Faster installation
Pneumatic pin installation installs up to 6× faster than traditional cement board.
Request a quoteSTEADFAST™ MGO STRUCTURAL SUBFLOOR
The structural
subfloor built
for steel framing.
Won’t burn. Won’t swell. Won’t rot.
A code-listed magnesium oxide structural subfloor engineered specifically for light-gauge steel framing. Faster to install, built for exposure and designed to perform.
Days weather exposure
Built to withstand open-jobsite moisture without swelling, rotting or delaminating.
Fire-rated assembly
An inorganic MGO core provides dependable fire protection where it matters.
Code listed
ICC-ES ESR-4171 listed and specifically engineered for light-gauge steel framing.
BUILT FOR THE JOBSITE
Engineered to perform.
Built to last.
STEADFAST™ gives builders a smarter alternative to OSB, plywood and cement board. Its inorganic core delivers durability, faster installation and dependable structural performance from installation through occupancy.
- ICC-ES ESR-4171 code listed
- Formaldehyde-free, mold and termite resistant
- Tongue-and-groove edges
- >2,500 psi flexural strength
WHY STEADFAST MGO
Built for every code.
Every climate. Every job.
STEADFAST magnesium-oxide flooring outperforms wood, OSB and cement board across the categories that matter most to builders and code officials.
Fire resistant
Non-combustible MGO core supports a 2-hour fire-rated floor and ceiling assembly.
Moisture proof
Won’t swell, rot or delaminate, with up to 90 days of jobsite weather exposure.
Mold & termite resistant
The inorganic core provides inherent resistance without chemical treatments.
Formaldehyde-free
No formaldehyde, off-gassing or hidden health risks for crews and occupants.
6× faster install
Pneumatic pins mean no screws, no glue and no cure time slowing down the schedule.
Superior acoustics
STC 50+ and IIC 60 tested assemblies for projects with strict acoustic requirements.
Code listed
ICC-ES ESR-4171 listed structural subfloor for light-gauge steel framing.
WHY STEADFAST
Performance that keeps projects moving.
Less weather risk. Faster installation. Fewer callbacks.
PerformanceSTEADFAST MGOTraditional OSB
Fire performance✓ Fire rated× Combustible
Moisture✓ Won’t swell or rot× Swells and delaminates
Mold✓ Mold resistant× Susceptible to mold
Installation✓ Pneumatic pins× Screw installation
Weather exposure✓ Up to 90 days× Immediate protection
IDEAL APPLICATIONS
Made for modern construction.
Multifamily housing
Fire-rated, moisture-proof subflooring built for multi-unit residential projects.
Modular construction
Lightweight, code-listed panels engineered for fast, off-site assembly.
Hospitality
Durable, quiet flooring that holds up to guest-heavy daily use.
Student housing
Impact- and moisture-resistant flooring built for high-density dorm living.
Healthcare
Formaldehyde-free, mold-resistant subflooring for infection-sensitive care environments.
Commercial buildings
Structural performance and fire resistance built for mixed-use commercial spaces.
REAL-WORLD RESULTS
Proven on real projects.
How STEADFAST MGO performs when it matters, on real projects in real conditions.
01CASE STUDY · Wildfire zone
Type III/IV Wildfire-Zone Multi-Family
A coastal California developer needed a non-combustible subfloor where OSB and plywood could not qualify. STEADFAST MGO replaced a slow cement-board workflow while satisfying the required code path.
6× faster installation per floor. Fire-code compliant. Days removed from each phase.
02CASE STUDY · Coastal climate
Modular Build in a Humid Coastal Environment
A modular builder was experiencing OSB swelling, delamination and mold before enclosure. STEADFAST MGO was exposed to rain and coastal humidity without measurable swelling, rot or mold.
Zero moisture-damage rework. Exposure-ready for 90+ days. Mold liability reduced.
03CASE STUDY · Multi-family schedule
10,000 SF Floor Cement Board Replacement
A tight multi-family schedule relied on screw-installed cement board and multiple crew rotations. STEADFAST MGO’s pneumatic-pin system replaced the workflow with no screws, glue or cure time.
Days removed per floor. One fewer crew rotation. The same 2-hour fire rating maintained.PROJECT RESOURCES
Details your team can build from.
Get product specifications, installation information and technical support for your next steel-framed project.
STEADFAST COMPARISON GUIDE
Compare the materials that shape your schedule.
See how STEADFAST MGO compares with traditional OSB and cement board across fire performance, moisture, installation, weather exposure and steel-framing compatibility.
View comparison guide
LET’S BUILD BETTER FLOORS.
Tell us about your project.
Share a few details and our team will help you evaluate fit, specifications, pricing and next steps.
Prefer to talk directly?info@mcflymaterials.com650-374-7419