Fire Blocking

Fire blocking is not synonymous with fire stopping. In combustible construction, fire blocking shall be installed to cut off concealed draft openings (both vertical and horizontal) and shall form an effective barrier between floors, between a top story and a roof or attic space. Fire blocking shall be installed in the locations specified in Sections 717.2.2 through 717.2.7 of the Indiana Building Code. Fire blocking is found in non fire-rated wood construction assemblies.

Where to Install
Fire blocking shall be installed at openings around vents, pipes, ducts, chimneys and fireplaces at ceiling and floor levels, with an approved material to resist the free passage of flame and the products of combustion. Factory-built chimneys and fireplaces shall be fire blocked in accordance with UL 103 and UL 127.

In wood-frame construction, fire blocking should be provided in the following locations:
  • Penetrations in the stud walls and partitions at the top plate and floor level (multilevel);
  • Horizontal communication, within a wall, at 10 foot intervals
  • Interconnections between concealed spaces that occur at soffits, drop or cove ceilings;
  • Concealed spaces between stair stringers at the top and bottom of run;
Penetrations of fire blocking - refer to the Indiana Building Code, Penetrations - 712.4.2 Non-fire-resistance-rated assemblies
When a fire block is penetrated for the trades to run their wires, pipes, and other mechanical penetrating items, the integrity of the wood fire blocks is compromised and they must be protected with a material that is equal to or greater than the burn time of the blocking material. The integrity of fire blocks shall be maintained.

Material Needed

Using a material that meets ASTM-E 136 test criteria fulfills the code requirements for fire blocking penetrations because the material is tested and is equivalent in performance to the fire blocking material. Material tested in accordance with ASTM-E 84 and ASTM-E 814 may also maintain the integrity of the fire blocking. (Fire caulk used as a fire blocking material is acceptable) Verification of the material should been done prior to installation. Review with the AHJ.