How do you separate two different occupancies where no separation is required. :)

[Ryan Schultz]

If you want to separate (B) from (S-1) per the following table, do you interpret it as it needs to be separated, but the separation is 0 rated?

Or do you interpret it as it doesn't need a separation at all (that is no physical barrier at all)?

...


I ask because I have a type VB where I'd like to separate these 2 occupancies, so the (B) can be 2 stories, and the (S-1) can be 1 story.

If they were nonseparated, the entire building would have to be 1 story. Do you see my confusion? The following code snippets adds to the confusion.

• e. Separation is not required between occupancies of the same classification.
• N = No separation requirement.
  
  
  If the interpretation is for separation, but it can be 0 rated, than i feel... N = Separated, but 0 rated.
  
  
  https://up.codes/viewer/wisconsin/ibc-2015/chapter/5/general-building-heights-and-areas#table_508.4
• 

 

[Yankee Chronicler]

If no separation is required ... no separation is required [by the code]. If the owner or tenant(s) want to introduce some kind of physical separation, that's up to them -- and it can be any materials allowed in the type of construction but does not have to be rated. It's just a physical separation, not a fire separation.

You can't have part of a building be a one story building and another part be a two story building. One part may physically be only one story in height, but the building is a two-story building. If you want to split it up so that different allowable heights and areas apply, then you need to introduce a firewall between the two portions of the structure so you can analyze them independently.

 

[Yikes]

Please explain why you want the S-1 to be only one story. What does it accomplish for you?

I’ve had many apartment designs where there was an “A” occupancy recreation room on the ground floor, and “R” occupancies up to the 4th floor.

 

[Ryan Schultz]

Thank you.

Something doesn't align for me.

Hypothetically, if you had an unsprinklered mixed-used Type VB with (B) and (A-2) occupancies, you could use a 2 hr fire barrier, so the (B) could be 2 stories and the (A-2) could be 1 story.

Now if you take (B) and (S-1), which has less of a fire risk delta between them than the (B) and (A-2) does, you now have to use a fire wall (instead of fire barrier)? Conceptually that doesn't make sense in my head.

Perhaps i'm missing something.

 

[Yankee Chronicler]

Thank you.

Something doesn't align for me.

Hypothetically, if you had an unsprinklered mixed-used Type VB with (B) and (A-2) occupancies, you could use a 2 hr fire barrier, so the (B) could be 2 stories and the (A-2) could be 1 story.

No. This is where you aren't understanding or applying the code correctly.

Allowable height and area are regulated based on the building, not on portions of a building. One building can't be partially classified as one story and partially classified as two stories. If any part of a building is two stories -- the building is two stories. Occupancy separations (fire barriers) do not split a building into two buildings, they only separate occupancies within the same building.

In order to treat the height and area as two separate buildings, the separation has to be a firewall -- meeting the structural and construction requirements for a firewall.

 

[Ryan Schultz]

Thank you, but i'm still don't quite understand, per the following, i thought if you separated occupancies per Section 508, that each occupancy area could realize their individually allowed number of stories.

Again, perhaps my interpretation is wrong.

Chapter 5 General Building Heights and Areas: Wisconsin Building Code 2015 | UpCodes

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"In a building containing mixed occupancies in accordance with Section 508, no individual occupancy shall exceed the height and number of story limits specified in this section for the applicable occupancies."

Thank you for your guidance.

 

[Ryan Schultz]

There's also this blurb, from Applying the Building Code: Step-by-Step Guidance for Design and Building Professionals

 

[walker.t]

i thought if you separated occupancies per Section 508, that each occupancy area could realize their individually allowed number of stories.

Yes, that is correct. You are treating them as a single building (therefore no fire wall is required) that has separated occupancies per 508.

My understanding of what you want is:
1. Type VB, unsprinklered building.
2. S-1 on ground floor.
3. B on second floor.

1. Because you want a two-story building and S-1 is limited to 1-story per Table 504.4, you cannot use nonseparated occupancy per 508.3.2 (entire building must meet requirements of the most restrictive occupancy in the building.)
2. You can use separated occupancies as long as S-1 stays on the first floor (the maximum height per Table 504.4), you then need to separate S-1 and B per Table 508.4.

If this is the same project we’ve been talking about on a different thread then your stairs will need to be enclosed and rated because you’ll be penetrating the horizontal assembly between S-1 on the first floor and B on the second floor. [Edit. This is incorrect, no separation required per Table 508.4, see #10.]

There's also this blurb, from Applying the Building Code: Step-by-Step Guidance for Design and Building Professionals

Here’s an image from the 2018 IBC Illustrated Handbook illustrating the concept, the two notes in red are my additions:

 

[Ryan Schultz]

Thank you.

> If this is the same project we’ve been talking about on a different thread then your stairs will need to be enclosed and rated because you’ll be penetrating the horizontal assembly between S-1 on the first floor and B on the second floor.

Indeed it is.

I would assume that internal S-1, since it's less than 10% of the building area, can be an incidential occupancy.

Chapter 5 General Building Heights and Areas: Wisconsin Building Code 2015 | UpCodes

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...

Even if it's not considered an incidental occupancy isn't separation between a B and S-1 - zero rated, per 508.4 (that is, No separation requirement)?

Chapter 5 General Building Heights and Areas: Wisconsin Building Code 2015 | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

 

[walker.t]

Indeed it is.

