# Occupancy Types & Uses To Fixture Counts



## EasilyConfused (Mar 26, 2016)

Would this statement be accurate:

Occupancy TYPES determine fixture counts & Occupancy USES determine occupant LOADS for purposes of establishing egress requirements+.

On the surface this seems simplistic but here's why I'm asking.

Been through this before but.....

I have a Mixed Use non-Separated plan that's 1/2 A-3 and 1/2 B. Within the B space there are additional spaces, that for purposes of establishing ROOM occupancies by USES, would be classified as assembly (use), storage (use), kitchen (use). So even though they have differentiated USES, they are all still technically B by code because meet size requirements.

Have been struggling with coming up with a graphic that incorporates this info into a Life Safety Plan and will help me understand what I have done and therefor better explain to the building official what my thought process was at the time.

Idea is I take my plan and assign both a Occupancy Type & a Occupancy Use to each room. Sounds simple enough.

Some room types:

Large Meeting Room- OT= A-3, OU= Assembly

Offices/Toilets/Corridors etc- OT= B, OU= Business

Storage Room- OT= B, OU= Storage

Serving Kitchen- OT = B, OU= Kitchen

Lab- OT= B, OU= Educational

Small Conference Room- OT= B, OU= Assembly

This makes sense to me.

But here's the problem.

My understanding (and thus the 1st question) would be that to figure occupant loads for the building, I would take the individual rooms (and possibly a combination of spaces toilets, offices, corridors etc for some of the B spaces), look at the USE, then divide the area of the space by it’s use factor to determine the occupant load of that space. Add all the individual occupant loads together for a total building occupant load.

If this is correct, then I’m comfortable with this up until this point.

But now I need to do my fixture counts. And technically, I only have two occupancy TYPES, A-3 & B (mixed use).

Here’s where it falls apart for me.

To be able to do my fixture counts I need to know the number of occupants so I can split between male and female apply factors and arrive at counts. Additionally, the fixture counts are tied to Occupancy Type and not USE.

So, when I look at my plan, it SEEMS that the only way to calculate the occupant loads based on occupancy TYPE is to apply some factor to the two “global” A-3 & B occupancy types, since the “nested” Uses within the B Occupancy type are not types because they are USES, and therefor do not apply to the fixture table.

So, I’m thinking that for the Global A-3 Area I would divide the total area by 15N, and for the global B area I would divide the total area by 100G even though within the business area, because of different USE types, factors would be different for nested spaces within the global business area.

If this is accurate, then this would mean that occupancy uses have no bearing on fixture types.

The other thing that this would mean is that I could/would have different total occupant loads for the global business area for purposes of fixture counts vs total occupant loads for the business part of the project when individual USES are taken into consideration and then added together.

So, thus my reasoning that Occupancy TYPES determine fixture counts & Occupancy USES determine occupant LOADS for purposes of establishing egress requirements+.


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## cda (Mar 26, 2016)

I think you are over thinking again.

Cannot talk to the potty

I want to say normally the terms you use occupancy type and occupancy use are the same


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## cda (Mar 26, 2016)

Look down almost to the bottom, for an example

http://specsandcodes.typepad.com/the_code_corner/code-data/


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## RLGA (Mar 26, 2016)

To use the IBC terminology, it is OCCUPANCY GROUPS (per IBC Chapter 3) and FUNCTION OF SPACE (per IBC Table 1004.1.2). For each portion or portions of a building with the same OCCUPANCY GROUP, I would total up the occupant loads (which are based on FUNCTION OF SPACE) and use that occupant load total to determine the number of plumbing fixtures for the OCCUPANCY GROUP.

Here's an example from my book (unfortunately it doesn't use any storage occupancy groups, but the concept would be the same for all storage rooms in the building):

*Calculation for Mixed Occupancies*

*Given: Hotel building with Group A-2, B, M, and R-1 occupancies.*

*Step 1: Determine number of occupants for each sex.*

*Group A-2:* 500 total occupants/2 = 250 males and 250 females

*Group B:* 75 total occupants/2 = 37.5 males and 37.5 females

*Group M:* 50 occupants/2 = 25 males and 25 females

*Sleeping Units:* 150

*Step 2: Calculate the number of water closets using the ratios for each applicable occupancy group per IBC Table 2902.1.*

*Group A-2:* Ratios are 1 per 125 (males) and 1 per 65 (females)

*Males:*

 250 x 1/125 = 2 water closets



*Females:*

 250 x 1/65 = 3.8 water closets

*Group B: *Ratios are 1 per 25 (for first 50) and 1 per 50 (for remainder exceeding 50)

