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MAXTERRA® MgO Panels deliver non-combustible exterior sheathing, fire-rated interior wall board, and a complete floor system that eliminates wet-laid gypsum. ICC-ES evaluated, UL fire-rated, and proven in the field.

Why Wet-laid Gypsum Keeps Costing You More

Multifamily developers and GCs are caught between IBC Type III code requirements and a wet-trade floor system that fights your schedule at every turn.

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5–7 day cure cycle per floor. Wet-laid gypsum locks in waiting time at every level, compressing your ability to sequence trades efficiently. 

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Moisture damage and callbacks. Wet-laid gypsum introduces bulk water during construction, a leading cause of mold, delaminated flooring, and post-occupancy warranty claims. 

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Subcontractor mobilization risk.  Wet-laid gypsum requires a specialty sub. Scheduling conflicts, material shortages, or quality disputes can halt your entire project. 

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MOC chemistry. Commodity MgO boards commonly use magnesium oxychloride (MOC), which corrodes fasteners and framing members. They fail ICC-ES testing protocols.

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FRTW compliance ambiguity. Fire-retardant-treated wood is a combustible material treated after the fact, not inherently noncombustible, despite common field assumptions. 

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Advantage

Our MOS (magnesium oxysulfate) chemistry delivers what your project schedule, code inspector, and ownership group all need from a single product system.

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Dry Installation.  No water introduced to the building envelope, ever. Full floor system installs with standard fasteners in one trade sequence.

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Inherently Non-combustible. ASTM E136 classified, not a treated combustible material. Qualifies for Type III exterior wall applications as referenced by the IBC.

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ICC-ES evaluated. ESR-5193 (sheathing), ESR-5192 (underlayment), ESR-5194 (structural floor panel), ESR-5506 (MagRock® Premium Wall board). Documentation ready for plan review and field inspection. 

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MOS chemistry. Doesn't absorb moisture or leach chloride salts. Corrosion of framing and fasteners is not a concern, confirmed by long-term durability testing.

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UL H524, 2-hour rated. Full assembly rating achieved with fewer layers than competing products. Simplifies procurement and inspection while saving money.

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EXTERIOR WALLS AIA Mockup 2401 1

Structural Wall Sheathing

Replaces OSB or plywood sheathing on exterior wall framing. Noncombustible per ASTM E136, qualifying forType III exterior wall applications as referenced by the IBC. No FRTW substitution arguments. Available in 1/2" and 5/8" for CFS and wood-frame applications.

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    Thickness 1/2" & 5/8" - CFS & wood framing

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    ASTM E136 Noncombustible - MOS chemistry

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    ICC-ES ESR-5193

Product Details →
FLOOR UNDERLAYMENT AIA Mockup 2401 1 (1)

Fire- and Water-Resistant Underlayment 

 1/2" MAXTERRA® underlayment installs over existing OSB subfloor, set by your framing sub in the same pass. Eliminates wet-laid gypsum subcontractor, 5-7 day cure time, moisture risk, and flooring adhesion failures in one product swap. 

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    Thickness 1/2" - installs over existing OSB

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    No cure time - dry install, no wet trade

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    ICC-ES ESR-5192

Product Details →
STRUCTURAL FLOOR AIA Mockup 2401 2

Single Layer Structural Floor Panel

 3/4" MAXTERRA® Structural Floor Panel replaces both OSB subfloor and wet-laid gypsum in a single layer. Maximum schedule compression, zero wet trade, zero separate topping layer. 

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    Thickness 3/4" - span rating 24" OC

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    Load capacity 133 psf at L/480 deflection

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    ASTM E136 Non-Combustible MOS chemistry

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    ICC-ES ESR-5194 - UL H524 2-hour rated

Product Details →
INTERIOR WALLS AIA Mockup 2401 1 (2)

MagRock® Premium Wall Board 

Interior wall panel replacing standard gypsum panel products. ASTM E84 Class A rated. ASTM G21 mold resistance - 0 growth observed. MOS chemistry, no moisture absorption or chloride leaching. 

