What Is MgO Board?

 

Magnesium oxide board “MgO board” is a factory-made, non-insulating sheathing board product. It can be used for a number of applications including wall and ceiling linings, fascias, soffits, tile backing and underlayments. It is made of magnesium oxide, a type of mineral cement, and is commonly called simply “MgO” (pronounced emm-gee-oh) due to its chemical composition of magnesium (chemical symbol Mg) and oxygen (chemical symbol O). Think of MgO as a type of sheathing board–sort of like drywall or cement board–but with much-improved characteristics such as fire resistance, weatherability, strength, resistance to mold and mildew, and so on.

 

MgO is available in many forms, and for building construction comes in various thicknesses and sheet sizes. It also comes in various grades, such as smooth finishes, rough textures, and utility grades. It is white, beige or light gray in color, and has a “hard” sound when rapped with your knuckles–somewhat like portland cement board. There are dozens of companies that make MgO board, most of which are in Asia. There are several large producers, but most are small local manufacturers who serve a region.

 

Not much MgO is used in North America so far, but no doubt will become much more widely used in the future.

What’s it made of?

Pure magnesium is a silvery metal element (it is shown in the chemistry Periodic Table) and is a solid at room temperature (unlike mercury, also a metal, which is liquid at room temperature). Magnesium is somewhat like aluminum, but lighter. The so-called “mag wheels” on sports cars in the ‘60s and ‘70s were actually mostly made of aluminum, but also had some magnesium in them. Like aluminum, magnesium is usually used in alloy form, particularly for lightweight high performance structures like airplanes and race cars.

 

Pure magnesium, in raw form, is not stable–it burns–they make flares and fireworks from it. MgO, however, is the exact opposite. It is completely nonflammable and used for fireproofing and as furnace liners.

 

Oxygen, when combined with magnesium under heat and pressure can produce a stone-like material: MgO. MgO exists in gigantic deposits as raw “rock” and is mined like other minerals. It is ground up into a powder, which is then combined with water to make a cement-like (adhesive) material. About 70 percent of the world’s MgO is in Asia. Other deposits are located elsewhere around the globe, but not all have the correct quality for making sheathing. There is sufficient mine-able MgO spread around the world to make enough “MgO drywall” for centuries. MgO board also contains other magnesium-based components, but MgO is the main one.