*Males:*

 37.5 x 1/25 = 1.5 water closets



*Females:*

 37.5 x 1/25 = 1.5 water closets

*Group M:* Ratio is 1 per 500

*Males:*

 25 x 1/500 = 0.05 water closet



*Females:*

 25 x 1/500 = 0.05 water closet

*Group R-1:* Ratio is 1 per sleeping unit = 150 water closets

*Sum of Ratios:*

*Males:*

 2 + 1.25 + 0.05 = 3.3, round up to 4 water closets



*Females:*

 3.8 + 1.5 + 0.05 = 5.35, round up to 6 water closets



*Sleeping Units:*

 150 water closets

*Step 3: Calculate the number of lavatories using the ratios for each applicable occupancy group per IBC Table 2902.1.*

*Group A-2:* Ratio is 1 per 200

*Males:*

 250 x 1/200 = 1.25 lavatories



*Females:*

 250 x 1/200 = 1.25 lavatories

*Group B: *Ratios are 1 per 40 (for first 80) and 1 per 80 (for remainder exceeding 80)

*Males:*

 37.5 x 1/40 = 0.94 lavatory



*Females:*

 37.5 x 1/40 = 0.94 lavatory

*Group M:* Ratio is 1 per 750

*Males:*

 25 x 1/750 = 0.03 lavatory



*Females:*

 25 x 1/750 = 0.03 lavatory

*Group R-1:* Ratio is 1 per sleeping unit = 150 lavatories

*Sum of Ratios:*

*Males:*

 1.25 + 0.94 + 0.03 = 2.22, round up to 3 lavatories



*Females:*

 1.25 + 0.94 + 0.03 = 2.22, round up to 3 lavatories



*Sleeping Units:*

 150 lavatories

*Step 4: Calculate the number of drinking fountains using the ratios for each applicable occupancy group per IBC Table 2902.1.*

*Group A-2:* Ratio is 1 per 500 (Use total occupant load)

500 x 1/500 = 1 drinking fountain

*Group B:* Ratio is 1 per 100 (Use total occupant load)

75 x 1/100 = 0.75 drinking fountain

*Group M:* Ratio is 1 per 1,000 (Use total occupant load)

50 x 1/1000 = 0.05 drinking fountains

*Group R-1:* Not required

*Sum of Ratios:* 1 + 0.75 + 0.05 = 1.8, round up to 2 drinking fountains

*Step 5: Provide the number of service sinks for each occupancy per IBC Table 2902.1.*

1 service sink (Provided all occupancies have access to the service sink)

*Step 6: Provide the number of bathtubs or showers for each occupancy per IBC Table 2902.1.*

*Group R-1:* Ratio is 1 per sleeping unit = 150 bathtubs or showers


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## mark handler (Mar 27, 2016)

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## cda (Mar 27, 2016)

> To use the IBC terminology, it is OCCUPANCY GROUPS (per IBC Chapter 3) and FUNCTION OF SPACE (per IBC Table 1004.1.2). For each portion or portions of a building with the same OCCUPANCY GROUP, I would total up the occupant loads (which are based on FUNCTION OF SPACE) and use that occupant load total to determine the number of plumbing fixtures for the OCCUPANCY GROUP.Here's an example from my book (unfortunately it doesn't use any storage occupancy groups, but the concept would be the same for all storage rooms in the building):
> 
> *Calculation for Mixed Occupancies*
> 
> ...


What he said!!!


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## EasilyConfused (Mar 27, 2016)

Mark & CDA- Ordered Ron's book last week! Anxiously awaiting my copy.

Ron- This is HUGE!

"_To use the IBC terminology, it is OCCUPANCY GROUPS (per IBC Chapter 3) and FUNCTION OF SPACE (per IBC Table 1004.1.2). For each portion or portions of a building with the same OCCUPANCY GROUP, I would total up the occupant loads (which are based on FUNCTION OF SPACE) and use that occupant load total to determine the number of plumbing fixtures for the OCCUPANCY GROUP."_

AND exactly what I was hoping to get to with the question.

Thanks for correcting my terminology as well. Will incorporate changes into my life safety plan.

Your example is gravy.

This all makes sense now and wondering why it was so difficult for me to come to terms with this.

Thanks so much.


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## cda (Mar 27, 2016)

> Mark & CDA- Ordered Ron's book last week! Anxiously awaiting my copy.Ron- This is HUGE!
> 
> "_To use the IBC terminology, it is OCCUPANCY GROUPS (per IBC Chapter 3) and FUNCTION OF SPACE (per IBC Table 1004.1.2). For each portion or portions of a building with the same OCCUPANCY GROUP, I would total up the occupant loads (which are based on FUNCTION OF SPACE) and use that occupant load total to determine the number of plumbing fixtures for the OCCUPANCY GROUP."_
> 
> ...


You can still become a sawhorse!!!!


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