Rock Wool Insulation: R-Value, Safety, and Comparison to Fiberglass

When choosing insulation for your home in Long Island, Brooklyn, or Queens, you want a solution that is energy-efficient, fire-resistant, and durable. Rock wool insulation, also known as mineral wool, has gained popularity due to its excellent thermal and acoustic insulation properties. But how does it compare to fiberglass insulation? And is there a risk of rock wool blown in insulation asbestos contamination? This guide will answer all these questions and more, providing you with everything you need to know about rock wool insulation.

What is R-Value Anyway?

R-value is a measure of insulation’s ability to resist heat flow. The higher the R-value, the better the material insulates your home. It’s important for maintaining indoor comfort, reducing energy costs, and improving efficiency. Different materials have different R-values per inch, so selecting the right insulation depends on your needs and location.

So, How Do I Know How Much R-Value I Need?

In Long Island, where winters can be cold and summers hot, having the right R-value in your insulation is critical to maintaining comfort and energy efficiency. The specific R-value you need depends on the part of your home you’re insulating.

Here’s a quick guide for our neighbors:

Attics: Aim for R-38 to R-60 to combat heat loss during chilly winters.
Walls: R-13 to R-21 is typically sufficient for Long Island homes, depending on whether you’re working with interior or exterior walls.
Floors and Crawl Spaces: Target R-19 to R-30 to keep your home warm in winter and cool in summer.

Remember, the climate on Long Island demands insulation that can handle both ends of the temperature spectrum. For the best results, consider energy-efficient materials like rock wool, fiberglass, spray foam, or blown-in insulation and consult local building codes for specific requirements. Adding up R-values when layering insulation can also help you reach the ideal level of efficiency.

Yeah, but how do I calculate r-values? Right? Easy. And remember, if you get confused, don’t understand something, or just want an expert opinion about the best insulation for your home, you can always call on Zavza Seal for a free assessment!

Check this out:

How to Calculate R-Value

Calculating the R-value of your insulation is easier than you think! Here’s a step-by-step guide:

Understand R-Value Basics:
- R-value represents how well insulation blocks heat from moving through it. Think of it as a barrier—stopping heat from passing through, whether it’s heat trying to escape your home in winter or sneak in during summer. The higher the R-value, the better the insulation keeps the heat on the right side.
Find the R-Value Per Inch:
- Check the product packaging or specifications to find the R-value per inch for the material you’re using (e.g., rock wool: 3.0 to 3.85 per inch, fiberglass: 2.2 to 2.7 per inch).
Measure the Thickness:
- Measure the depth of the installed insulation or the thickness of the material in inches.
Multiply to Get Total R-Value:
- Multiply the material’s R-value per inch by the thickness in inches.
- Example: 5.5 inches of rock wool with an R-value of 3.3 per inch = 5.5 × 3.3 = R-18.15.
Add R-Values When Layering:
- If layering different types of insulation, simply add their R-values together.
Example: A layer of R-19 fiberglass and R-30 fiberglass stacked together = R-49 total.

By understanding how to calculate R-value, you can estimate your home’s insulation effectiveness and decide if you need more.

Don’t Second Guess Your Comfort! Call Zavza Seal at (631)980-1800 Now for a Free Assessment!

Still with us? Great! Now, let’s get on with our guide and comparison:

What Is Rock Wool Insulation?

Rock wool insulation is made from molten basalt rock and industrial slag that are spun into fibers and compressed into insulation batts or loose-fill material. Unlike fiberglass, which is made from melted glass, rock wool is a denser, more rigid material that offers superior fire resistance and soundproofing. It is widely used in residential homes, commercial buildings, and industrial applications, providing excellent thermal performance and noise reduction.

R-Value of Rock Wool Insulation

As previously stated, rock wool insulation has an R-value between 3.0 to 3.85 per inch, making it one of the most effective insulation materials.

Here are the r-values of various rock wool thicknesses for batts:

3.5-inch Thick Batt: R-value of 11 to 12
5.5-inch Thick Batt: R-value of 17 to 18
8-inch thick Batt: R-value of 24 to 25

This means that rock wool provides better thermal resistance compared to fiberglass insulation, which has an R-value of 2.2 to 2.7 per inch.

Key Properties of Rock Wool Insulation:

Fire Resistance – Rock wool is a naturally fire-resistant insulation that can withstand temperatures over 1,800°F. It does not burn or contribute to fire spread, making it ideal for fire-rated walls and commercial buildings.
Moisture Resistance – Unlike traditional insulation, rock wool does not absorb water. This property reduces the risk of mold and mildew growth, making it suitable for basements, crawl spaces, and humid environments.
Soundproofing – Due to its dense fiber structure, rock wool insulation effectively blocks sound transmission, making it a top choice for multi-family homes, offices, and sound studios.

