Welcome aboard the world of stone-wool insulation! If you’re in the business of building envelopes, energy efficiency, acoustic control or fire protection, you’ve likely come across rock wool (or stone wool) and wondered “who actually makes it in the USA?”.
In this article we’ll dive into the top 5 rock wool manufacturers in the USA, take a look at their key offerings, strengths, and what makes them stand out among the many suppliers of rockwool insulation. Whether you’re a contractor, specifier, procurement manager or simply doing your homework, you’ll leave with a clearer map of the supply-chain of this high-performance insulation material.
Who makes rock wool insulation in the USA?
Below is a table summarizing five leading players in the U.S. market, their main products, strengths, and minimum order considerations (where publicly available). This will help you compare at a glance key rock wool insulation suppliers, and learn about their factories and product lines.
| Manufacturer | Main products | Strengths & differentiation | MOQ / Notes |
| ROCKWOOL North America | Stone wool batt and board insulation (e.g., Comfortboard®, Cavityrock®, Rockboard®) | Non-combustible, excellent acoustic/thermal performance, U.S. factory presence (Byhalia MS; Ranson WV) | Factory scale – large volumes; typical project-orders rather than very small MOQ |
| **Johns Manville Mineral Wool Division | Mineral wool batts, boards for exterior cavity walls, rain-screen, fire/sound block applications | Long history, strong performance specs (e.g., melt point > 2000°F) | Established manufacturer; order size flexible via distribution network |
| **Knauf Insulation (Rock Mineral Wool line) | Rock mineral wool slabs and boards for building envelope, industrial applications | Global scale, broad product range; U.S. operations among many countries | MOQ varies by product and region – project-based |
| **Thermafiber (owned by Owens Corning) | Mineral wool insulation boards (e.g., RainBarrier®) for fire and exterior wall systems | Specialist in fire-containment and commercial systems, part of major U.S. building-materials firm | Established supply chain; quantity depends on specification |
| **American Rockwool Manufacturing | Loose-blown rock wool, industrial rock wool (Cryowool™), horticultural rock wool (Hortiwool™) | Emphasis on chemical-free production, sustainability, industrial applications beyond just building envelope | Flexibility in application; ask directly about MOQ for non-standard use |
ROCKWOOL North America
Background & Factory Footprint
- ROCKWOOL is a global leader in stone wool insulation, and its North American business includes manufacturing in the USA (e.g., factory operations in Ranson, West Virginia)
- Their U.S. operations are positioned to supply contractors and specifiers domestically, serving as one of the major rockwool factories in the region.
Main Products & Applications
- Comfortboard® 80 and 110: rigid stone wool boards for exterior continuous insulation.
- Cavityrock®: semi-rigid board for cavity wall/rainscreen systems.
- Safe’n’Sound® and batt products: interior fire/acoustic insulation.
Why choose them (as a rockwool insulation supplier)?
- High performance: non-combustible, high temperature resistance, good acoustics.
- Domestic manufacturing → local lead-times, possible logistical advantage in U.S.
- Strong technical support and documentation for specifiers and architects.
Considerations
- As a large manufacturer, pricing may reflect premium performance.
- Minimum order quantities may be higher; for small-scale or custom sizes one may need to coordinate with distributor rather than direct factory.
Johns Manville (Mineral Wool Division)
Johns Manville produces mineral wool insulation (rock-based) for building envelope, mechanical insulation and more.
The products are inorganic, non-combustible and designed for demanding applications.
Product Highlights
- CladStone™ Water & Fire Block: exterior cavity/rainscreen insulation boards made from volcanic rock fibers.
- Sound & Fire Block®: high density batts for interior walls/floors with fire-resistance emphasis.
Strengths
- Proven performance specs: e.g., flame spread index of 0, smoke development of 0 in some products.
- Reputation in the U.S. as an established insulation manufacturer; good availability of documentation and distribution.
Things to check
- While strong in the U.S., for custom board sizes or specialty use check distributor stock/lead-time.
- For extremely high-volume projects, negotiate MOQ and pricing terms ahead.
Knauf Insulation (Rock Mineral Wool line)
Knauf, founded in the U.S. (Shelbyville, Indiana) but global in reach, offers rock mineral wool among its insulation ranges.
Although some production may be outside the U.S., they serve the U.S. market as one of the suppliers of rockwool insulation.
Product Benefits
- Rock mineral wool slabs: high fire resistance, excellent acoustic and thermal performance.
- Range covers building to industrial to OEM solutions (e.g., green roofs, process industry).
Why pick Knauf?
- Broad specialization across insulation markets means they understand different application contexts.
- Global scale may bring efficiencies and availability of custom solutions.
Notes
- Ensure the specific product is manufactured or stocked in the U.S. (or can be delivered economically).
