An MFT ceiling

[woodferret]

It literally specifies flame spread rating 0-25 under ASTM E84.  There's no vagueness on what the test conditions and applicability are.

 

[Packard]

It literally specifies flame spread rating 0-25 under ASTM E84.  There's no vagueness on what the test conditions and applicability are.

My only point was that “fire rated” might mean something other than what we have in our minds. 

I just read the standard. I do not fully understand the limitations that they are placing on this test.

Specifically, it says it applies to fiber cement board over red oak.  And in the horizontal (ceiling) position.

Of course for these ceiling panels, that is appropriate.  If there were a wall panel involved, it would appear that it is not an appropriate test.

1.1 This fire-test-response standard for the comparative surface burning behavior of building materials is applicable to exposed surfaces such as walls and ceilings. The test is conducted with the specimen in the ceiling position with the surface to be evaluated exposed face down to the ignition source. The material, product, or assembly shall be capable of being mounted in the test position during the test. Thus, the specimen shall either be self-supporting by its own structural quality, held in place by added supports along the test surface, or secured from the back side.[i/]

Testing on this material:


4.1 This test method is intended to provide only comparative measurements of surface flame spread and smoke density measurements with that of select grade red oak and fiber-cement board surfaces under the specific fire exposure conditions described herein.

https://www.astm.org/standards/e84

 

[woodferret]

The fiberboard and red oak are used as calibration points to which everything else is judged. 

Horizontal surface spread is used in this manner to trap heat and fumes.  This exacerbates fire spread in that auto-ignition and flash-point feed the continuation of the fire, and spread.  A vertical wall, while it may exhibit 'pretty' flame spread, may not burn as intensely due to how vapors rise, etc etc.  Think of how many times you've burned something vertically to have it run out of fuel because the advancing front is beyond the bulk of the material.

From an 2006 IBC standpoint (falling under Interior Finishes), it's the horizontal spread that is the most dangerous, as the primary concern is to minimize the ability of a building to trap its inhabitants as it spreads from room to hallways.  There's a table (803.5) that lays out the class restrictions based on sprinkler availability, occupancy type, and whether it's a room, hallway, or exit.  The exit being the most stringent for obvious reasons.

edit: I went into the weeds.  We can just chalk it up to industry vs layman jargon mismatch.  People buying Medite FR are beholden to the architect's specs, just as we have various VOC requirements as well.

 

[Packard]

My only point was that our perception of the term “fire resistant” might not square up with the specific meaning of the term.  And that term might have different meanings according to the specific standard.