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Basment fireblocking

hammerdown22's Avatar

Join Date: Oct 2010
Posts: 245

04-08-16, 10:08 AM   #1  
Basment fireblocking

Is it accepted to use sheet metal for fireblocking? What thickness? It would be great if a roll to flashing could be used and staple it up as you go but I am thinking it is too thin even though it would stop airflow.

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CarbideTipped's Avatar
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Join Date: May 2015
Posts: 3,138

04-08-16, 10:31 AM   #2  
These are IRC approved firestop materials:

•2-inch nominal lumber (2×4, 2×6, 2×8, etc.)
•double layer of 1-inch nominal lumber (1×4, 1×6, 1×8, etc.)
•3/4″ (22/32″) OSB, or double layer of 1/2″ (7/16″) OSB
•3/4″ particle board
•1/2″ drywall
•1/4″ cement board
•mineral or rock wool, installed securely in place
•unfaced fiberglass batt insulation, tightly packed

If you use a double layer the joints need to be offset. Single layer joints need to be backed up with another piece of the same material (or lined up with a joist, for example).

The above is residential; commercial is different, and your local code may be different.


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hammerdown22's Avatar

Join Date: Oct 2010
Posts: 245

04-12-16, 07:42 PM   #3  
Drywall fireblocking in basement walls

If you use 1/2 in drywall to the floor joists above before I frame the walls would I need to be concerned about mold growing on this freblock paper? Top of Basement walls are covered with either roxul or xps.

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