Updated June 8, 2026
MAXTERRA® MgO (magnesium oxide) board is used across the building envelope and interior: non-combustible structural wall sheathing and structural floor panels, plus fire-resistant tile backer, underlayment, and interior wall board. The same system shows up in multifamily, senior living, data center, hotel, healthcare, and modular construction, and it can be specified across IBC Type I through Type V construction. In short, one MgO board family does the work of several, from the sheathing out to the floors underfoot.
Below is where it fits, organized by the part of the building you are working on and the building types it serves.
As structural wall sheathing, MAXTERRA® replaces plywood, OSB, or paper-faced gypsum sheathing on exterior walls. It is non-combustible (ASTM E136), so it adds no fuel load to the wall assembly, which is what makes it a fit for the non-combustible exterior walls Type III construction requires. With no paper facing and no organic food source, it resists the moisture and mold that degrade paper-faced and wood sheathing, holds up to jobsite exposure through the dry-in, and brings added storm resistance to the finished wall.
The structural floor panel is a single-ply, non-combustible, structural subfloor used on floors and roofs. It carries the load and delivers rated fire and sound performance in tested assemblies like UL H531, which lets it replace a poured subfloor-and-gypcrete assembly in many builds. That removes a wet trade from the critical path: no water, no shoring, no cure time. You can model that schedule and cost difference with the Skip-the-Gyp calculator.
Wet areas expose the weakness of paper-faced board fast. Installed over an OSB or wood subfloor, MAXTERRA’s water-resistant underlayment and tile backer give tile and stone a fire-resistant, mold-resistant substrate that holds up in bathrooms, kitchens, and laundry rooms where paper-faced board fails. It is also the second way MAXTERRA can take the place of poured gypsum underlayment: lay it dry, directly over the subfloor.
For interior partitions, MagRock® wall board is a fire-resistant, abuse- and impact-resistant alternative to standard drywall. It holds up in high-traffic corridors, stairwells, and amenity spaces, and it resists the mold and moisture that compromise paper-faced gypsum board over time.
It is worth being precise, because the distinction matters to specifiers and code officials. MAXTERRA’s structural wall and floor panels are non-combustible per ASTM E136. Used in properly designed assemblies, they help teams meet the non-combustible material requirements for the building elements they form. The MagRock® wall board, underlayment, and backer board are fire-resistant rather than non-combustible. The non-combustible structural panels are also used in UL fire-rated assemblies, including the UL H531 2-hour floor-ceiling assembly.
The same board family adapts to very different projects. See how it specs into each on the Building Types hub:
Not sure which IBC construction type your project is governed by? Our series on Type I through Type V construction explains where MgO panels fit in each.
From the exterior sheathing to the floors and the wet-area tile, MAXTERRA® MgO board does the work of several different products with one non-combustible structural core and a fire-resistant finish family around it. See how it fits your project on the Building Types hub, or request a sample and put it in your own hands.
Yes. As structural wall sheathing, MAXTERRA® is built for the exterior envelope. It is non-combustible, and it resists moisture and mold during jobsite exposure and dry-in, with no paper facing to break down.
Yes. MAXTERRA® underlayment and backer board are water-resistant and mold-resistant, which makes them a stable substrate for tile and stone in bathrooms, kitchens, and other high-humidity spaces where paper-faced board fails.
Yes, in two ways. The single-layer structural floor panel can replace the subfloor-and-gypcrete assembly outright, or MAXTERRA® underlayment can be installed dry over an existing OSB subfloor in place of poured gypsum. Both install with no special tools and no specialty crews.
Yes. They describe the same product. “Board” is the common term in the field and in replacement-material conversations, while “panel” is the technical and specification term. MAXTERRA® uses both.
The structural floor and wall panels are non-combustible per ASTM E136. The MagRock wall board, underlayment, and backer board are fire-resistant rather than non-combustible. Non-combustibility is evaluated by material and assembly, not by brand alone, so match the right MAXTERRA® panel to the required assembly.