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The concept of “MGO Flexible Sheathing Sheet” refers to the thinner, lower-density versions of Magnesium Oxide (MGO) board that exhibit a surprising degree of flexibility compared to traditional, rigid building materials like thicker cement board or plywood.

While MGO board is an inherently cementitious and durable material, manufacturers engineer specific products to be flexible enough for certain applications.

Key Characteristics of Flexible MGO Sheathing

The “flexibility” of MGO sheathing is a relative term. It is achieved through:

1. Reduced Thickness: The flexibility is directly tied to the panel’s thickness. MGO sheets in the 3 mm (1/8″) to 6 mm (1/4″) range are considered flexible, allowing them to bend significantly without breaking.
2. Lower Density: These thinner, more flexible sheets often have a slightly lower density compared to the high-density structural floor panels, contributing to their improved workability.
3. Fiberglass Reinforcement: Like all quality MGO products, these sheets contain multiple layers of high-tensile fiberglass mesh. The mesh is what allows the sheet to bend without fracturing the mineral core, much like rebar in concrete.

Primary Applications

The main purpose of flexible MGO sheathing is to conform to curved or non-planar surfaces, particularly in situations where high fire-resistance is required.

• Curved Walls and Ceilings: The most common use is creating curved architectural features in highly fire-rated environments, such as lobby accents, curved partitions, or dome ceilings.
• Mobile and Modular Construction: The light weight and flexibility make the thinner sheets easy to handle and ideal for use in mobile homes, RVs, and modular structures where minimizing weight is crucial.
• Surface Backing/Underlayment: The thin sheets are often used as a fire-rated substrate for finishes like veneer, decorative laminates, or wallpaper, especially when non-combustibility is a requirement for the assembly.
• Tile Backer: Thin MGO sheets (e.g., ²1/4”or 6 mm) are popular as tile backer board in wet areas due to their excellent moisture and mold resistance.³

Bending Radius (Approximate)

The actual bending radius depends heavily on the specific manufacturer, density, and thickness. For thin, utility-grade MGO sheets 3 mm or 6 mm, the bending capacity can be quite impressive:

• 3 mm (1/8″): Can often be bent to a radius as tight as 1 foot (300 mm) or less for gentle curves.
• 6 mm (1/4″): Can typically be bent to a radius of approximately 2 feet (600 mm) or more

Important Note on Flexibility and Structural Integrity:

It is crucial to understand that MGO’s flexibility is generally inversely proportional to its structural rating. The thin, flexible sheets are not typically used as load-bearing or structural sheathing (which requires 1/2” or thicker panels) but rather as a non-structural fire- and moisture-resistant skin