OK.

I would assume that internal S-1

The link to UpCodes doesn’t work for me, I’m on an older browser that they don’t like.

I’m not sure what you mean by “internal” S-1.

since it's less than 10% of the building area, can be an incidential occupancy.

1. If you mean “incidental” anything, it has to be “incidental use” (not “incidental occupancy”) - incidental uses are a very limited list of uses in IBC 2021 Table 509.1.
2. Maybe you mean “accessory occupancy” per 508.1? If that’s the case you have two things going for you:
a. The general 10% allowable area per 508.2.3.
b. 311.1.1 Accessory Storage Spaces allows a room or space used for storage purposes that is accessory to another occupancy to be classified as part of the primary occupancy. If that’s the case then you have a single occupancy building.

Even if it's not considered an incidental occupancy isn't separation between a B and S-1 - zero rated, per 508.4 (that is, No separation requirement)?

Yes, that’s correct, I forgot your comment about that in #1 and didn’t check it myself before I said you’d need a stair. Table 508.4 says for B and S-1 you need “N” which mean no separation required, you can have them open to each other (literally nothing separating them) or any non-rated construction. Therefore no rated stair is required.

 

[Ryan Schultz]

Yes, sorry, in my mind I was thinking “accessory occupancy”.

Thank you again.

 

[Ryan Schultz]

> I’m not sure what you mean by “internal” S-1.

Meant that S-1 is an accessory occupancy within that B occupancy.

 

[walker.t]

Yes, sorry, in my mind I was thinking “accessory occupancy”.

Thank you again.

You’re welcome, thank you for the clarification.

But regarding S-1, are you sure it’s S-1 and not F-1? Your plan on your other thread has a space with overhead doors labeled as a “Service Area” and labeled as S-1 - it’s the “service area” label that bothers me - what’s really going on in the space? However, Table 508.4 still has “N” between B and F-1, but the occupancy classification should be accurately stated on the plan. If it is F-1 I’d probably consider the B to be accessory to the F-1, but you’re over 10% of the F-1 area so you’d go for separated occupancies just like if it was indeed S-1.

 

[Ryan Schultz]

It's 311.2 Moderate-Hazard Storage, Group S-1
specifically: motor vehicle repair garages complying with the maximum allowable quantities of hazardous materials listed in Table 307.1(1) (see Section 406.8)

 

[Henchalwoog]

!

 

[Yankee Chronicler]

There's also this blurb, from Applying the Building Code: Step-by-Step Guidance for Design and Building Professionals

View attachment 16970

You are conflating where an occupancy can be located within a building, and the allowable height of the building. Section 7.2.3 does not address the height of the building. It addresses on what stories within a building an occupancy can be located.

**A** building is either a one-story building or a two-story building. It can't be both. If any portion of ONE building is two stories, the entire building is a two-story building.

 

[walker.t]

motor vehicle repair garages complying with the maximum allowable quantities of hazardous materials listed in Table 307.1(1) (see Section 406.8)

Sorry for starting to drift from your original question, but does gasoline in the vehicles count towards the limit in Table 307.1(1)? Footnote b says “The aggregate quantity in use and storage shall not exceed the quantity specified for storage.”

If the fuel in the vehicle gas tanks (“in use”?) is included, considering that gasoline is a flammable liquid per the 2021 IBC commentary, weight is 6 pounds/gallon per online research, limit in Table 307.1(1) is 120 pounds, therefore only 20 gallons. My car has 14 gallons with a full tank, two or three vehicles in the service area will probably exceed 20 gallons.

 

[Tim Mailloux]

You are conflating where an occupancy can be located within a building, and the allowable height of the building. Section 7.2.3 does not address the height of the building. It addresses on what stories within a building an occupancy can be located.

**A** building is either a one-story building or a two-story building. It can't be both. If any portion of ONE building is two stories, the entire building is a two-story building.

from the IBC code Illustrated...
…The maximum allowable height in feet is regulated by Table 504.3 primarily by the building’s construction type, with limited regard for the occupancy or multiple occupancies located in the building. However, the maximum allowable height in stories above grade plane can vary significantly based on the occupancy group involved as set forth in Table 504.4. Where multiple occupancies are located in the same building, and the provisions of Section 508.4 for separated occupancies are utilized, each individual occupancy can be located no higher than set forth in the table. See Figure 503-1….

 

[Yankee Chronicler]

from the IBC code Illustrated...
…The maximum allowable height in feet is regulated by Table 504.3 primarily by the building’s construction type, with limited regard for the occupancy or multiple occupancies located in the building. However, the maximum allowable height in stories above grade plane can vary significantly based on the occupancy group involved as set forth in Table 504.4. Where multiple occupancies are located in the same building, and the provisions of Section 508.4 for separated occupancies are utilized, each individual occupancy can be located no higher than set forth in the table. See Figure 503-1….

Right.

This regulates, as I commented above, not how many stories a building is but where in a building certain occupancies may or may not be located. You may, for example, have a four-story building, but certain occupancies cannot be located any higher than the second story.

The mixed us provisions have a formula for calculating the maximum allowable area based on the proportions or ratios of the various mixed uses, but this does not extend to mixing the number of stories in portions of a single building. A building is a two-story building even if only 10% of the footprint is two stories in height.