Fire-Blocking
CSI Division 06, Wood, Plastics, and Composites
Wood or other approved blocking installed inside concealed stud and joist cavities during framing, specifically to stop fire and smoke from spreading quickly through the hidden, connected void spaces inside a wall or floor system.
Why it matters
This is a different job from [[concept-firestopping|Firestopping]], which seals a penetration, like a pipe or cable passing through an already-finished, fire-rated wall or floor. Fire-blocking happens earlier, during framing itself, closing off the hidden cavities a fire could otherwise travel through undetected before anyone even sees smoke.
On a real project
A framing crew installs fire-blocking at the top and bottom of stud cavities in a stairwell wall, and at other code-required locations, specifically to prevent fire from racing upward through the concealed space behind the finished wall surface.
Who this matters most to
A Carpenter installs fire-blocking as part of the framing scope, and it's one of the specific items an inspector checks for before framing can be covered with drywall.
Where this goes wrong
A framing crew skips fire-blocking in a few concealed cavities to save time, assuming the drywall covering will be inspected and nothing will be checked behind it. A framing inspection catches the gap before the walls close in, requiring the crew to open the wall back up and correct it.