That is a very specific product configuration: Magnesium Oxide (MGO) Board Tongue & Groove (T&G) Exterior Horizontal Siding.
This product combines the core benefits of MGO board with a popular siding installation profile.
Product Description and Purpose
- The Core Material: MGO Board
MGO board is a mineral-based cementitious building material composed mainly of Magnesium Oxide (MgO) and Magnesium Sulfate ($\text{MgSO}_4$).
- Key Benefits:
- Non-Combustible (Class A/A1 Fire-Rated): Provides superior fire safety.
- Water & Moisture Resistant: Does not swell, warp, or delaminate when exposed to moisture (unlike wood or gypsum).
- High Strength: Offers excellent impact and flexural strength.
- Mold/Mildew Resistance: Due to its inorganic nature.
- Health Safe: Typically free from VOCs, formaldehyde, and asbestos.
- The Profile: Tongue & Groove (T&G) or Shiplap
The T&G or Shiplap edge profile is engineered for exterior cladding for several functional reasons:
- Hidden Fasteners: The fasteners (screws or nails) are driven through the ‘tongue’ or ‘rabbet’ and concealed by the next board’s ‘groove’ or overlap, resulting in a clean, face-fastener-free aesthetic.
- Easy Alignment: The interlocking edges ensure quick, straight, and precise horizontal alignment during installation.
- Weather Protection: The overlapping or interlocking joint helps to shed water away from the wall assembly and prevents wind-driven rain from penetrating the air barrier directly behind the siding.
- Horizontal Siding: Refers to the way the boards are oriented on the wall (parallel to the ground), creating the familiar appearance of traditional clapboard or plank siding
Exterior Application Notes
When MGO board is specifically used as an exterior cladding or siding, it is critical to distinguish between its use as a Structural Sheathing and an Finished Siding Product.
- MGO T&G as Structural Sheathing (Most Common Use)
In this context, the MGO board is used underneath the final cladding (like stucco, brick, or wood siding).
- Purpose: To provide a non-combustible, moisture-resistant layer that adds structural support and acts as the fire-rated substrate for the entire wall assembly.
- Profile: The T&G or Shiplap edges allow the sheets (often $4′ \times 8’$ or $4′ \times 10’$) to lock together, providing a better shear wall connection than standard square-edge panels.
MGO T&G as Finished Siding (Aesthetic Cladding)
- Purpose: The MGO board is the visible, final finish of the exterior wall.
- Profile: Typically sold as narrow planks (e.g., 6-inch or 8-inch wide) with a T&G or Nickel Gap profile.
- Finish: For this application, the product must have a specialized, high-performance exterior coating (paint, texture, or wood-grain finish) applied by the manufacturer or the installer to protect the MGO matrix from long-term UV exposure and freeze-thaw cycles.
NOV
2025