Attention Mag O board manufacturers: More flexibility needed
Experienced wallboard contractor E. Perry lays out the pros and cons of Magnesium Oxide board
I have years of experience with all North American board and finishing. Mag board is easier to work with then cement board (Durock or similar), but my experience is it is very brittle and cracks easily. As well, fasteners do not countersink easily (similar to cement board). Due to cost and availability the Asian markets have been using Magnesium Oxide board for quite a few years. They have experienced joint cracking issues and so leave a gap between all joints and caulk them. This tells me that in our North American climate, we will experience more issues with the Mag board joints than they have, as our temperature fluctuation is much higher. Mag board is far too brittle as well as not flexible enough to allow for expansion and contraction. The formula for Mag board needs further improvement to hold up and finish the joints in a long standing performance that is satisfactory. I presently work with the product here in Canada, but as an experienced finisher as well as being a carpenter, I see issues with the joints until the material has more flexibility and forgiveness.