IBC Cat II or III with occupancy >300

[STRBeth]

thread507-184821

I am looking at an existing building that is having some changes made along with a small, new addition (seismically isolated). It is a Mercantile area and has an occupancy of 1350 or so. I'm trying to decided if I can justify Building Cat II or if I need to go III. The provision about 300 people congregating in one area is what I am concerned about. I found this older thread helpful, but I really don't have separate rooms - it's a large open grocery store. Any opinions? I can't say a grocery store is really public assembly in the way that a church or auditorium would be.

 

[MiketheEngineer]

It is over 300 - done deal.

People dive out of parking lots into stores just like this during a thunderstorm.

 

[STRBeth]

I guess my hang up is that CAT III states, "whose primary occupancy is public assembly...". It isn't classified as Assembly (group A), but as a Mercantile (group M).

 

[MiketheEngineer]

Agreed - still 300 people and they will be "assembling" in it during a good t-storm -

 

[STRBeth]

Mike, I appreciate your practical opinion. But the more I look at it, the more I'm comfortable with CAT II. Reasons being:
1. It says PRIMARY occupancy is public assembly. I think a grocery sore is primarily mercantile.
2. People need 5 sf of space in an area of assembly for standing room only. If that is the case, a 40'x40' building would permit 300 people to stand with 5 sf of space during a thunderstorm and thus be CAT III. So are all buildings over 40'x40' cat III?

Thanks again.

 

[ajh1]

For both IBC 2009 and IBC 2012, the Cat III language reads:
Buildings and other structures whose primary occupancy is public assembly with an occupant load greater than 300.
...Variety of other definitions- mostly education related.
Any other occupancy with an occupant load greater than 5,000.

Assembly occupancy would be one of the Group A occupancies. A grocery store would fall into Group M - Mercantile. That would carry the 5,000 person limit in my opinion.

 

[MiketheEngineer]

STR -

Stand before a judge and jury and explain your thoughts - while I don't completely disagree with you - I still do!!

300 is 300 whether they are assembling or playing cards or whatever 300 people do when they are ALL together. And God knows what they might be doing!!

 

[DST148]

Although primary occupancy is the key in deciding the building category classification, storage of hazardous materials also needs to be considered.
Per IBC 2006, Section 309.1 - Mercantile occupancies shall include department stores, markets, retail or wholesale stores etc. However, there is a restriction on the quantity of hazardous materials that can be stored to qualify for mercantile occupancy.
Table 414.2.5(1)