Question:

• How long, expressed in minutes, can 12.7mm or 15.9mm or 25.4mm thick fire rated wallboard of X, Y, Z manufacturer resist to the attack of fire ?

   

Answer:

• "Fire reaction of building materials" or "fire reaction", and "fire resistance of building systems" or "fire resistance", are two distinctive, separate features related to fire in the construction and building industry.

   

• When tested under American standard ASTM E84 or Australian standard AS 1530-part 3, wallboards, a specific type of gypsum boards that have special paper liner at the front and back faces, are classified as “limited combustible building products". Meanwhile, fibrous cast gypsum boards (paperless gypsum boards that are reinforced with fibers in their gypsum core) are identified as “non-combustible building products”.

   

• Let's consider an interior or exterior gypsum drywall partition or ceiling system constructed from timber or steel frame, lined with gypsum boards or magnesium oxide boards or calcium silicate boards or auctoclaved cellulose fiber reinforced cement boards, fastened with appropriate nails or screws, flushed jointed with reinforced tapes and jointing compounds, and finally caulked with fire rated sealants. This system is deemed to have “a certain fire resistance level” when successfully passes the fire test under strictly controlled laboratory conditions as specified under American standard ASTM E119 or British standard BS 476 - part 21 & 22 or European standard EN 1364 - part 1 & 2 or Australian standard AS 1530 - part 4. Its fire resitance level or fire rating level can be 30 minutes / 60 minutes / 90 minutes / 120 minutes / 180 minutes / 240 minutes.

   

• In short, all over the world, nobody rates the fire resistance level of a particular material or single product (for instance, gypsum wallboard, magnesium oxide board, calcium silicate board, autoclaved cellulose fiber reinforced cement board). Instead, we only test and classify the fire resistance level of a specific system consisting of different components (say a floor/ceiling or roof/ceiling or drywall partition system lined with fire rated gypsum wallboards). Thus, a question like "How long, expressed in minutes, can 12.7mm or 15.9mm or 25.4mm thick fire rated wallboard of X, Y, Z manufacturer resist to the attack of fire ?" is obviously meaningless.