Question:

• Should we use magnesium oxide boards for the installation of partition and screwed-up concealed grid ceiling in permanet wet areas ? 

   

Answer:

• The majority of magnesium oxide boards marketed in Vietnam are manually and semi-manually produced with outdated technology, hence yielding unstable quality products. Obviously, such poor quality magnesium oxide boards are susceptible to high expansion/contraction under continuous up and down movements of temperature and moisture of the surrounding environment. Very often, flush jointed partition and ceiling systems are joint cracked within a short period of time, and in many cases, contractors are unable to hand over their jobs to building investors.
  
  
• In addition, when drywall and ceiling systems are treated with finishing paints and put into operation, within a short time (often not more than 6 months), stains often occur on the surface of walls and ceilings lined with magnesium oxide boards. This phenomenon is called "sweating" by professionals.
  
  
• To avoid these adverse effects, calcium silicate boards / autoclaved cellulose fiber reinforced cement boards are strongly recommended as these lining boards are highly dimensional stable with the fluctuation of moisture and temperature. 6mm thick boards should be used for screwed-up concealed grid ceiling and 9mm thick boards for flush jointed internal partitions in wet areas. For exterior walls lined with calcium silicate boards / autoclaved cellulose fiber reinforced cement boards exposed directly to sun lights and rains, board joints must be filled with acrylic or polyurethane flexible sealants.