• (Edited )

Hi Ariana,

The # of toilets is determined by the occupancy load.  First you determine the use group, using chapter 3 of the IBC.  Then using this chart from ch 10 of the IBC, you determine the occupancy load per sf.  The the overall sf of the space is going to determine the #s. For an office, using the table below, the occupant load is 150sf gross.  (gross means toilet rooms, hallways, the entire space is included).  The toilets would not add to that total.

Does that make sense?

Rebekka O'Melia, R.A., NCARB, B. Arch, M. Ed, NOMA, Step UP ARE 5.0 Courses

• Under the IBC the only things excluded from floor area gross are vent shafts, courts, and exterior walls. Restrooms are included in the gross square footage.

• The discussion at this thread may help:

Gang Chen, Author, AIA, LEED AP BD+C (GreenExamEducation.com)

• Would the same concept for calculation apply to corridors in the building? For example, calculating the occupancy load for an office building, do we include the area of the corridors or exclude it?

• Hi Sheu,

You should read the entire Ch 10 Mean of Egress from the IBC.  Your question was already answered in my comment above and others.  The gross sf would be determined before the hallways are designed even.  Even the net sf of a rentable area would include corridors, or a factor for a tenant's portion of the corridros.  I think reading the entire chapter 10 of the IBC will help you.  In fact, I think you should be reading preceding chapters of the IBC first in order to understand ch 10.

Rebekka, R.A., NCARB, B. Arch, M. Ed, Step UP ARE 5.0 Courses