Common Applications of Rock Wool Insulation:

Exterior and Interior Walls – Used in residential and commercial construction to enhance fire resistance and thermal performance.
Attics and Basements – Ideal for preventing heat loss and moisture infiltration.
Soundproofing Insulation – Frequently installed in theaters, offices, and apartments to reduce noise transfer.

While rock wool offers impressive fire resistance and soundproofing, fiberglass insulation presents its own unique set of benefits that make it a popular alternative.

Next, let’s discuss the properties and advantages of fiberglass insulation.

What Is Fiberglass Insulation?

Fiberglass insulation is a lightweight, cost-effective option made from fine glass fibers, commonly found in batts, rolls, and loose-fill forms. It is one of the most widely used insulation materials due to its affordability, ease of installation, and energy-efficient performance.

Manufacturers create fiberglass insulation by melting glass and sand at high temperatures and spinning it into thin fibers, kind of the same way cotton candy is made. These fibers are then woven together into batts, rolls, or loose-fill material, which can be installed in walls, ceilings, and floors to enhance thermal efficiency.

R-Value of Fiberglass Insulation

As we just stated above, fiberglass insulation is widely known for its affordability and versatility, but how does it perform when it comes to thermal resistance? The R-value of fiberglass insulation ranges between 2.2 to 2.7 per inch, depending on factors such as density and type. While it may not have the highest R-value per inch compared to rock wool, it still offers sufficient thermal resistance to help maintain indoor temperatures and improve energy efficiency—and people have been using it across the world since around 1932.

For example:

3.5-inch thick batt: R-value of approximately 8 to 10
5.5-inch thick batt: R-value of approximately 12 to 15
10-inch thick loose-fill: R-value of approximately 22 to 27

Key Properties of Fiberglass Insulation:

Affordability – Fiberglass is one of the most cost-effective insulation options, making it accessible for homeowners and contractors on a budget.
Energy Efficiency – Fiberglass batt insulation has a high R-value, helping homes maintain consistent indoor temperatures and reducing heating and cooling costs.
Ease of Installation – Available in pre-cut batts and rolls, fiberglass insulation is easy to handle and can be installed by homeowners or professionals.

Common Applications of Fiberglass Insulation:

Walls and Ceilings – Used in both residential and commercial buildings for thermal efficiency.
Floors and Crawl Spaces – Helps prevent heat loss and protect against drafts.
New Construction and Retrofits – Frequently used due to its availability and affordability.

Now that we understand the basics of both rock wool and fiberglass insulation, let’s compare them side by side across key performance factors.

Rock Wool Insulation vs Fiberglass: Which One is Better?

Both rock wool and fiberglass are common choices for insulation, but they differ in various key aspects:

Thermal Performance

Rock wool has a higher R-value per inch than fiberglass, which means it provides better insulation and helps lower energy costs in the long run.

Fire Resistance

Rock wool is naturally fire-resistant and can withstand temperatures up to 1,800°F. This makes it ideal for homes and buildings in Long Island, Brooklyn, and Queens where fire safety is a priority.

Fiberglass, on the other hand, is also non-combustible but has a lower melting point and may not provide the same level of fire protection.

Moisture Resistance

Rock wool is hydrophobic, meaning it repels water and does not absorb moisture. This helps prevent mold growth and extends the lifespan of the insulation.

Fiberglass can trap moisture, which can lead to mold and mildew growth, reducing its effectiveness over time.

Sound Insulation

Rock wool has a denser structure that provides better soundproofing than fiberglass. This makes it a great option for homes in urban areas like Brooklyn and Queens, where noise pollution is a concern.

Durability

Rock wool maintains its shape and insulating properties for decades. Fiberglass, however, can settle and sag over time, reducing its effectiveness. If you’re looking for superior fire resistance, soundproofing, and moisture resistance, rock wool insulation is the better choice for homes and buildings in Long Island, Brooklyn, and Queens.

Does Rock Wool Insulation Contain Asbestos?

No, modern rock wool insulation does not contain asbestos. However, if your home was built before the 1980s, there is a chance that older insulation materials may contain asbestos. If you suspect that your home has asbestos-containing insulation, it is important to have it tested and, if necessary, professionally removed to avoid health risks.

Benefits of Rock Wool Insulation for Homes in Long Island, Brooklyn, and Queens

Energy Efficiency: Helps reduce heating and cooling costs by maintaining indoor temperatures.
Fire Protection: Non-combustible and resistant to extreme heat.
Soundproofing: Reduces noise pollution from traffic, neighbors, and construction.
Moisture Resistance: Prevents mold and mildew growth, ideal for humid climates.
Durability: Lasts for decades without sagging or deteriorating.
Eco-Friendly: Made from natural and recycled materials, reducing environmental impact.

Installation Methods for Rock Wool Insulation

Rock wool insulation can be installed in various ways, depending on your needs:

Batts and Rolls: Ideal for walls, ceilings, and floors in new construction and renovations.
Blown-in Insulation: Used for attics and enclosed spaces, filling gaps and reducing air leaks.
Rigid Boards: Used for exterior walls, roofs, and industrial applications.

