation.

Fiberglass insulation also may lose some thermal efficiency over several years if it begins to degrade. Due to construction methods and materials used to make Rockwool insulation, its thermal performance remains stable over a building’s lifetime. Rockwool does cost more per square foot than fiberglass insulation.

As noted previously, Rockwool insulation is formed from literal rocks and steel slag and must be heated beyond 2,900 degrees Fahrenheit in order to mix component materials and create this highly effective insulation. With this in mind, it makes sense mineral wool products in general can resist fire, flames, and heat up to 1,400 degrees Fahrenheit, while some Rockwool products are capable of resisting temperatures up to 2,150 degrees Fahrenheit without melting, smoking, or catching on fire.

This impressive heat-resistance is ideal for buildings because it forms a fire-resistant barrier between building interior and exterior, between rooms, and even between floors, slowing fire spread. It should be noted fiberglass insulation is also highly heat-resistant, though it begins to melt at about 1,100 degrees Fahrenheit.

Rockwool’s durability is difficult to dispute, given it is capable of retaining its thermal efficiency over a building’s entire lifetime without degradation in its R-value. This is due to materials used to make Rockwool insulation, including rock and steel slag, both known for having a high level of durability and natural resistance to decay and corrosion.

However, Rockwool’s durability isn’t limited to material’s heat retention quality. Impressive water-resistance, mold-resistance, mildew-resistance, and fire-resistance also contribute to Rockwool insulation’s durability and capabilities. 

Some people may not appreciate Rockwool insulation’s heftiness because it does tend to be thicker than fiberglass insulation, but this helps to slow heat transmission and it has an added effect of slowing sound waves. As sound waves attempt to move through Rockwool material, they are slowed and sometimes completely blocked, creating built-in soundproofing.

While insulation thickness helps to block noise, it is Rockwool insulation’s density providing soundproofing. Fiberglass insulation has a density of about 0.5 to 1.0 pounds per cubic foot, allowing it to reduce sound by 4 to 10 decibels. Rockwool insulation has a density of around 1.7 pounds per cubic foot, capable of consistently dampening sound by 10 to 15 decibels.

Rockwool’s construction and composition make it ideal for rooms prone to high levels of humidity, like bathrooms or kitchens. Rockwool insulation’s moisture-resistant and vapor-permeable qualities mean any liquid water will drain away from insulation instead of soaking into it, while gaseous water vapor will pass through without dampening material.

Additionally, Rockwool insulation is inorganic, so it makes a poor medium for mold and mildew to grow as there is nothing for them to use for energy. In fact, Rockwool products are also tested and certified as resistant to fungal growth, reducing chances users will open up a wall and find a dangerous biological problem waiting for them.

QuietRock – The Sound Dampening Sheetrock Solution

QuietRock – Sound Dampening Sheetrock

When my wife and I designed our pole building home in South Dakota, one of our considerations was to isolate (for sound) as much as possible the master suite from the living areas of the rest of the house.  We put a large pool table in the center of an adjoining room and wanted kids (grown now) and grandkids to be able to access it at any hour of the day, without fear they were disturbing our beauty sleep.

In our case, we used interior walls which were framed with 2×8 top and bottom plates; with offsetting 2×4 studs (the studs on the interior and exterior walls are not aligned). To further deaden sound, we installed a layer of drywall between the studs, insulated both with fiberglass insulation and then used 5/8” drywall on both exterior sides.

While our solution has been effective, I’ve since found there may very well have been a more practical solution, which would not have used up so much floor space – caused by the width of the double walls.

QuietRock SheetrockQuietRock is a brand of internally damped drywall panel manufactured in the United States by Quiet Solution (aka Serious Materials and Serious Energy). It is designed to provide high levels of sound attenuation between rooms.

QuietRock uses a damping technique called constrained-layer dampening (CLD). QuietRock panels use several tuned constrained-layer systems to create a higher ability to damp vibrational (and therefore acoustic) energy. In essence, the panel does not “want” to vibrate due to stress and strain caused by the damping method. Acoustic energy ends up dissipating as small amounts of heat (which cannot be heard).

Sound attenuation is measured using tests known as ASTM E90 and ASTM E413 to achieve a single sound-transmission-class (STC) rating. QuietRock is one of a class of soundproof drywall products that, according to independent lab tests and field reports, may add 15 to 20 STC points in comparison to standard drywall.

Most of QuietRock panels should have no effect on WiFi or cellular in a pole building. There are a few exceptions to this. Two panels, the QuietRock 530 and QuietRock 545 do contain a layer of steel in the panel which may interfere with WiFi or cellular signals.

QuietRock cannot be used alone for fire rated assemblies. For a panel to be considered fire rated, it must be tested by UL laboratories and pass the fire test (typically either a 1 or 2 hour rating), for the specific assembly. Individual UL fire tests are conducted for specific assemblies and for a product to be considered “fire rated” for a particular assembly it must be included in and pass the specific test. Once an assembly and set of materials is included in a test pass, they are given a “UL Design Number” indicating those materials are approved for the stated test for only the particular assembly. QuietRock has not been tested on any floor/ceiling assemblies as there are too many floor/ceiling assemblies to practically test and each test is expensive to conduct. In order to get a 1 hour rated floor/ceiling assembly to pass, one layer of 5/8″ Type X drywall would need to be added along with the QuietRock layer.

Looking for peace and quiet in a new pole barn?  If so… QuietRock may prove to be a product worth investigating further.