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    Thickness 3/8", 1/2", 5/8"

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    ASTM E84 Flame Spread 0, Smoke 5 - Class A

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    ICC-ES ESR-5506 replaces interior gypsum

Product Details →

It's Not the Cost of the Board.
It's the Cost of the Build.

When you need a 2-hour fire-rated floor assembly... more layers, heavier steel,
and specialty material requirements add up to more cost. 

Assembly
Feature		 MAXTERRA®(H524) Competitor 1(H515) Competitor 2(G575) Competitor 3(H509) Competitor 4(H514)
Ceiling
Gypsum		 1 layer, Type ULIX 1–2 layers, Type ULIX 2 layers, Type FSW-C (specialty) 2 layers, Type FSW-C (specialty) 1 layer, Type C (National Gypsum only)
Additional Floor Topping None Varies by assembly None None None
Sound Mat in Assembly None Specified in some None None None
Truss Steel Gauge 20 ga 20 ga 16 ga 16 ga 16 ga
Insulation Any qualifying batt Any qualifying batt Any qualifying batt Any qualifying batt R-13, 0.92 density (restricted)
Blocking Required None (tongue & groove) None Required Required None

Data sourced from UL fire-resistance design assemblies (H524, H515, G575, H509, H514).

Proven on Real Projects

MAXTERRA® has been specified and installed on
Multifamily Projects across the country.

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CLEBURNE, TEXAS

 Alps Cleburne Apartments

Project Type

Class A Garden-Style Multifamily

Product

MAXTERRA® Single Layer Structural Floor Panels

Framing Type

Wood-Framed Construction

Location

Cleburne, Texas

Units

266

DJI_20250529140928_0053_D
PLANT CITY, FLORIDA

 The Henry Apartments 

Project Type

Multifamily Residential

Product

MAXTERRA® Single Layer Structural Floor Panels

Framing Type

Cold-Formed Steel (CFS) Framing

Location

Plant City, Florida

Units

96

DJI_20250529140928_0053_D (1)
DOVER, DELAWARE

 Metro Properties Multifamily 

Project Type

Multifamily

Product

1/2” MAXTERRA® Flooring Underlayment

Framing Type

Wood-Framed Construction

Location

Dover, Delaware

Application

Underlayment over OSB Subfloor

"The biggest benefit we found was that we saved 2-3 weeks on our construction schedule by using this product."

Megan Leatherwood,
Construction Superintendent at Trafalgar Homes

View All Project Spotlights →
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Frame 781
CODE & COMPLIANCE

Get Spec'd. Get Approved.

The most highly certified MgO product on the market. Every claim backed
by ICC-ES evaluation reports and UL assembly listings, not marketing claims.

ICC-ES ESR-5193

Exterior Sheathing, Type III Compliance

Covers MAXTERRA® MgO sheathing for exterior wall applications on CFS and wood-frame construction. Noncombustible per ASTM E136, qualifying for Type III exterior wall applications as referenced by the IBC. This is the report that ends the FRTW conversation before it starts.

ICC-ES ESR-5192

Floor Underlayment, Fire-and-Water-Resistant 

Covers MAXTERRA® 1/2" underlayment installed over OSB subfloor as a wet-laid gypsum replacement. Addresses fire performance, structural contribution, and moisture resistance. Provides the documentation path for permit submission on floor-ceiling assemblies. 

ICC-ES ESR-5194

Structural Floor Panel, Single Layer System 

Covers MAXTERRA® 3/4" single-layer structural floor panel as a combined replacement for OSB subfloor and wet-laid gypsum. Span rating, load tables, and deflection criteria included, everything your structural engineer needs for the floor framing plan. .

UL H524

2-Hour Fire-Rated Floor-Ceiling Assembly 

Full UL-listed 2-hour fire-rated assembly for CFS truss construction with MAXTERRA® floor panel and single layer of ceiling gypsum. Fewer components than competing H-series assemblies, simpler procurement, simpler inspection, same rating. 

