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Generally, MGO (Magnesium Oxide) boards perform very well in a wide range of climates, from hot and humid to cold and dry. Their key strengths are moisture resistance and dimensional stability, which makes them highly adaptable. However, their performance can vary depending on the specific formulation, particularly the binder used.

Performance in Humid and Wet Climates ☀️💧

MGO boards are renowned for their resistance to moisture. Unlike wood or gypsum-based products, they do not swell, warp, or delaminate when exposed to water. This makes them ideal for high-humidity environments like bathrooms, kitchens, and basements. Their inorganic composition also means they don’t provide a food source for mold, mildew, or fungus, which is a major advantage in damp conditions.

However, there’s a crucial distinction to be aware of:

• Magnesium Chloride (MgCl₂) based MGO boards can be hygroscopic, meaning they readily absorb moisture from the air, especially in very high humidity. This can lead to a phenomenon known as “weeping” or “crying,” where water droplets containing chloride ions form on the surface. This moisture can cause corrosion of metal fasteners, like screws and nails, which was a significant issue with some early MGO boards, notably in a widely reported case in Denmark.
• Magnesium Sulfate (MgSO₄) based MGO boards are a newer and improved formulation. They are not hygroscopic, so they perform much better in humid conditions and eliminate the risk of metal corrosion. This makes them a more reliable choice for both interior and exterior applications in humid climates.
  

  Performance in Cold and Dry Climates ❄️

  In cold climates, MGO boards excel due to their freeze-thaw resistance. They can withstand repeated cycles of freezing and thawing without losing their structural integrity. This is a significant advantage over other materials that can become brittle and crack in low temperatures.

  Additionally, their excellent thermal insulation properties help to:

  • Reduce heat loss in winter, which contributes to lower heating costs.
  • Prevent thermal bridging, a common issue where heat or cold is transferred through a building’s framing, compromising insulation.