Assistance with occupancy classification

[ScooterMcGruder]

Hello, This question is for a proposed project located in GEORGIA, using 2018 IBC and the 2024 NFPA 101 Life Safety Code. (this project does not qualify in Georgia as an IRC building).

A proposed 148-unit multi-family development within an approved master development and located on 1 parcel of land. This project consists of 10 individual buildings and a clubhouse with pool. Each of the 10 buildings has 16 dwelling units / 3 stories / 34,440 Square feet / Type V-B construction with sprinklers).

Each of the 10 buildings has 16 dwelling units that are separated by 2-hour fire walls which creates each 2-hour fire separated area into 2 dwelling units that are stacked ( 1 dwelling unit is on the first floor and the second welling unit takes up the second and third floor above, each dwelling unit has their own exterior egress doors)

This design creates separate buildings in accordance with 2018 IBC 503.1 (code listed below).

503.1 General: Unless otherwise specifically modified in Chapter 4 and this chapter, building height, number of stories and building area shall not exceed the limits specified in Sections 504 and 506 based on the type of construction as determined by Section 602 and the occupancies as determined by Section 302 except as modified hereafter. Building height, number of stories and building area provisions shall be applied independently. For the purposes of determining area limitations, height limitations and type of construction, each portion of a building separated by one or more fire walls complying with Section 706 shall be considered to be a separate building.
The architect provided the following letter;
Based on my review of the e-mail chain from the City of Pooler, my understanding of the classification, and requirements of our buildings in reference to the International Building Code with the current Georgia State Amendments and the Life Safety Code (LSC) are as follows:

• Construction type: VB sprinkled (as per IBC)
• Occupancy type: R-3
• Separation: Per IBC 706.1.1, the 2-hour firewall creates independent separation between the 24’ wide duplex occupancy types.
• Two individual separate living spaces per each 24’ wide three-story unit

Based on previous applications of our building assembly and my personal correspondence and many discussions with an International Code Council official, when the units are separated by a two-hour firewall and the building is sprinklered, these are considered two-family dwellings; the above regulations apply. The separation of these units by a two-hour rated wall meets the requirements outlined in 6.1.14.4 of the Life Safety Code which defines separated occupancies.

To the best of my knowledge, this is the correct interpretation of the International Building Code with the current Georgia State Amendments and the Life Safety Code as they apply to this structure. I have attached correspondence from the ICC that references the impact of the 2 hour wall assembly.

I hope this addresses your concerns but please let me know if you need any additional information.

Sincerely,

####### Architects & Designers
In Georgia, the amendments require the Occupancy Classification to be determined using NFPA 101 Life Safety Code based on the Georgia "code reference guide"
My question is, what is the occupancy classification for this design,

NFPA 101 definitions:

6.1.8.1 Definition — Residential Occupancy

An occupancy that provides sleeping accommodations for purposes other than health care or detention and correctional.

6.1.8.1.1* Definition — One- And Two-Family Dwelling Unit

A building that contains not more than two dwelling units, each dwelling unit occupied by members of a single family with not more than three outsiders, if any, accommodated in rented rooms.

6.1.8.1.5 Definition — Apartment Building

A building or portion thereof containing three or more dwelling units with independent cooking and bathroom facilities.

My next questions is should the occupancy classification be determined using the entire building with 16 dwelling units / 3 stories / 34,440 Square feet as an "Apartment Building"? or because the building is separated by the 2-hour fire wall creating 2 dwelling units within each 2-hour separated area should they be classified as "one and two family dwelling units"?

The architect designed the 2-hour wall as a "PARTY WALL" per 2018 IBC 706.1.1 Party Walls: Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

Exceptions:

• Openings in a party wall separating an anchor building and a mall shall be in accordance with Section 402.4.2.2.1.
• Fire walls are not required on lot lines dividing a building for ownership purposes where the aggregate height and area of the portions of the building located on both sides of the lot line do not exceed the maximum height and area requirements of this code. For the code official's review and approval, he or she shall be provided with copies of dedicated access easements and contractual agreements that permit the owners of portions of the building located on either side of the lot line access to the other side for purposes of maintaining fire and life safety systems necessary for the operation of the building.

Thank you for any insight that you can provide,
-Scooter

 

[Yankee Chronicler]

My initial reaction was R-2, but the architect appears to be relying on the fact that the firewalls create a series of eight "buildings" within each structure, and each "building" only has two dwelling units. This could get you into an R-3 classification:

310.4 Residential Group R-3​

Residential Group R-3 occupancies where the occupants are primarily permanent in nature and not classified as Group R-1, R-2, R-4 or I, including:

• Buildings that do not contain more than two dwelling units

It's important to note that IBC 706.1.1 stipulates NO openings in the fire walls.

