Mixed Occupancy F-1, A-3, B, sprinklered, IIB, Non-separated

[Kmarie039]

I have an existing F-1/B building that is partially sprinklered (currently separated with a 3-hr fire barrier). Total 36,370sf. We are going to sprinkler the whole building as we technically have a COO in expanding F-1 into the current non-sprinklered portion of the building that is open space. There is office space that is also getting expanded into the leftover open space (B). They want to add a large break room that is most likely going to be more than 750sf or 50 persons. I have a few questions....

1) Now that the whole building is sprinklered, we should not need the 3-hr. fire barrier and would be able to punch some holes into it to open up the new F-1 space to the existing?

2) Since my break room is going to be larger than what is allowed under a B occupancy, I would need to consider it an A-3 (most likely will be around 1,000-1,300sf. Would the provisions of 508.3 for non-separated occupancies apply? We are under the A-3, sprinklered, IIb area of 38,000sf? Could it be considered accessory to the F-1 since that is the main purpose of the building?

F-1: 25,490sf
A-3: 1,300sf
B: 7,000sf
S-1: 2,580sf (this is in the basement, constructed of block walls and a precast plank floor)
Total building area: 36,370sf

 

[Tim Mailloux]

I have an existing F-1/B building that is partially sprinklered (currently separated with a 3-hr fire barrier). Total 36,370sf. We are going to sprinkler the whole building as we technically have a COO in expanding F-1 into the current non-sprinklered portion of the building that is open space. There is office space that is also getting expanded into the leftover open space (B). They want to add a large break room that is most likely going to be more than 750sf or 50 persons. I have a few questions....

1) Now that the whole building is sprinklered, we should not need the 3-hr. fire barrier and would be able to punch some holes into it to open up the new F-1 space to the existing?

2) Since my break room is going to be larger than what is allowed under a B occupancy, I would need to consider it an A-3 (most likely will be around 1,000-1,300sf. Would the provisions of 508.3 for non-separated occupancies apply? We are under the A-3, sprinklered, IIb area of 38,000sf? Could it be considered accessory to the F-1 since that is the main purpose of the building?

F-1: 25,490sf
A-3: 1,300sf
B: 7,000sf
S-1: 2,580sf (this is in the basement, constructed of block walls and a precast plank floor)
Total building area: 36,370sf

I would first look to see if you could classify the A3 break room as an accessory occupancy to the B Occupancy.

 

[steveray]

I would first look to see if you could classify the A3 break room as an accessory occupancy to the B Occupancy.

In all fairness...I would let them call it as accessory to the F1 and/or B

 

[Kmarie039]

I would first look to see if you could classify the A3 break room as an accessory occupancy to the B O

In all fairness...I would let them call it as accessory to the F1 and/or B

This is my hope, but I may just need to consult a code reviewer.

 

[Tim Mailloux]

In all fairness...I would let them call it as accessory to the F1 and/or B

if its a break room for both the occupants of the F1 and B occupancies I don't see why it couldn't be accessory to both

 

[walker.t]

Would the provisions of 508.3 for non-separated occupancies apply?

Yes, your building qualifies as nonseparated occupancy.

For all occupancies you listed, the allowable area for those occupancies in a single-story Type IIB sprinklered building exceeds the total area of the building:

	Actual Area	Allowable Area
A-3	1300 s.f.	38,000 s.f. (most restrictive area)
B	7000 s.f.	92,000 s.f.
F-1	25,490 s.f.	62,000 s.f.
S-1	2580 s.f.	70,000 s.f.
Total Actual Area:	36,370 s.f.

Because the total building area is less than the allowable area of the most restrictive occupancy (A-3) you have non-separated occupancy per 508.3.

Could it be considered accessory to the F-1 since that is the main purpose of the building?

As long as your total accessory occupancy area is less than 3627 s.f. you can call it accessory to the primary occupancy of the building. But I can’t think of any reason why you’d want to establish an accessory occupancy relationship, there are other occupancies that exceed 10% of the floor area so there’s no way to get around having multiple occupancies in the building.

1) Now that the whole building is sprinklered, we should not need the 3-hr. fire barrier and would be able to punch some holes into it to open up the new F-1 space to the existing?

Maybe you meant to call the “fire barrier” a “fire wall,” but you don’t need a rated separation wall in the building now because it qualifies for nonseparated occupancy.