ICC-ES ESR-5506

MagRock® Premium Wall Board - Interior Fire Resistance 

Covers MagRock® MgO wall board for interior wall applications as a replacement for traditional gypsum panels. ASTM E84 Flame Spread Index of 0, Smoke Developed Index of 5. Zero mold growth per ASTM G21. The documentation path for interior fire-resistant wall assemblies without gypsum. 

EPD VERIFIED

Environmental Product Declaration 

The only MgO panel with a verified Environmental Product Declaration (EPD) for the North American market. Contributes to LEED v4 credit pathways including MR Credit: Building Product Disclosure and Environmental Product Declarations. VOC-free, quartz silica-free, and manufactured through a low-carbon mineral-based process. 

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Frequently Asked
Questions

Is MAXTERRA® truly noncombustible for Type III exterior walls, or is it just “fire-rated”?

Noncombustible, not just fire-rated. MAXTERRA® MgO panels are classified as noncombustible per ASTM E136 testing, qualifying for Type III exterior wall applications as referenced by the IBC. Fire-retardant-treated wood (FRTW) is a combustible material treated to reduce flame spread, it is not classified as noncombustible. MAXTERRA®’s ICC-ES ESR-5193 report is the documentation building officials need to confirm compliance without case-by-case interpretation.

 Learn how to mitigate the 9 most common multifamily construction risks → 

Can MAXTERRA® replace wet-laid gypsum in an existing project mid-schedule?

Yes, with one of two paths depending on where you are in the framing sequence. If OSB subfloor is already installed, MAXTERRA® 1/2" underlayment (ESR-5192) goes over it and eliminates the wet-laid gypsum pour. If you’re at pre-subfloor stage, the 3/4" structural floor panel (ESR-5194) replaces both OSB and wet-laid gypsum in a single layer. In both cases, your framing subcontractor can install the panels, no new sub required. Contact your NEXGEN local rep for a project-specific installation sequence.

See how MAXTERRA® compares to gypsum underlayment →

What is the MOS vs. MOC chemistry difference and why does it matter?

MAXTERRA® uses magnesium oxysulfate (MOS) chemistry. Many commodity MgO panels use magnesium oxychloride (MOC). MOC panels absorb atmospheric moisture over time, leach chloride salts, and corrode embedded fasteners and metal framing. This can lead to structural degradation that doesn’t manifest until post-occupancy. MOS-based panels like MAXTERRA® do not exhibit these behaviors. MAXTERRA® holds the most extensive portfolio of third-party testing and certifications of any MgO product on the market, including three ICC-ES evaluation reports and a UL-listed 2-hour fire-rated assembly.

Understand multifamily floor and wall assembly challenges →

Does MAXTERRA® cost more than wet-laid gypsum? How do I make the economic case?

When compared on an installed-cost basis, the MAXTERRA® underlayment path (OSB subfloor + 1/2" MAXTERRA® underlayment) typically costs less per square foot than the traditional assembly (OSB subfloor + wet-laid gypsum underlayment + sound mat). MAXTERRA® eliminates pour scheduling, cure time, and moisture-related callbacks, which further reduces total project cost. Contact your NEXGEN local rep for a project-specific cost comparison.

Read why one builder replaced wet-laid gypsum with MAXTERRA® →

Which framing systems is MAXTERRA® compatible with?

MAXTERRA® is the only MgO product with ICC-ES certification for both cold-formed steel (CFS) and wood-frame construction. The structural wall sheathing (ESR-5193) is evaluated for CFS and wood framing. The structural floor panel (ESR-5194) is evaluated for both CFS and wood joist systems. The fire-and-water-resistant underlayment (ESR-5192) is evaluated for CFS truss systems, which is the dominant framing system in Type III multifamily. If your project uses a hybrid framing system or non-standard truss layout, contact your NEXGEN representative. The ICC-ES reports include span tables and load data that your structural engineer can reference for project-specific conditions.

Learn about MAXTERRA®’s dual CFS and wood-frame certification →

Build Faster. Build Safer.
Build Smarter.

From exterior sheathing to floor systems to interior wall board, get the documentation and support your project needs.  

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