706.1.1 Party Walls​

Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

"Openings" are different than "penetrations," yet the IBC doesn't define either "opening" or "penetration." In my opinion, if the architect is going to go the route of claiming that each attached duplex is a separate "building" due to the firewalls, that should mean that each duplex has all its utilities come directly into the duplex from the street -- no common feeds running the length of the structure.

BUT -- then you bring NFPA 101 into the mix, and I haven't spent much time in NFPA 101 for quite some time. This makes your question the critical question:

My next questions is should the occupancy classification be determined using the entire building with 16 dwelling units / 3 stories / 34,440 Square feet as an "Apartment Building"? or because the building is separated by the 2-hour fire wall creating 2 dwelling units within each 2-hour separated area should they be classified as "one and two family dwelling units"?

The question is whether NFPA 101 follows the IBC in allowing a structure that is subdivided by firewalls to be considered two (or more) "buildings." The only place this has any effect in the IBC is for determining that maximum allowable floor area. You cited the NFPA 101 definition for "Apartment Buuilding," but you overlooked the fact that this is a subordinate definition under "Building":

3.3.37* Building​

Any structure used or intended for supporting or sheltering any use or occupancy. (SAF-FUN)

So, before we talk about whether an "apartment building" contains three or more dwelling units, we have to determine what the "Building" is. Under NFPA, does each structure consist of eight two-family residences, or is each structure a single "Building" containing 16 apartments/dwelling units? I lean in the direction of saying that NFPA 101 doesn't provide for a single structure to be divided into multiple "buildings" the way the IBC does, so I think under NFPA 101 what you have is a single building that falls under the definition of "Apartment Building."

 

[ScooterMcGruder]

My initial reaction was R-2, but the architect appears to be relying on the fact that the firewalls create a series of eight "buildings" within each structure, and each "building" only has two dwelling units. This could get you into an R-3 classification:



It's important to note that IBC 706.1.1 stipulates NO openings in the fire walls.



"Openings" are different than "penetrations," yet the IBC doesn't define either "opening" or "penetration." In my opinion, if the architect is going to go the route of claiming that each attached duplex is a separate "building" due to the firewalls, that should mean that each duplex has all its utilities come directly into the duplex from the street -- no common feeds running the length of the structure.

BUT -- then you bring NFPA 101 into the mix, and I haven't spent much time in NFPA 101 for quite some time. This makes your question the critical question:



The question is whether NFPA 101 follows the IBC in allowing a structure that is subdivided by firewalls to be considered two (or more) "buildings." The only place this has any effect in the IBC is for determining that maximum allowable floor area. You cited the NFPA 101 definition for "Apartment Buuilding," but you overlooked the fact that this is a subordinate definition under "Building":



So, before we talk about whether an "apartment building" contains three or more dwelling units, we have to determine what the "Building" is. Under NFPA, does each structure consist of eight two-family residences, or is each structure a single "Building" containing 16 apartments/dwelling units? I lean in the direction of saying that NFPA 101 doesn't provide for a single structure to be divided into multiple "buildings" the way the IBC does, so I think under NFPA 101 what you have is a single building that falls under the definition of "Apartment Building."

Thank you! This is very helpful! My opinion since this project was submitted is that it is an apartment building, but it always helps to get further clarification! The NFPA 101 definition of “building” also supports this project to be classified as apartments.

By the way, the project is 1 parcel, private owned by 1 entity and all the units are rentals.

Thanks again!

 

[RLGA]

I must disagree with my friend from the Northeast, to a small degree, regarding the IBC. I do not disagree with his classification per NFPA 101 ("LSC"). The LSC is not a building code, so it does not distinguish between the use of a fire wall and the number of units.

Just before your highlight of Section 503.1, it states, "For the purposes of determining area limitations, height limitations and type of construction..." It does not state occupancy classification as a purpose for fire wall separation, nor does it state that fire walls are used to determine the number of dwelling units in a building. Thus, the entire fire-wall-separated building should be considered as a whole and therefore classified as a Group R-2 building, rather than a series of Group R-3 duplexes. Thus, in my opinion, either way (IBC or LSC), this is a multi-family building consisting of three or more dwelling units.

Also, a "party wall" applies to shared walls that are "located on a lot line." Based on your description of the development, I assume there are no lot lines located at the fire wall locations. If this is correct, they are not "party walls" as described in Section 706.1.1--just fire walls, which do allow limited protected openings.

