Live Load for Roof Areas Used for Assembly

[jayson34]

Hi everyone,

ASCE 7-16 Table 4.3-1 says the roof area used for assembly purposes shall use 100 psf live load, and the load is reducible per 4.8.3. The section cross-references back to 4.7 which says live load shall not be reduced in assembly uses in 4.7.5. I'm confused.

Thanks,
Jayson

 

[Eng16080]

Based on my interpretation of the code (I think you meant ASCE 7-16, not 14, btw), I think that's an error in Table 4.3-1. I would not use the live load reduction.

I see no good reason why the loading for an assembly use on the roof of a building would be any different than an assembly use on a floor. In fact, I would be more worried about the roof structure than the floor under such use, as the roof structure is more likely to be in a worse condition over time due to potential moisture damage.

 

[Aesur]

I agree with Eng16080, this must be an error in the table and should match the section "assembly areas" which doesn't allow reduction.

 

[JoelTXCive]

I would not reduce it either..

 

[jayson34]

Thank you, everyone, for your input.

 

[ProgrammingPE]

"Table 1607.1 - Minimum Uniformly Distributed Live Loads" of the 2018 International Building Code has the same Occupiable Roofs - Assembly Areas category, and it has a footnote that tells you that Live Load Reduction is not permitted.

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[lexpatrie]

If I recall, roof live load exists up to 20 psf, then it switches to live load. Affects your load combinations on lower floors.