Occupancy Type on Specific Story of a Building

[C Calvano]

2015 IBC, Seattle amendments.
I have a Type II-B, fully sprinklered, B occupancy, 4 story building. There is a separated A-3 occupancy on the 3rd story. In Seattle amendments, there is an exception that no separation is required between groups A-2 or A-3 and Groups B and M occupancies when both are protected with an automatic sprinkler system. Per Table 504.4, the B occupancy can be 4 stories and the A-3 occupancy can be 3 stories. Is the building allowed to be 4 stories as long as the A-3 occupancy is on a story no higher than the 3rd story?

 

[RLGA]

Yes.

 

[Tim Mailloux]

2015 IBC, Seattle amendments.
I have a Type II-B, fully sprinklered, B occupancy, 4 story building. There is a separated A-3 occupancy on the 3rd story. In Seattle amendments, there is an exception that no separation is required between groups A-2 or A-3 and Groups B and M occupancies when both are protected with an automatic sprinkler system. Per Table 504.4, the B occupancy can be 4 stories and the A-3 occupancy can be 3 stories. Is the building allowed to be 4 stories as long as the A-3 occupancy is on a story no higher than the 3rd story?

Is this building separated mixed use or non-separated mixed use? Type IIB construction is unprotected, leading me to believe that the building is non-separated mixed use.

If the building was separated mixed use what you propose would be fine. But if the building is non-separated mixed use the allowable height and area of the building is based on the most restrictive height and area of all the use groups present in the building, see IBC section 508.3.2.

 

[C Calvano]

This building is a separated mixed use so it appears we are okay with having the A occupancy on the third floor.

 

[Tim Mailloux]

This building is a separated mixed use so it appears we are okay with having the A occupancy on the third floor.

in your original post you said the building was type 2B construction (unprotected), so how is the entire floor that's an A-3 occupancy separated from the floors of B occupancy above and below? The floor of the A-3 occupancy would need to be fore rated as wall as the floor of the B occupancy above, and those rated floors would need to be supported fire rated structure. I would then think the building would need to be 2A construction.

 

[steveray]

Tim....

In Seattle amendments, there is an exception that no separation is required between groups A-2 or A-3 and Groups B and M occupancies when both are protected with an automatic sprinkler system.