Although "openings" are not defined, requirements for "openings" are referenced to Section 716, which only addresses protection for doors and windows. Penetrations, joints, and transfer openings are individually referenced to their respective sections; therefore, they are technically not "openings" (except for "air or duct transfer openings," which have their own set of requirements).

 

[Yankee Chronicler]

By the way, the project is 1 parcel, private owned by 1 entity and all the units are rentals.

Yes, and I took that into account, because the language in NFPA 101 includes discussions of party walls that are also property lines. I think if each duplex was on a separate, deeded parcel there could be a better argument that each duplex is a separate building (under NFPA 101). With the entire structure being on a single parcel, I don't think under NFPA they can have eight two-family dwellings,. I think they have a single "apartment building" as defined in NFPA 101.

 

[Tim Mailloux]

from the 2021 IBC Illustrated Handbook....

In this section, the IBC also indicates that fire walls create separate buildings when evaluating for allowable height and area. Defined and regulated under the provisions of Section 706, the function of a fire wall is to separate one portion of a building from another with a fire-resistance-rated vertical separation element. Where a fully complying fire wall is provided, it provides two compartments, one on each side of the wall, which may each be considered under the IBC to be separate buildings for specific purposes. Multiple fire walls may be utilized to create a number of separate buildings within a single structure. The resulting benefit of the use of a fire wall is that the limitations on height, number of stories, and floor area are then addressed individually for each separate building created by fire walls within the structure, rather than for the structure as a whole



503.1.2 Buildings on the same lot.
Where two or more buildings are located on the same lot, they may be regulated as separate buildings in a manner generally consistent with buildings situated on separate parcels of land.

 

[ScooterMcGruder]

I must disagree with my friend from the Northeast, to a small degree, regarding the IBC. I do not disagree with his classification per NFPA 101 ("LSC"). The LSC is not a building code, so it does not distinguish between the use of a fire wall and the number of units.

Just before your highlight of Section 503.1, it states, "For the purposes of determining area limitations, height limitations and type of construction..." It does not state occupancy classification as a purpose for fire wall separation, nor does it state that fire walls are used to determine the number of dwelling units in a building. Thus, the entire fire-wall-separated building should be considered as a whole and therefore classified as a Group R-2 building, rather than a series of Group R-3 duplexes. Thus, in my opinion, either way (IBC or LSC), this is a multi-family building consisting of three or more dwelling units.

Also, a "party wall" applies to shared walls that are "located on a lot line." Based on your description of the development, I assume there are no lot lines located at the fire wall locations. If this is correct, they are not "party walls" as described in Section 706.1.1--just fire walls, which do allow limited protected openings.

Although "openings" are not defined, requirements for "openings" are referenced to Section 716, which only addresses protection for doors and windows. Penetrations, joints, and transfer openings are individually referenced to their respective sections; therefore, they are technically not "openings" (except for "air or duct transfer openings," which have their own set of requirements).

Thank you, this is very helpful!

 

[ScooterMcGruder]

from the 2021 IBC Illustrated Handbook....

In this section, the IBC also indicates that fire walls create separate buildings when evaluating for allowable height and area. Defined and regulated under the provisions of Section 706, the function of a fire wall is to separate one portion of a building from another with a fire-resistance-rated vertical separation element. Where a fully complying fire wall is provided, it provides two compartments, one on each side of the wall, which may each be considered under the IBC to be separate buildings for specific purposes. Multiple fire walls may be utilized to create a number of separate buildings within a single structure. The resulting benefit of the use of a fire wall is that the limitations on height, number of stories, and floor area are then addressed individually for each separate building created by fire walls within the structure, rather than for the structure as a whole



503.1.2 Buildings on the same lot.
Where two or more buildings are located on the same lot, they may be regulated as separate buildings in a manner generally consistent with buildings situated on separate parcels of land.

Lets remove the NFPA 101 (LSC) from a considering factor, based solely on the IBC, a building consisting of 16 dwelling units separated by a 2-hour fire wall thus to create eight two-family residences, is the occupancy classification R2 or R3.

Should I be considering the overall building 34,000 S.F / 3 Stories located on a single parcel with 10 total buildings, a clubhouse with a leasing office / 1 owner and all units are rentals or because of the 20hour party wall is this overall project two family dwellings.... I feel like this could be an IBC loop-hole but my option is these are apartment buildings.

Although, ultimately weather R-2 or R-3 classification, the building height and area seem irrelevant since the design complies with both, in the end the building is sprinklered... what other differences would have a big affect under R-2 vs R-3?

