Depending on what code you are working under, this is from the 2018 International Residential Code
R302.11 Fireblocking. In combustible construction, fireblocking shall be provided to cut off both vertical and horizontal
concealed draft openings and to form an effective fire barrier between stories, and between a top story and the roof
space.
Fireblocking shall be provided in wood-framed construction in the following locations:
1. In concealed spaces of stud walls and partitions, including furred spaces and parallel rows of studs or staggered
studs, as follows:
1.1. Vertically at the ceiling and floor levels.
1.2. Horizontally at intervals not exceeding 10 feet (3048 mm).
2. At interconnections between concealed vertical and horizontal spaces such as occur at soffits, drop ceilings
and cove ceilings.
3. In concealed spaces between stair stringers at the top and bottom of the run. Enclosed spaces under stairs
shall comply with Section R302.7.
4. At openings around vents, pipes, ducts, cables and wires at ceiling and floor level, with an approved material
to resist the free passage of flame and products of combustion. The material filling this annular space
shall not be required to meet the ASTM E136 requirements.
5. For the fireblocking of chimneys and fireplaces, see Section R1003.19.
6. Fireblocking of cornices of a two-family dwelling is required at the line of dwelling unit separation.
