A Comprehensive Guide to Rockwool Insulation

What is Rockwool Insulation Made Of?

Surprisingly, just like the name sounds, Rockwool is made from natural rock materials that have been spun into wool-like fibers. The rock happens to make a dense, flexible insulation product that's easy to work with.

Let’s break down exactly what Rockwool products are and their reputation as a preferred material for insulation.

The primary component of Rockwool insulation is rock—specifically basalt and diabase. These volcanic rocks are well known for their durability and thermal resistance. Manufacturers melt the rocks at extremely high temperatures to form molten lava.

Manufacturers spin the molten rock using high-speed spinning tools into very fine wool-like fibers. Binders and oil are added to the fibers to make them stick together. The fibers are felted together into a mat that is compressed into insulation products: rolls, bats, and loose-fill insulation.

The resulting product, Rockwool, is dense and durable with excellent thermal resistance. It significantly slows the transfer of heat in your home, which helps keep temperatures comfortable and consistent. By keeping your house environment steady, you'll reduce energy consumption and costs associated with heating and cooling.

Benefits of Rockwool Insulation

So why choose Rockwool insulation? Is it better than other types of insulation? What are the benefits?

When you select any type of insulation, it's important to familiarize yourself with the different options on the market. Rockwool insulation is an excellent choice in certain cases, but it's essential that you choose the right thickness and density to hit the R-value for your application (we'll explain).

Rockwool insulation has some unique benefits that make it a popular option for many circumstances. Here are some of the key advantages:

Superior Thermal Performance

Because Rockwool is made of densely compact fibrous strands, it traps air. This feature results in better thermal insulation by minimizing heat flow. If you’re tired of adjusting the thermostat (and paying for the resulting heating bills), Rockwool can help you enjoy a consistent temperature in your home.

Exceptional Fire Resistance

Rockwool is made from lava rock—it’s built to withstand temperatures exceeding 1,000°C (1,832°F) without melting or giving off toxic smoke fumes. In the event of a fire,  mineral wool insulation prevents the spread of flames and gives more time for a safe evacuation.

Great Sound Absorption

Sleep soundly with Rockwool insulation. The product significantly reduces noise transmission between rooms and from the outside. It improves the room's acoustical performance, too. Acoustic insulation is ideal for homes, especially bedrooms and home offices. It’s also a good choice for multi-residential buildings and commercial applications where sound is a concern.

Durable

Unlike many types of insulation, Rockwool will not degrade over time. It stands up to mold, mildew, and rot. Rockwool will likely outlast many of the other building materials and components in a structure. The long lifespan makes it an especially cost-effective insulation option.

Moisture Resistant

Rockwool is uniquely breathable. It allows water vapor to pass through while simultaneously being water-repellent. Moisture won’t accumulate inside the insulation, which prevents mold and mildew growth. It's also an excellent choice for naturally damp environments.

Easy to Install

One of the reasons Rockwool is such a popular product (aside from all the excellent features above) is that it’s easy to install. It’s available in many different formats, including batts and rolls, which you can tailor to any needed configuration. Semi-rigid batt insulation works well for many different applications. No matter what type of Rockwool you use, it's very important to wear protective gear.

Rockwool R-Value

As we mentioned above, it's essential to choose the right R-value when selecting any type of insulation. What's an R-value, and what is the R-value of Rockwool insulation?

We’re glad you asked! R-value is a marker of insulation’s resistance to heat flow. The higher the R-value, the better the material insulates. The target R-value varies between climate zones. In other words, in the cold upper Midwest, you may need a higher R-value insulation than in the sunny Southwest.

Rockwool insulation has a typical R-value between R-3 and R-4.1, but it will depend on the specific density and product. A better R-value will help your space retain heat in the winter and stay cool in the summer. It will also help you cut down on those high utility bills.

Most packaging indicates the R-value of an insulation product. It's important to check with local building codes to ensure you choose the right R-value for your locale. Other factors may also play into the R-value, including the age and thickness of the insulation product, the presence of any damage, and the type of insulation material.

Rockwool Insulation vs. Fiberglass Insulation

Fiberglass insulation is also a very common option for home insulation. You’re likely familiar with the cotton candy-like fiberglass in shades of pink and yellow. This type of insulation has been used for many years, and in many cases, it does a good job.

In their own right, each material is better suited for certain applications. Each has unique properties. However, in a side-by-side comparison of Rockwool insulation versus fiberglass insulation, here’s how the two stand:

Rockwool Insulation

Pros:

• Thermally efficient: Because Rockwool is very dense, it has a higher R-value per inch compared to fiberglass. This means it offers better insulation per inch of thickness.

• Fire Resistant: Rockwool has excellent fire-resistant capacity, withstanding temperatures over 1,000°C. It is non-combustible and adds fire protection to buildings.

• Absorbs sound: Rockwool has excellent sound absorption capabilities, reducing noise transmission through ceilings, walls, and floors.

• Resists moisture: Rockwool has the unique qualities of being vapor-permeable and water-repellent. It allows your home to "breathe" while preventing mildew and mold.

• Sustainable: Because Rockwool is made from natural and recycled materials, it's considered environmentally friendly. It also outlasts many other building materials.

Cons:

• Higher Cost: Generally, installing Rockwool is more expensive initially than installing fiberglass insulation. However, long-term cost savings may mean a better ROI overall.

• Requires Safe Handling: As with fiberglass, Rockwool requires handlers to wear skin and respiratory protective gear. Rockwool can be more irritating than other insulation types.

• Heavier Weight: Rockwool is heavier than fiberglass. Ordinarily, this isn't a significant issue, but in certain spaces, the weight of insulation may be a consideration.

