fire rating of ceilling

[Nitsugua]

I'm investigating on a fire in a two story retirement house. The attic was the main way for the fire to communicate to other locations in the same building, starting from an individual room at the second floor.

Canadian Construction Code indicate that, for that particular room, a 30 minutes fire resistance is required. I can't find the exact fire rating of the ceiling to check this out. Many data are impossible to find after many rechearches.

The ceiling is built that way, starting from below:
-Gypsum bord Firecore "C" 1/2 in
-wood furring 1x3@16in c/c creating an air gap of 3/4 in
-vapour barrier of craft paper
-natural fiberboard 7/16 in (known as Tentest,KB or Donnacona)
-WoodTrusses at 24 inches apart
-Fiberglass insulation between woodtrusses

All I know is that a 1/2in gypsum bord, type X, has a value of 25 minutes but it depends greatly of the orientation of the pannel to the furring in a manner so the edge is fully supported. Firecore C boards must have a greater value for the same thickness. What is it?

Is the air gap over the gypsum good or bad?

Is fiberbord unnacceptable in a firerated ceiling? I never saw it in any typical drawing or description about fire resistance.

Any link will be helpfull.


Luc Perron, engineer
Unigec Experts-conseils