Structural frame protection for type 5A construction

[Enginerd]

If a building is constructed of type 5A construction, the structural frame needs to have 1 hour protection per T601 (2009 IBC).

If the 1 hour protection of the structure is provided by the details incorporated in UL U356, 1 layer of 5/8 drywall, do the window and door jambs have to be 'wrapped' with the drywall as well?

The drywall has a 20 minute finish rating (T721.2.1.4(2)). The architect is proposing to add an additional jack stud instead of wrapping the drywall. He is claiming equivalent protection, and using T721.6.2(2) - assigned contribution for wood frame, as his reasoning. This table lists a wood stud wall with min. 2x4 studs @ 16" oc providing 20 mins of fire protection in the assembly.

I see the reasoning, but can not convince myself that this is in fact equivalent. This isn't an issue of providing a protected opening, rather does it provide equivalent protection of the structural frame?

Thank you for your time and expertise.

 

[RLM-Architect]

The doors and windows are not "structural elements" that require individual protection.

If a door or window is in a fire resistance rated wall, then the individual door or window would be required to have a listed rating such as 20, 45, 60 , 90, etc minute rating as an opening protective in the rated wall.

This has nothing to do with the rating of structural elements required by Construction Type.

Typically, fire resistance rated walls (and horizontal assemblies such as floors) have their ratings required by separation requirements of compartments.

See IBC Tables 601 and 602 for rating requirements for construction types but Table 508.4 if you are separating occupancy classifications.

 

[steveray]

I would have to look at the equivalency stuff, but yes the entire structural frame needs to be protected...Including the jackstuds and headers which hold up the floors and roof above....

 

[mtlogcabin]

602.1

Where required to have a fire-resistance rating by Table 601, building elements shall comply with the applicable provisions of Section 703.2.

703.2

Materials and methods of construction used to protect joints and penetrations in fire-resistance-rated building elements, components or assemblies shall not reduce the required fire-resistance rating .

He can use equivilant protection.

 

[Architect1281]

The wall structure construction must be a 1 hour assembly, Yes wall studs, cripples, Jack, king studs, and headers are WALL STRUCTURE -

those elements which keep the wall in place, the only time one would treat the inner jambs as rated would be if the openings were close enough to other construction or property lines per ch 7 exterior wall ratins to be a "Protected opening"