Fire Blocking Floor Joists

Building code requires the use of blocking for floor joists that exceed 2 inches in width by 12 inches in depth.

Fire blocking floor joists.

The drywall that is your ceiling is a form of fire blocking. The most often used product is a expanding. Material for fire blocks. The inspector may require you to cover the new insulation with drywall as a fire block or leave some areas uncovered to allow for termite inspections.

Any time a duct plumbing pipe or electrical wire goes through a floor or ceiling it must be sealed around it with some type of fire stop. The block is nothing more than a 2 x 6 or fire rated drywall turned flat and attached to the bottom of the first floor joists. Fire blocking locations 2x fire blocking 2x fire blocking 2x fire blocking stringer header ceiling joist floor joist stair stringers the space between stringers must be separated from the upper story floor joist bays. It acts as a cap at the top of your framed basement wall to contain any fire in the wall long enough to alert the smoke alarms in the basement see illustration at bottom.

Blocking also needs to be provided at the supporting end of a joist. Section r502 10 of the international residential code states that header joists can be the same size as the floor joists when the header joist span isn t greater than 4 feet but if the header joist span is more than 4 feet you ll need to double the header joist and ensure that it s capable of. Rigid foam is the best insulation for rim joists. Landings if the area underneath the landing is unfinished the wall bays must be blocked.

Floor joist floor above solid sawn or i joist w attached ceiling ceiling finish material space between each floor joist 1 000 sf solid sawn joists or other solid joists such as i joists provide more than adequate draftstoppingwhen the ceiling finish is added to the bottom of the joists. Fire blocking designed to slow down the spread of fire from one floor of your house to the next. Additional support for the floor joists is achieved by nailing the ends of the joists into headers. You can insulate second floor rim joists following the same steps shown here if you happen to tear out a ceiling during remodeling.

The 2012 international residential code allows for the use of materials other than standard lumber although i do not recommend any of. The blocks must be as wide as the wall. For a 2 x 4 wall use a 2 x 4 block for a 2 x 6 wall use a 2 x 6 block. In addition to providing lateral support blocking helps transfer weight to adjacent joists so that the floor acts as a unified system.