What is BMSC 517 New Sulfate MgO Board?

JP Group MagMatrix Brand
Dec 30, 2025
2 min read

BMSC 517 represents the next generation of Magnesium Oxide (MgO) board technology. The "BMSC" stands for Basic Magnesium Sulfate Cementitious, a formulation that specifically utilizes the 5·1·7 phase crystal structure.

Unlike traditional "crying" MgO boards that use magnesium chloride—which can lead to moisture leaching and metal corrosion—the 517 sulfate formula is 100% chloride-free. This makes it the "gold standard" for integration with steel frames, as it eliminates the risk of rusting the very structure it is meant to protect.

Jinpeng Group -- MagMatrix Brand BMSC 517 New Sulfate MGO Board for Fire Rated Wall and Subfloor Structural Sheathing Panel on the steel frame modular constructions applications

Why It’s the Perfect Match for Steel Frame Modular Builds for BMSC 517 New Sulfate MGO Board for Exterior and Subfloor Fire Rated & Structurally Subfloor Sheathing Panel

Modular construction demands materials that are lightweight yet structurally rigid, fire-safe, and durable during transport. BMSC 517 checks every box.

1. Zero Corrosion for Steel Studs

In light-gauge steel (LGS) framing, any salt or chloride in the sheathing can cause rapid oxidation. Because BMSC 517 is sulfate-based, it is chemically stable and non-reactive with steel fasteners and studs.

2. High-Performance Sheathing & Subflooring

Wall Sheathing: Offers superior impact resistance and racking strength compared to gypsum or fiber cement.
Subfloor Sheathing: With a high bending strength (often 22-30 MPa), these boards provide a rock-solid, non-squeak foundation that doesn't warp or swell like plywood or OSB.

3. Ultimate Fire Safety (A1 Rating)

BMSC 517 is classified as A1 Non-Combustible. In a fire event, it releases no toxic smoke and can maintain structural integrity for 1 to 4 hours, providing critical protection for the steel frame, which loses its strength rapidly under high heat.

4. Moisture and Mold Immunity

Modular units are often stored in depots or transported through varying climates. BMSC 517’s low solubility (0.034g/100g water) ensures it won't delaminate, rot, or grow mold even if exposed to high humidity or rain during the assembly phase.

Jinpeng Group -- MagMatrix Brand BMSC 517 New Sulfate MGO Board for Fire Rated Wall and Subfloor Structural Sheathing Panel on the steel frame modular constructions applications

Performance Comparison: BMSC 517 vs. Traditional Materials

Feature	BMSC 517 (Sulfate MgO)	Traditional MgO (Chloride)	Plywood / OSB	Gypsum (Drywall)
Corrosion Risk	Zero	High (Leaching)	Low	Low
Fire Rating	Class A1	Class A1	Combustible	Class A
Moisture Effect	Stable	Swells/Leaches	Warps/Rots	Degrades
Impact Strength	Very High	High	Medium	Low
Eco-Impact	Carbon Neutral	Low	Medium	High Energy

Strategic Advantages for Modular Manufacturers

Precision and Speed: The boards can be "scored and snapped" or cut with standard power saws, reducing fabrication time in the factory.
Reduced Weight: It provides higher strength-to-weight ratios than fiber cement, reducing the overall weight of the module and lowering shipping costs.
Healthier Interiors: Free of formaldehyde, asbestos, and silica, it contributes to excellent Indoor Air Quality (IAQ)—a key selling point for modern residential modules.

Conclusion

The transition to BMSC 517 New Sulfate MgO Board is more than a material upgrade; it’s a structural insurance policy for modular builders. By combining the fire-rated power of minerals with a chemistry that respects steel, it ensures that the "homes of the future" are safe, dry, and built to last.