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Can Canadian Homeowners Trust in Magnesium Oxide Boards?

What if the material that made up your home’s walls could keep your family safer and healthier than traditional building materials? Magnesium Oxide Board (MgO board) is an innovative building product, new to the Canadian marketplace, that many builders and architects believe can do exactly that.

However for every one person who loves this innovative building product, there is another vehemently opposed to it. Let’s take a closer look at the good and bad sides of magnesium board.

What is Magnesium Board?

MgO boards are comprised of Magnesium oxide, which has been introduced into a cement mixture and cast into thin panels. These panels are then specially cured to make them useable in residential building projects. The result is a strong alternative sheathing material with antimicrobial properties that can be used over wood and metal framed houses. It is used for walls, ceilings, subfloors, and other building applications, where gypsum, plywood, or cement might traditionally be found.

The Benefits of MgO Board


While magnesium board is absorbent, it will not degrade when exposed to water.

Impervious to Fire

MgO Board is a certified fire resistant building material. In fact, numerous tests have been done comparing the fire-resistance of magnesium board to plywood and traditional drywall, with MgO coming out the victor.

It is worth noting that there is one caveat, as mentioned in an article by alternative builder Ben Polly, in Canadian Contractor magazine.

“Beware of fire rating claims. (In Ontario at least) Unless the manufacturer has acquired a BMEC number (or possibly a ULC or CSA approval) for their product it falls outside Part 3 or 9 of the Code; thus an engineer must sign off if it is to be counted toward total fire separation calculations.” (Canadian

Insect/Termite Resistant

MgO contains no ingredients that are edible by insects like termites or ants. This causes them to be disinterested and seek substance elsewhere.

Mold/Mildew Proof

Magnesium Board is antimicrobial. This means that it does not support the growth of mold or mildew.

Impact Resistant

The impact resistance was tested by experts in Miami Dade County, Florida, as a building material strong enough to resist hurricanes.

Some Additional Benefits of MgO Board

  • Easy to paint
  • Won’t need replacing in the event of a flood
  • No digs or gouges to the drywall
  • No off-gassing of VOCs

Reported Issues

While many reviews of MgO board have been glowing, both from builders and homeowners/business owners alike, this new building material isn’t without its issues.


One of the main issues with this product is that these boards are almost exclusively manufactured in China. This origin tends to conjure memories of the toxic Chinese drywall crisis that occurred between 2004 and 2007 in North America.  While MgO contains no VOCs, carcinogens, or toxins, it is only natural for some builders and homeowners to be wary.


In 2014, Ingeniøren –the official magazine of the Engineering Association of Denmark began reporting widespread damage to buildings constructed with MgO plates.  Surprisingly, moisture appears to be at the heart of this damage.

“Some experts say that the boards should have been sealed in order to prevent water penetrating the boards. Others point to quality problems. Interestingly, this appears to have been a Danish phenomenon for now. Could it be due to the climate? Is the issue bound to affect buildings in other countries? While the extent of the damage in Denmark becomes more apparent, we’ll be watching to see whether this problem affects markets elsewhere.” (

Take Time to Research

Before you decide to make any new product a part of your home renovation, take time to do extensive research. Learn everything you can, both the good and the bad, and always make sure that you’re working with a reputable renovation professional.

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