Now, I go back to the primary LSC classification as apartments, this will require ADA accessibility anyway, do you see any big deal accepting the R-2 classification for the sole purpose of determining building height and area or will accepting R-2 trigger other design requirements? (this is a code reference guide designation)

 

[Tim Mailloux]

Are you the architect for this project, or the AHJ doing a plan review?

 

[ScooterMcGruder]

I must disagree with my friend from the Northeast, to a small degree, regarding the IBC. I do not disagree with his classification per NFPA 101 ("LSC"). The LSC is not a building code, so it does not distinguish between the use of a fire wall and the number of units.

Just before your highlight of Section 503.1, it states, "For the purposes of determining area limitations, height limitations and type of construction..." It does not state occupancy classification as a purpose for fire wall separation, nor does it state that fire walls are used to determine the number of dwelling units in a building. Thus, the entire fire-wall-separated building should be considered as a whole and therefore classified as a Group R-2 building, rather than a series of Group R-3 duplexes. Thus, in my opinion, either way (IBC or LSC), this is a multi-family building consisting of three or more dwelling units.

Also, a "party wall" applies to shared walls that are "located on a lot line." Based on your description of the development, I assume there are no lot lines located at the fire wall locations. If this is correct, they are not "party walls" as described in Section 706.1.1--just fire walls, which do allow limited protected openings.

Although "openings" are not defined, requirements for "openings" are referenced to Section 716, which only addresses protection for doors and windows. Penetrations, joints, and transfer openings are individually referenced to their respective sections; therefore, they are technically not "openings" (except for "air or duct transfer openings," which have their own set of requirements).

Lets remove the NFPA 101 (LSC) from a considering factor, based solely on the IBC, a building consisting of 16 dwelling units separated by a 2-hour fire wall thus to create eight two-family residences, is the occupancy classification R2 or R3.

Should I be considering the overall building 34,000 S.F / 3 Stories located on a single parcel with 10 total buildings, a clubhouse with a leasing office / 1 owner and all units are rentals or because of the 20hour party wall is this overall project two family dwellings.... I feel like this could be an IBC loop-hole but my option is these are apartment buildings.

Although, ultimately weather R-2 or R-3 classification, the building height and area seem irrelevant since the design complies with both, in the end the building is sprinklered... what other differences would have a big affect under R-2 vs R-3?

Now, I go back to the primary LSC classification as apartments, this will require ADA accessibility anyway, do you see any big deal accepting the R-2 classification for the sole purpose of determining building height and area or will accepting R-2 trigger other design requirements? (this is a code reference guide designation)

View attachment 16747

Are you the architect for this project, or the AHJ doing a plan review?

I am the AHJ doing the plan review

 

[Yankee Chronicler]

Lets remove the NFPA 101 (LSC) from a considering factor, based solely on the IBC, a building consisting of 16 dwelling units separated by a 2-hour fire wall thus to create eight two-family residences, is the occupancy classification R2 or R3.

Should I be considering the overall building 34,000 S.F / 3 Stories located on a single parcel with 10 total buildings, a clubhouse with a leasing office / 1 owner and all units are rentals or because of the 20hour party wall is this overall project two family dwellings.... I feel like this could be an IBC loop-hole but my option is these are apartment buildings.

Strictly considering the IBC and not considering NFPA 101, IMHO it's designer's choice. If the overall building/structure is all on one parcel, there's nothing that tells a designer that they must install firewalls. If the overall building area exceeds what the code allows for the occupancy classification and construction type, the designer may choose to insert one (or more) firewalls to break up the overall structure into "buildings" that are each small enough to fall within the allowable limitations.

If the occupancy classification is R-3, per IBC Table 506.2 the allowable area is unlimited. However, if it's R-2, with 3 stories in type V-B construction the maximum allowable area is 21,000 square feet (subject to potential increases for excess open perimeter) -- so, without an increase in allowable area for open perimeter, if it's classified as R-2 a 34,000 sf building doesn't meet code.

And this is exactly the type of scenario in which designers use firewalls to break an overall structure down into small "buildings" -- to bring the area of each portion of the overall structure within allowable area limits.

Just looking at the IBC, I don't see any problem. If the 16 dwelling units are split up by firewalls into eight contiguous duplexes separated by firewalls, you look at each "building" individually. 34,000 / 8 = 4,250. That's well below the allowable 21,000 sf for R-2, so IMHO if they want to call it R-3 it doesn't appear to raise any red flags that would say they can't classify it as R-3.

* * * * *

However, then we get back to NFPA 101. I don't think NFPA 101 contemplates using firewalls to break a structure into a number of smaller "buildings" for purposes of satisfying allowable area requirements.