If you’re in Long Island, Brooklyn, or Queens, it’s best to hire a professional insulation contractor to ensure proper installation and maximize energy efficiency.

Installation Methods for Fiberglass Insulation

Fiberglass insulation is versatile and can be installed in various ways to suit different needs and spaces. Here’s an overview of the most common installation methods with details for batts and blown-in options:

Batts and Rolls: Fiberglass batts and rolls are pre-cut sections of insulation designed for easy installation in walls, ceilings, and floors. They are ideal for both new construction and renovation projects due to their flexibility and ease of handling.
- Key Features: Available in a range of thicknesses to meet specific R-value requirements. Often faced with a vapor barrier for added moisture protection.
- Best Uses: Perfect for open cavities in walls or ceilings, where precise measurements and cutting ensure a snug fit.
Blown-In Insulation: Blown-in fiberglass insulation is a loose-fill material installed using special equipment, making it an excellent choice for hard-to-reach areas or irregularly shaped spaces.
- Key Features: Offers great coverage by filling gaps and crevices, reducing air leaks. Works well in spaces with existing insulation needing reinforcement.
- Best Uses: Ideal for attics, enclosed walls, and retrofits, where complete and even coverage is essential for efficiency.

For the best performance, proper installation is critical, especially for maintaining the material’s R-value and preventing gaps. Homeowners in Long Island, Brooklyn, or Queens should consider hiring professional contractors to ensure precision and energy efficiency. Let me know if you’d like to expand on these methods further!

Insulation Solutions Tailored To Your Needs

At Zavza Seal LLC, we specialize in providing top-of-the-line insulation services to enhance your home or business’s energy efficiency, comfort, and protection. Our experienced team is dedicated to delivering customized solutions with precision and care, helping you create a space that feels just right.

Our Insulation Services Include:

Fiberglass Insulation: Fiberglass insulation offers a budget-friendly option for thermal efficiency and consistent indoor temperatures.
Spray Foam Insulation: Spray foam insulation is perfect for sealing hard-to-reach areas, ensuring maximum energy savings and moisture control.
Blown-In Insulation: Blown-in insulation is designed for easy application in attics and walls, providing even coverage and superior insulation performance.
Batt Insulation: Batt insulation offers a reliable and cost-effective choice for new constructions and retrofits alike.

No matter the insulation type you need, our experts will guide you toward the best solution for your property. Let us help you lower energy costs, reduce noise, and increase your home’s overall comfort.

Start Saving Today With Expert Insulation – Contact Zavza Seal LLC Now!

Why Choose Zavza Seal LLC For Your Insulation Needs

At Zavza Seal LLC, we don’t just install insulation—we provide long-term solutions that ensure energy efficiency, comfort, and peace of mind. With a 5-star Better Business Bureau rating and a steadfast commitment to quality and customer satisfaction, we’re the trusted choice for insulation services in Long Island, Brooklyn, Queens, and The Bronx.

Benefits Of Choosing Zavza Seal LLC:

Experienced Team
High-Quality Materials
Energy Efficiency
30-Year Warranties

Let us help you transform your home or business with reliable insulation solutions backed by unmatched expertise and service guarantees.

Rock Wool vs Fiberglass Insulation: Final Thoughts

For homeowners in Long Island, Brooklyn, and Queens, rock wool insulation is a top choice for energy efficiency, fire safety, and soundproofing. With its superior R-value, moisture resistance, and long lifespan, it is an investment that pays off in comfort and savings.

If you’re considering installing rock wool insulation, Zavza Seal LLC provides expert insulation services tailored to your home’s needs. Contact us today for a consultation and improve your home’s energy efficiency and comfort!

Common Questions About Rock Wool Insulation

1. Is Rock Wool Insulation Safe?
Yes, rock wool is safe to use and does not contain harmful chemicals. However, like fiberglass, it can cause skin irritation during installation. Wearing protective gear such as gloves and masks is recommended.

2. Does Rock Wool Insulation Prevent Mold?
Yes, rock wool is moisture-resistant and does not support mold or mildew growth, making it an excellent choice for humid climates.

3. Can Rock Wool Be Used for Soundproofing?
Yes, rock wool provides excellent sound absorption and is commonly used in recording studios, home theaters, and apartments to reduce noise transmission.

4. How Long Does Rock Wool Insulation Last?
Rock wool insulation is extremely durable and can last 50 years or more without losing its insulating properties.

5. Is Rock Wool Better Than Spray Foam Insulation?

It depends on the application. Spray foam insulation has a higher R-value per inch but is more expensive and requires professional installation. Rock wool offers better fire resistance, soundproofing, and eco-friendliness at a lower cost.

Rock Wool Insulation: R-Value, Safety, and Comparison to Fiberglass