05 Sep Are Magnesium Oxide Boards Water-resistant?
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Are you looking for a water-resistant construction material? Well, look no further! In this post, I will explain everything you need to know about MgO boards and their water resistance!
MgO Boards and Water: A Perfect Match or a Mishap?
MgO boards are water—and moisture-resistant, as well as mold—and mildew-resistant. However, keep in mind that water resistance does not mean waterproof.
MgO’s Water Resistance
As mentioned, magnesium oxide boards are highly water resistant. This feature makes them an excellent choice for areas exposed to moisture! Unlike traditional gypsum boards, MgO boards do not swell or warp. Most importantly, they do not degrade when in contact with water. Because of their water resistance, MgO boards can maintain their structural integrity. MgO boards’ low water absorption makes them ideal for use in bathrooms, kitchens, and humid environments. Generally, if your issue is moisture or water exposure, your solution is MgO boards!
MgO’s Mold Resistance
MgO boards also offer exceptional resistance to mold. The reason lies in their specific inorganic composition with water-resistant properties. Unlike organic materials, MgO boards do not provide a food source for mold spores. You have probably seen the effect of water and moisture on plywood! It is not pretty! Because of their inorganic composition, they are suitable for use in damp or humid areas. The bathroom and kitchen are not the only areas prone to moisture and mold. Basements are also “victims of mold”, so MgO boards are ideal for constructing basements. Their mold resistance also helps with indoor air quality. Ultimately, this feature contributes to longevity and the health of the building structure!
MgO’s Mildew Resistance
Mildew resistance is another key advantage of MgO boards. These boards are designed to withstand the conditions that typically promote mildew growth. The water-resistant nature of MgO boards ensures that they do not retain moisture. As a result, this reduces the risk of mildew development. The MgO boards’ resistance to mildew, mold, and water primarily comes from magnesium oxide.
Another important point is the absence of hygroscopic components. MgO boards are made of magnesium oxide, fillers like perlite and vermiculite, and binders. Sometimes, binders used for MgO boards can be hygroscopic. It means that the boards readily absorb moisture from the air.
Water Resistance of Standard MgO Boards
There are different types of MgO boards! Even though you may think that all MgO boards are the same—no, they are not! The key difference is their formulation, which affects their performance and water resistance. Let’s check it out!
MgO boards with Magnesium Chloride
MgO boards with magnesium chloride have initial water resistance. Magnesium chloride helps to form a dense, strong matrix when combined with magnesium oxide. This “concoction” provides robust structural integrity. But, magnesium chloride comes with some disadvantages. It is highly hygroscopic, and it absorbs moisture from the environment. If you are living in a humid area, this can be an issue. Why? A common problem with MgO boards with chloride is efflorescence. That refers to powdery deposits on MgO boards due to low moisture resistance. So, if the MgO boards absorb and retain moisture, this will result in a loss of structural integrity. Although MgO boards do not swell or warp, it can happen with boards made with chloride. Plus, their long-term performance can be compromised.
MgO Boards with Magnesium Sulfate
MgO boards with magnesium sulfate offer much better water resistance. These boards are designed to overcome the moisture-related issues associated with magnesium chloride. First, magnesium sulfate is not hygroscopic. As it does not retain moisture, it enhances the long-term water resistance. Although it may seem unrelated, their water-resistant features affect their other properties. You cannot expect the boards to be stable and durable if they are warping and swelling! The only downside with these boards is their price! They can be expensive because of the high-quality raw materials and binders. Sulfate offers better properties and, hence, is more expensive than chloride!
Term “Crying Boards”: What Does it Mean?
Another common problem of MgO boards with magnesium chloride is “crying boards.” Because of their water absorption, they start condensing the moisture on the surface as visible water droplets. They are very similar to tears, which explains the term. These crying boards are good grounds for mold growth and corrosion. The chloride content in the water droplet can cause corrosion of metal components. The water droplets cause staining on the boards. This will compromise the finished look of the wall or ceiling. Unlike these boards, the ones with sulfate do not experience problems like “crying boards.”
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Comparing Water Resistance: MgO boards vs. Gypsum vs. Plywood vs. Cement Board
MgO Boards, plywood, and gypsum boards are all common building materials. But they have distinct properties and applications. When it comes to water resistance, these materials perform quite differently.
MgO vs. Plywood
Plywood is an engineered wood product made from thin layers of wood veneer glued together. Construction professionals use it in construction for its strength and versatility. Standard plywood has limited water resistance. Prolonged exposure to moisture will cause it to swell, warp, and delaminate. As it is made of organic materials, it is susceptible to mold growth. However, they can be treated for improved water resistance. But this asks for extra treatment. Plus, if exposed to moisture or dampness, plywood will deteriorate over time, causing the structure to lose stability.
MgO vs. Gypsum Board
Standard drywall or gypsum wall is made from a core of gypsum plaster. It is commonly used for exterior walls and ceilings. Unlike MgO boards, drywall has poor water resistance. It absorbs moisture, resulting in swelling and warping. Like plywood, drywall can be treated with water-resistant additives. But it should never be exposed to direct water. Again, treated drywall has some water resistance but is not waterproof. Even treated, drywall is still prone to issues over time. Most professionals do not suggest using gypsum in areas with regular dampness.
MgO vs. Cement Board
Cement boards are composed of cement and reinforcing fibers. Construction professionals use them as backing boards for tiles and exterior applications. Both MgO boards and cement boards offer excellent water resistance. Cement boards are also highly resistant to moisture and do not swell or degrade when exposed to water.
But, installing cement boards is a hassle compared to MgO boards. MgO boards are lighter and, hence, easier to handle and install.
Conclusion
MgO boards offer premium water, mold, mildew, and moisture resistance. Yet, this does not mean they are waterproof. The MgO’s unique formulations and composition affect their water resistance. The MgO boards with magnesium sulfate offer better resistance to moisture than those with chloride. I’ve also explained what “crying boards” refer to and the cause of their “crying.” Lastly, I’ve presented a comparison of water-resistant MgOs with other traditional materials.