How to install basement fire blocking.?

Question

Hi,

I'm building out my basement and as per code need to install fire blocking on the basement ceiling that extends from the masonry wall to the front of the top plate.

My questions are:

1> Is it enough to cut lengths of 3/4 plywood 3" (width of top plate) + 1/2" gap between wall and studs. and nail it to the floor joists above. or do I need to put in bigger widths of plywood.

2> If I extend the plywood further into the room than the front edge of the top plate, wont that interfere with the installation of ceiling sheetrock?

Answer 1

Per the IRC, acceptable materials for this would be 2x lumber, 2 layers of 3/4" lumber or plywood, 5/8" Type "X" drywall, or rock wool. The Code also allows you to use unfaced fiberglass insulation that fills the entire wall cavity 16" in both directions (measured from the top plate).

We don't require this in the town I inspect for, if the ceiling of the basement is dry walled, or has fire-rated lay-in tiles. We feel that allowing the air behind the drywall to circulate a little will prevent any mold contamination.

Check with your local Building Inspector regarding acceptable installations; he won't design it for you, but he will let you know what is, and isn't required or accepted.