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Fire blocking
Fire blocking is material installed in wall and floor cavities to slow the spread of fire and smoke.
Why it matters
It buys time in an emergency. It also helps the build pass inspection.
Where people get this wrong
Fire blocking is not the same as insulation. Small gaps at chases and soffits can defeat fire blocking if they are left open.
Real-world example
A small fire starts in a wall cavity. Without fire blocking, that cavity can act like a chimney. Fire blocking helps slow that path so people can get out and firefighters can respond.
Where this hits your build
This shows up during framing. Once walls are up and covered, you lose access. The pre-drywall walkthrough is your window to verify.
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