 

[Kmarie039]

Yes, your building qualifies as nonseparated occupancy.

For all occupancies you listed, the allowable area for those occupancies in a single-story Type IIB sprinklered building exceeds the total area of the building:

	Actual Area	Allowable Area
A-3	1300 s.f.	38,000 s.f. (most restrictive area)
B	7000 s.f.	92,000 s.f.
F-1	25,490 s.f.	62,000 s.f.
S-1	2580 s.f.	70,000 s.f.
Total Actual Area:	36,370 s.f.

Because the total building area is less than the allowable area of the most restrictive occupancy (A-3) you have non-separated occupancy per 508.3.


As long as your total accessory occupancy area is less than 3627 s.f. you can call it accessory to the primary occupancy of the building. But I can’t think of any reason why you’d want to establish an accessory occupancy relationship, there are other occupancies that exceed 10% of the floor area so there’s no way to get around having multiple occupancies in the building.


Maybe you meant to call the “fire barrier” a “fire wall,” but you don’t need a rated separation wall in the building now because it qualifies for nonseparated occupancy.

So maybe I'm better off just presenting it as non-separated occupancies (calling it what I guess it really is) since I meet all A-3 requirements as most restrictive.

I was constructed as a fire barrier NOT a fire wall as noted on the previous set of drawings when the addition was put on a few years ago. I had another thread when I initially started designing this project trying to understand how they analyzed the addition as I don't agree with how the addition was put on. It does technically meet code though.

 

[steveray]

So maybe I'm better off just presenting it as non-separated occupancies (calling it what I guess it really is) since I meet all A-3 requirements as most restrictive.

I was constructed as a fire barrier NOT a fire wall as noted on the previous set of drawings when the addition was put on a few years ago. I had another thread when I initially started designing this project trying to understand how they analyzed the addition as I don't agree with how the addition was put on. It does technically meet code though.

The only potential issue with that is possibly the A3 drivers in Ch.9 for fire alarm at least are lower for A3 than F1 and you could need an alarm...

 

[walker.t]

So maybe I'm better off just presenting it as non-separated occupancies (calling it what I guess it really is) since I meet all A-3 requirements as most restrictive.

There’s not a problem having the accessory occupancy, I just don’t see what the advantage to that is in a building that already has other non-accessory occupancies.

The only potential issue with that is possibly the A3 drivers in Ch.9 for fire alarm at least are lower for A3 than F1 and you could need an alarm...

Doesn’t look like manual fire alarms will be required:

1. A-3 occupant load is less than 300 (per 907.2.1.)
2. B has an occupant load of less than 500 and doesn’t have more than 100 occupants above or below the lowest level of exit discharge (907.2.2.)
3. F-1 is on the first floor and doesn’t have 500 or more occupants above or below the level of exit discharge (per 907.2.4.)
4. S only requires manual fire alarms with three or more stories (907.2.10.)

I was constructed as a fire barrier NOT a fire wall as noted on the previous set of drawings when the addition was put on a few years ago.

OK, thought maybe you made a typo but it doesn’t matter now that you can get nonseparated occcupancy.

 

[walker.t]

I had another thread when I initially started designing this project trying to understand how they analyzed the addition

For those who are interested in reading the discussion leading up to this thread…

K

Thread 'Level 2 or Level 3 Alteration or Change of Occupancy'

Mar 3, 2025

Hi All! I am new to this forum but have found it helpful over the last two years as I started my own firm to clarify code issues.

I have an existing 'B' occupancy and F-1 occupancy building, Type IIB building. There is a 3-hour fire barrier separating the original building (non-sprinklered, 9,752SF + 2,500 sf basement) and an addition that was put on in 2022 (sprinklered, 23,800sf). Currently all F-1 operations are in the addition area where it is fully sprinklered. We are reconfiguring their office space as it's outdated and they need more room.
The client just mentioned to me they...

• Kmarie039
• Replies: 17
• Forum: Existing Buildings Codes

 

[steveray]

Doesn’t look like manual fire alarms will be required:

1. A-3 occupant load is less than 300 (per 907.2.1.)

Lets see if we can start a debate:

508.3.1​

Nonseparated occupancies shall be individually classified in accordance with Section 302.1. The requirements of this code shall apply to each portion of the building based on the occupancy classification of that space. In addition, the most restrictive provisions of Chapter 9 that apply to the nonseparated occupancies shall apply to the total nonseparated occupancy area.

