A recent USG blog post and comprehensive white paper raised important concerns about magnesium oxide (MgO) panels, warning specifiers about moisture issues, quality control problems, and questionable fire performance claims. Here's the thing: they're absolutely right about many well-known products in the market.
But they're missing a crucial part of the story.
USG's concerns about the MgO category aren't unfounded. Their white paper provides concrete evidence of serious problems with specific products in the market. In 2020, USG commissioned independent third-party testing of four major MgO brands using ASTM E136 standards for noncombustibility:
The results were damning. All four brands failed the noncombustibility test.
The tested panels reached maximum temperatures far exceeding the 780°C (1436°F) failure threshold:
Even more telling, all four products exceeded the 3% total organic carbon content that typically indicates combustible material:
Beyond the fire performance failures, USG also identified the broader issues affecting the category:
Moisture and Corrosion Risks: Products using magnesium oxychloride (MOC) formulations, especially poorly manufactured ones, can absorb excessive moisture leading to "weeping" and corrosion of metal fasteners and framing.
Quality Control Challenges: Most MgO panels sold in North America are imported from overseas manufacturers with inconsistent quality control practices and limited oversight.
Supply Chain Concerns: Without uniform manufacturing standards, even panels from the same supplier can vary significantly in composition and performance.
These are real issues that every architect, specifier, and builder should understand. The question isn't whether these problems exist. The question is: how do you avoid them?
Not all MgO panels are created equal. MAXTERRA® wasn't developed to be another commodity board that makes promises it can’t keep. It was engineered specifically to address the performance and reliability issues that plague this category.
While many problematic MgO products use magnesium oxychloride (MOC) formulations, MAXTERRA® uses magnesium oxysulfate (MOS) chemistry. This isn't just a technical detail. It's the fundamental difference that eliminates the moisture absorption and corrosion risks associated with unreacted magnesium chloride.
The MOC formulation issues referenced in the USG white paper surrounding corrosion potential and moisture absorption due to unreacted magnesium chloride are inherently eliminated with our MOS formulation.
USG is correct that many MgO manufacturers incorrectly claim noncombustibility. The temperature rise issues during ASTM E136 testing that affect other products aren't present with MAXTERRA® structural products. Both interior and surface temperatures stay below the required threshold for the duration of the test.
This distinction is becoming even more critical. The test standard for non-combustible materials (ASTM E136) has been clarified in the 2024 IBC, meaning some MgO products will no longer be considered non-combustible. Products currently classified as non-combustible may be reclassified by certification agencies by January 2026.
MAXTERRA® meets the updated 2024 IBC standards for noncombustibility. This isn't a claim. It's verified performance data.
It's one thing to make claims about performance. It's another thing to have the testing and certifications to back up your claims. All MAXTERRA® products are third-party certified by ICC-ES, requiring comprehensive review of our quality control procedures and regular follow-up inspections to ensure consistent formulation, processes, and products over time.
This is the exact same certification program USG uses for many of their own products, including their STRUCTO-CRETE product line.
When you compare the certification reports for MAXTERRA® Structural Floor Panels (ESR-5194) and USG STRUCTO-CRETE (ESR-1792), you'll find they include the same acceptance criteria testing data. But MAXTERRA® actually meets additional acceptance criteria beyond what STRUCTO-CRETE achieves, including AC367, AC386, AC376, and AC378.
MAXTERRA® doesn't just meet the baseline AC386 industry standard. Our products hold application-specific certifications for structural floor sheathing (AC318, AC319, AC367), wall and ceiling applications (AC376, AC378), and shear wall performance (AC269.1, AC269.2).
MAXTERRA® is the only MgO panel with a verified Environmental Product Declaration (EPD) for the North American market. This level of environmental transparency represents another layer of third-party verification that goes beyond basic performance testing. The achievement of this verified EPD demonstrates our commitment to transparency and accountability that commodity boards simply don't offer.
The concerns USG raises highlight exactly why MAXTERRA® exists. We recognized early on that the MgO category needed a product that could deliver consistent performance backed by rigorous testing and certification.
While others compete on price with commodity boards of questionable quality, we've focused on engineering a category changer that specifiers can trust. The difference shows up in our chemistry, our certifications, our quality control, and our transparency.
USG's white paper should serve as a wake-up call for anyone considering MgO panels. The independent testing they commissioned revealed that major brands making noncombustibility claims simply don't deliver on those promises. Don't assume all products in this category perform the same way. Ask the hard questions:
These aren't technical details that only engineers care about. They're the difference between a product that performs as expected and one that creates problems down the road.
The MgO category has tremendous potential to deliver fire resistance, structural performance, and moisture management that conventional materials can't match. But realizing that potential requires products engineered to deliver on those promises consistently.
MAXTERRA® doesn't just claim performance. It proves it. With MOS chemistry that eliminates moisture and corrosion concerns. With ICC-ES certification that validates every performance claim. With environmental transparency that demonstrates accountability.
Because when it comes to building materials, making claims is easy. Backing them up is where most products fail.
For specifiers who demand more than marketing promises, MAXTERRA® delivers the data, certifications, and proven performance that turn potential into reality.
Ready to experience the MAXTERRA® difference? Request a free sample and see the quality for yourself.
Yes. MAXTERRA® is ideal for multifamily projects, with performance advantages across Type I through Type V construction. Its certified fire resistance makes it especially valuable in Type I and II, where noncombustible materials are required, and in Type III, where MAXTERRA® enables efficient fire-rated wall assemblies without the use of FRT wood or exterior gypsum.
The combination of structural performance, moisture resistance, and fire safety helps developers meet code, streamline schedules, and maintain design flexibility.
Absolutely. MAXTERRA® Structural Floor Panels are ICC-ES certified for use with cold-formed steel framing, making them the only MgO panels on the market with this level of verified performance. Evaluated under AC318 and AC319, they provide certified strength, span ratings, and diaphragm performance in CFS floor assemblies.
If you're building with cold-formed steel, MAXTERRA® delivers the industry's most advanced, code-approved MgO flooring solution.
We like to say: It's not just the cost of the board; it's the cost of the build. MAXTERRA® is a premium product that's competitively priced with commodity boards, but the real difference shows up on the job site. Our panels are engineered for smarter, more efficient installs. That means less need for added fasteners, extra support, or over-framing that other products often require. The result is fewer materials, faster schedules, and a lower total cost of construction. It's not just cost-effective. It's construction-effective.
The key difference is moisture behavior. MOC (magnesium oxychloride) panels can absorb moisture from humid environments and cause corrosion when in contact with metal fasteners and framing. MOS (magnesium oxysulfate) chemistry, used in MAXTERRA®, eliminates these moisture-related issues, providing better long-term performance and compatibility with metal building components.
No. MAXTERRA® installs like other structural panels using standard tools and fasteners. As with any sheathing or underlayment, following the manufacturer’s installation guidelines is essential to ensure performance.
The key difference is confidence. MAXTERRA® is tested, certified, and built to perform as installed.
Yes, MAXTERRA®'s impact resistance and structural certifications make it suitable for high-wind applications. The specific wind load capacities depend on the application and framing system used. For detailed load tables, installation requirements, and ICC-ES evaluation reports, visit our Resource page.