Fiberglass Insulation

Pros:

• Cost-Effectiveness: Installing fiberglass insulation is usually less expensive than Rockwool. If the initial budget is a concern, fiberglass may be a better choice.

• Easy-to-Install: Fiberglass is lightweight, easy-to-cut, and simple to install. It fits nicely in most standard joist and stud spaces. Like Rockwool, it's available in rolls and batts, which make it easy to handle.

• Energy Efficient: Fiberglass, like Rockwool, offers good thermal insulation. While the R-value of Rockwool is slightly higher, fiberglass offers a comparable range. It is the go-to choice for many applications where energy efficiency is a priority.

Cons:

• Lower Fire Resistance: Like Rockwool, fiberglass insulation is non-combustible, but it doesn’t offer the same superior fire resistance that Rockwool does. Fiberglass will melt at very high temperatures.

• Less Sound Absorption: Fiberglass isn’t as ideal for soundproofing applications and sound insulation. It’s less dense than Rockwool and doesn’t absorb sound as effectively.

• Requires Safe Handling: Both Rockwool and fiberglass irritate the skin, eyes, and respiratory system. No matter which option you choose, proper safety gear is paramount.

Best Places to Use Rockwool Insulation

If you’re leaning toward mineral wool insulation, it’s important to know the best uses for Rockwool. Not all areas of your home may need Rockwool insulation—it depends on your needs for the space. Rockwool is good for new residential construction as well as DIY home insulation replacement and updates.

Rockwool Soundproofing Insulation

Rockwool is particularly useful for soundproofing and sound-sensitive applications. The dense, fibrous structure readily absorbs and cuts the transmission of sound waves. It's an excellent insulation choice for walls, floors, and ceilings where sound may be a concern. Rockwool is the go-to for home theaters, music studios, and multi-family dwellings. The sound-absorbing properties minimize noise transfer and create a quiet, peaceful space.

Rockwool Exterior Wall Insulation

Rockwool is a good selection for insulating exterior walls. Because of its moisture resistance and breathability, it makes a very effective barrier against heat loss and gain. Its water tolerance helps prevent water-related damage while still allowing for the regulation of humidity and condensation. Rockwool helps thwart mold and mildew growth (and resulting rot) in damp environments.

Rockwool Attic Insulation

Your attic is one of your home's most crucial points of heat loss. Insulating your attic is a pretty easy DIY project for homeowners. Using Rockwool will help you improve your home's efficiency and reduce the workload on your heating and cooling systems. It also adds another layer of fire safety for your home.

How to Install Rockwool Insulation

Installing Rockwool insulation is a simple process, but you must follow handling instructions and safety precautions. This project requires some attention to detail, so put plenty of time on your calendar before tackling Rockwool insulation installation.

Tools & Supplies:

• Insulation knife or serrated blade

• Tape measure

• Stapler

• Safety gear, including gloves, goggles, and a respirator

• Rockwool insulation

• Sealant or foam sealer

• Vapor barrier

Take Safety Precautions

With all DIY projects, safety is one of the most critical factors. It's especially important when handling Rockwool insulation, which can irritate your skin, eyes, and respiratory system. Wear long sleeves and long pants when working with Rockwool, and ensure the space has plenty of ventilation.

It's also important to handle the Rockwool gently. Compressing and squishing the insulation can damage its effectiveness (and lower the R-value). Use a sharp insulation knife to cut the pieces cleanly. Measure carefully to ensure a snug fit that avoids both gaps and compression.

Rockwool Installation Process

• Step 1: Prepare the Space: Measure and prepare the area where you will install the insulation. Clear the area of all debris. If you're working in an attic or a basement, move items to one side while you work so you have a clear, open space. Make sure the space is well-ventilated and dry.

• Step 2: Cut to Size: Measure and cut the Rockwool to fit the spaces between the studs, joists, or rafters of your wall, ceiling, or floor. Slightly oversize the cuts (by about ¼ to ½ inch) to create a friction fit to eliminate gaps.

• Step 3: Fit in the Insulation: Press the insulation into place, ensuring a snug (but not compressed) fit. The material should fill the cavity, touching all sides.

• Step 4: Seal the Gaps: Use sealant or foam to fill any small gaps around the insulation. Make sure you don’t see any areas for air leaks.

• Step 5: Cover with Vapor Barrier: Depending on where you’ve installed the insulation, you may need to cover it with a vapor barrier and/or drywall. Check your local building codes and the manufacturer’s instructions. It’s especially important to cover the insulation in any exposed areas of your home.

Shop Rockwool Insulation at Do it Best

We carry Rockwool insulation at Do it Best! Thanks to its reliability and reputation, Rockwool is one of our most popular insulation types. If you're looking for an ideal insulation solution, explore Rockwool for your home.

Rockwool has a high R-value that is suitable for many climates and situations. It's available in several styles, including roll and batting insulation options. It's a great choice for your attic, basement, or any other area of your home where you're seeking excellent insulation protection. Rockwool stone wool insulation is water resistant and gives you peace of mind that your home will be protected against bacterial growth and other moisture-related concerns. 

Rockwool provides excellent noise reduction. Adding a continuous layer of insulation to floors or walls can improve a room's acoustic performance. Rockwool roof insulation can thwart the spread of fire and provide additional safety for your home. 

Homeowners can install Rockwool insulation themselves, but it's crucial to take all safety precautions. Handle Rockwool with gloves, protective eyewear, a respirator, and long sleeves. Follow all manufacturer's instructions to avoid irritation from the product.

If you’re considering saving money by DIY-ing your home insulation, Rockwool is an excellent choice. Explore our insulation supplies and information at Do it Best!