If a 2-hour fire barrier wall extends 1 story from floor to roof deck in a Type II-B building, does the roof structure that the top of this wall is attached to now require a fire resistance rating? In Table 601, Type II-B Roof Structure typically would not. Does "supporting construction" really only refer to structure below the fire barrier?
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Section 707.5.1 Supporting Construction
- Thread starter BillB
- Start date
steveray
SAWHORSE
I tried fighting that fight and the answer was "gravity load supporting" not bracing as a roof might be....don't love it, but that is where it led at the time and we are only getting less safe with that stuff these days...
jj1289
SAWHORSE
This is from the IBC commentary to section 707.5.1
In general, fire barriers must be supported by construction having an equivalent fire-resistance rating. If the supporting structure is a primary structural frame (see the definition in Chapter 2) and supports a fire barrier wall more than two stories in height, the fireresistance rating for the supporting structure must be protected by the individual encasement method in Section 704.3. If the supporting members are a secondary structural member, then the supporting structure can be protected by a membrane as in Section 711 for horizontal assemblies. The intent of this requirement is to prevent the effectiveness of the assembly from being circumvented by a fire that threatens the supporting elements. The requirement for the supporting construction to be fire-resistance rated applies to buildings of all types of construction, even to buildings of Type IIB, IIIB and VB construction for all fire barrier walls except those separating incidental use areas.
In general, fire barriers must be supported by construction having an equivalent fire-resistance rating. If the supporting structure is a primary structural frame (see the definition in Chapter 2) and supports a fire barrier wall more than two stories in height, the fireresistance rating for the supporting structure must be protected by the individual encasement method in Section 704.3. If the supporting members are a secondary structural member, then the supporting structure can be protected by a membrane as in Section 711 for horizontal assemblies. The intent of this requirement is to prevent the effectiveness of the assembly from being circumvented by a fire that threatens the supporting elements. The requirement for the supporting construction to be fire-resistance rated applies to buildings of all types of construction, even to buildings of Type IIB, IIIB and VB construction for all fire barrier walls except those separating incidental use areas.
steveray
SAWHORSE
On the upside, this would just about do away with unrated construction....On the downside this would just about do away with unrated construction....If you had to rate the previously unrated roof all the way down to a foundation....I have a much longer rant for this, but I will leave it for now.... 