Load Bearing Metal Stud Walls and Fire Resistance Rating

[sshiffermiller]

Hello, I've had a general question about the concept of fire partitions versus walls that require a fire resistance rating... For example In an apartment building of construction type IB, dwelling units must be separated with 1hr fire partitions. Also, Load bearing walls need to have a 2 hour fire resistance rating. What do you call the load bearing wall? its not a fire partition, right? Because it isn't separating spaces, its simply rated to protect the steel studs.

Thanks for helping me expand my knowledge!

 

[classicT]

See IBC Section 704

704.1 Requirements
The fire-resistance ratings of structural members and assemblies shall comply with this section and the requirements for the type of construction as specified in Table 601. The fire-resistance ratings shall be not less than the ratings required for the fire-resistance-rated assemblies supported by the structural members.

Exception: Fire barriers, fire partitions, smoke barriers and horizontal assemblies as provided in Sections 707.5, 708.4, 709.4 and 711.2, respectively.

 

[Robert]

Hello, I've had a general question about the concept of fire partitions versus walls that require a fire resistance rating... For example In an apartment building of construction type IB, dwelling units must be separated with 1hr fire partitions. Also, Load bearing walls need to have a 2 hour fire resistance rating. What do you call the load bearing wall? its not a fire partition, right? Because it isn't separating spaces, its simply rated to protect the steel studs.

Thanks for helping me expand my knowledge!

fire partitions, fire barriers and fire walls are tested assemblies. They are required in certain conditions (ie: occupancy separations, corridors). If you don't fall into those conditions, the bearing wall may simply be a 2 hour rated wall (not a fire wall, not a fire barrier and not a fire partition).

 

[steveray]

Fire walls, barriers, and partitions contain the spread of fire (which also protects the structure to an extent)...Fire rated construction solely focused on preservation of the structural elements is the most I can simplify it...

 

[RLGA]

There are two types of fire ratings in the building code: fire-rated assemblies and fire-rated construction.

Fire-rated construction, as steveray pointed out, preserves the building structure and is based on construction type per Chapter 6. Fire-rated assemblies, also as steveray pointed out, prevents the spread of fire through the building, and are required to have protected openings and penetrations. Fire-rated assemblies consist of fire walls, fire barriers, fire partitions, smoke barriers, and horizontal assemblies.

When building elements that have multiple functions, then the most restrictive of each function is applicable. For example, a wall that is an interior loadbearing wall and is also a fire partition for dwelling unit separation (as in your case) is providing multiple functions. Since the construction type is IB, a 2-hour rating for interior loadbearing walls is required; however, since the wall is also a dwelling unit separation, then it must also be a 1-hour fire partition. Therefore, we have to consider the most restrictive requirements of both conditions:

• The wall will be required to have a 2-hour rating to protect the construction, but openings are not required to be protected; however,
• The fire partition is also a fire-rated assembly, therefore, openings are required to be protected.

The question now is, what is the required rating for the openings since the wall is of 2-hour-rated construction? Since fire-rated construction is not required to have protected openings, then the opening requirements for fire partitions apply. Thus, a fire partition, which is only required to have a 1-hour rating, can include doors that need only a 1/3-hour rating and penetrations with a 1-hour rating.