If you are non separated, why don't you take the entire OL towards the fire alarm trigger?

 

[walker.t]

Lets see if we can start a debate:

Sounds good!

If you are non separated, why don't you take the entire OL towards the fire alarm trigger?

Because, in regards to Chapter 9 requirements, sometimes we look just at the occupancy, sometimes we look at more than the occupancy, such as the fire area:

903 Automatic Sprinkler Systems…903.2.1.3 Group A-3: three points that look at the area, occupant load, and story of the fire area. That might include occupancies in addition to the A-3 occupancy

907 Fire Alarm And Detection Systems…907.2.1 Group A: this makes reference to just the Group A occupant load. So here we ignore the other occupancies in the nonseparated building.

For this building the occupancies and their fire alarm triggers are:

1. A-3 (per 907.2.1 Group A.)
   • Group A occupant load is 300 or more.
   • Group A occupant load is more than 100 above or below the lowest level of exit discharge.
2. B (per 907.2.2 Group B.)
   • Combined Group B occupant load on all floor is 500 or more.
   • Group B occupant load is more than 100 persons above or below the lowest level of exit discharge.
   • Fire area contains an ambulatory care facility.
3. F-1 (per 907.2.4 Group F.)
   • Group F occupancy is two or more stories in height.
   • Combined Group F occupant load is 500 or more above or below the lowest level of exit discharge.
4. S-1 (per 907.2.10 Group S.)
   • In public- and self-storage occupancies with three or more stories.

In our nonseparated occupancy building, if any of these occupancies required fire alarms then the entire building would need fire alarms, not just in the area with the occupancy that required fire alarms. So if they had an ambulatory care facility, they would need to add fire alarms in occupancies that otherwise would not need fire alarms.

 

[steveray]

There you go ruining all my fun....

Note that generally the fire alarm requirements are based on occupancy and not on fire area. Commentary Figure 907.2 contains the conditions that require where either system must be installed in a building. The extent that an alarm system must be installed in a building once it has been determined that such a system is required is based on several factors. One, if it is the only occupancy in the building, then it would be required throughout the building. Two, if the building is a mixed occupancy, it can either be separated or nonseparated. If the occupancy is separated in accordance with Section 508.4, then the alarm system is only required within that separated portion of the building. If the building is considered a nonseparated, mixed-occupancy building, then Section 508.3.1 states that the code applies to each portion of the building based on the occupancy classification of that space and that the most restrictive provisions of Chapter 9 shall apply to the building or portion thereof in which the nonseparated occupancies are located. Therefore, if you have a Group A occupancy in a nonseparated mixed occupancy (containing other occupancies such as Groups B and M) where the Group A occupancy exceeds an occupant load of 300, then the entire nonseparated mixed occupancy would require the alarm system. Note that Section 508.3.1 focuses on each space to determine occupancy and requirements. Once the occupant load is determined, then any requirements, such as fire alarms, would be required throughout.

 

[walker.t]

There you go ruining all my fun....

Nah, good discussion about the code is always fun!

Note that generally the fire alarm requirements are based on occupancy and not on fire area. Commentary Figure 907.2 contains the conditions that require where either system must be installed in a building. The extent that an alarm system must be installed in a building once it has been determined that such a system is required is based on several factors. One, if it is the only occupancy in the building, then it would be required throughout the building. Two, if the building is a mixed occupancy, it can either be separated or nonseparated. If the occupancy is separated in accordance with Section 508.4, then the alarm system is only required within that separated portion of the building. If the building is considered a nonseparated, mixed-occupancy building, then Section 508.3.1 states that the code applies to each portion of the building based on the occupancy classification of that space and that the most restrictive provisions of Chapter 9 shall apply to the building or portion thereof in which the nonseparated occupancies are located. Therefore, if you have a Group A occupancy in a nonseparated mixed occupancy (containing other occupancies such as Groups B and M) where the Group A occupancy exceeds an occupant load of 300, then the entire nonseparated mixed occupancy would require the alarm system. Note that Section 508.3.1 focuses on each space to determine occupancy and requirements. Once the occupant load is determined, then any requirements, such as fire alarms, would be required throughout.

Nothing I can add to that, I don’t see anything debatable in your response.