Product Comparison

See how our Magnesium Oxide Board compares to other materials/boards.

Extremegreen Cement Board Gypsum Wallboard Gypsum Sheathing Plywood OSB
Fire Resistant Yes No Minimal Minimal No No
Flame Spread 0 0 Low / 15 Low / 10 High High
Smoke Developed 0 0 Low Low High High
Combustibility Non-combustible Non-combustible Paper Facing Paper Facing Highly Flammable Highly Flammable
Water Resistant Yes * No No No No No
Mould Resistant Yes Yes No No No No
Termite Resistant Yes Yes Yes Yes No No
Vapour Permeable Yes No No No Negligable Slight
Impact Strength Very High Medium Low Low High Medium
Structural Yes No No No Yes Yes
Weight (lbs/sq.ft) 2.5 2.9 1.9 2.4 1.6 2.0
Freeze/Thaw Excellent Good Poor Poor Good Good
Carbon Footprint Very low High ** High ** High ** Low *** Moderate


* Whether magnesium oxide board is actually water resistant or not is entirely formula and manufacturer dependent. Most magnesium oxide manufactured materials are not water resistant despite the manufacturers’ claims to the contrary.

** Cement board and gypsum board manufacturers may/do claim that their manufacturing operation(s) have a low to moderate carbon footprint, however, this is only achievable if significant quantities of fly ash are recycled and used as fillers in their board(s). Fly ash is usually toxic, or contains some degree of toxicity. The presence of fly ash in any building material cannot be advantageous to human health. In conclusion an increase in fly ash in turn increases the negative health effects to people.

*** Plywood and O.S.B. manufacturers should only claim to have a low – moderate carbon footprint if the wood used to manufacture their product(s) is harvested from a sustainable re-forestation programme. Even so, it remains debatable that replacing a naturally slow growing tree with a fast growing softwood tree is an ecologically sound practice.