- Confirm product certifications and factory origin if “Made in USA” is a requirement for your project.
Thermafiber (owned by Owens Corning)
Thermafiber is a brand / division specializing in mineral wool insulation boards, especially for fire containment and exterior walls.
Under the ownership of Owens Corning, they benefit from strong U.S. presence and distribution.
Product Focus
- Boards such as RainBarrier®: continuous mineral wool insulation boards for exterior façade and rainscreen systems.
- Insulation designed for commercial & industrial building envelope systems with fire and thermal performance.
Strengths
- Deep experience in fire-rated systems and commercial construction.
- Good integration in U.S. supply chains and building-materials networks.
Considerations
- Because of focus on commercial/industrial, smaller residential or specialty orders may have less flexibility.
- As always, check lead-times and MOQ for board thickness, size and facer options.
American Rockwool Manufacturing
American Rockwool Manufacturing markets rockwool insulation (loose-blown, industrial, horticultural) and emphasizes chemical-free processes.
This makes them somewhat different from purely residential batts/boards manufacturers; they cover building envelope but also industrial/horticultural use.
Key Products
- Premium Plus™ Loose-Blown Rockwool Insulation – for residential/commercial cavity fill.
- Cryowool™ for industrial high-temperature/pipe insulation.
- Hortiwool™ – rockwool media for horticulture/hydroponics.
Why choose them?
- Unique offering: if your project spans industrial, horticultural or non-typical insulation use, they add breadth.
- Emphasis on sustainability and chemical-free manufacturing may appeal for LEED or green building spec.
Considerations When Choosing a Rock Wool Insulation Supplier
When you’re evaluating rockwool insulation suppliers or comparing rockwool factories for your project, here are some key points to keep in mind:
Factory location & lead time
- Choosing a manufacturer with U.S.-based production (or nearby regional distribution) can reduce shipping time, customs risk, and logistics cost.
- Even domestic factories may have shipping constraints for oversize boards or special facer options, so clarify early.
Minimum order quantity (MOQ) & stock-availability
- Some manufacturers primarily serve large commercial projects; if you have smaller scale project, check if they support smaller MOQs or if you must go through a distributor.
- Standard board sizes (thickness, facing, dimensions) are often stocked – custom sizes may require factory run and longer lead time.
Product performance & certification
- Confirm that the product meets required specifications (e.g., non-combustibility, R-value, sound transmission, moisture resistance). For example, Johns Manville’s mineral wool batts boast melt point > 2000°F.
- Review certifications, performance data sheets, fire test results, and ensure suitability for your application.
Sustainability & manufacturing credentials
- Many projects now require materials from manufacturing with environmental credentials, recycled content, low-emissions. For example, American Rockwool emphasizes chemical-free manufacturing.
- Domestic manufacturing may align better with local sourcing goals and reduce carbon footprint from shipping.
Technical & logistical support
- Ensure the supplier provides technical support (spec sheets, installation guides, training) and has a reliable distribution network.
- For large orders, ask about factory capacity, scheduling, and the ability of the rockwool factory to accommodate your timeline.
Frequently Asked Question
Q: Who makes rock wool insulation in the USA?
A: In the U.S., several major manufacturers produce rock or stone wool insulation via their domestic facilities or regional operations. The table above lists five of the most prominent: ROCKWOOL North America, Johns Manville, Knauf Insulation (rock mineral wool), Thermafiber (Owens Corning) and American Rockwool Manufacturing. These companies serve as leading rockwool insulation supplier options and operate factories or supply chains capable of servicing U.S. projects.
When evaluating, check for:
- Whether their manufacturing occurs in the USA or the product is imported.
- Whether the product you specify is stocked or requires a custom run.
- Whether the facility qualifies as one of the relevant rockwool factories with production scale for your needs.
- Whether they operate as direct manufacturer or via a distributor (which still qualifies them among the major suppliers of rockwool insulation).
RPower Helps You
Choosing the right rock wool manufacturer is only the first step—having a trusted insulation partner by your side is what truly elevates your project. That’s where RPower comes in. As a professional supplier specializing in thermal insulation materials for industrial, construction, and high-temperature environments, RPower provides high-quality products, consistent performance, and reliable global delivery.
Our capabilities extend beyond simple sourcing. We support clients with custom engineering advice, OEM/ODM service, bulk supply solutions, and strict quality control, ensuring every order meets international standards. Whether you need rock wool boards, industrial thermal insulation, or tailored project solutions, our team helps streamline your procurement process from start to finish.
If you’re looking for a dependable partner—not just a vendor—visit us at chinathermalinsulation.com and discover how RPower can support your next insulation project with efficiency, expertise, and truly responsive service.
