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1 HR Separation

DJMenitoff

Registered User
Joined
Oct 12, 2020
Messages
21
Location
Michigan
I am designing a 1 story addition to a "M" mercantile store. The addition will have two components. One is a storage area connected to the existing store and the other is a single family dwelling unit. The code official here has stated that the commercial portion will fall under Michigan Building Code (IBC 20015) and the residential portion will be reviewed under IBC Residential code. My question: There will be a 1hr rated wall that divides the spaces. The dividing wall will continue to the underside of the roof deck (drywall around joists). Can the roof joists be continuous and span both spaces or does the dividing wall have to be a bearing wall and each roof sit on its own wall? meaning essentially building two load bearing walls each that supports the roof structure for the two different spaces?

 
We really need some more info before that question can be answered.

Is the 1-hr a separation wall for mixed occupancies per Table 508.4 (would indicate NFPA 13 system is in place)?
Is it a fire barrier to reduce the fire area? If so, Table 707.3.10 would require the fire barrier to be 2-hr rated.
It is a fire wall to create separate buildings? If so Table 706.4 would require the fire wall to be 3-hr rated.

Have you reviewed the provisions for mixed-use? Do you want to go mixed-use non-separated or separated? What are the areas of each use and the building in entirety?

What type of sprinkler system do you want to install? NFPA 13R or full NFPA 13?
 
IBC 2018
One-hour fire partition is the minimum required. Use a one hour rated roof/ceiling assembly and you should be good unless there are local/state amendments that say otherwise.

508.3.3 Separation.
No separation is required between nonseparated occupancies.

Exceptions:

1. Group H-2, H-3, H-4 and H-5 occupancies shall be separated from all other occupancies in accordance with Section 508.4.

2. Group I-1, R-1, R-2 and R-3 dwelling units and sleeping units shall be separated from other dwelling or sleeping units and from other occupancies contiguous to them in accordance with the requirements of Section 420.

420.2 Separation walls.
Walls separating dwelling units in the same building, walls separating sleeping units in the same building and walls separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 708.

708.1 General.
The following wall assemblies shall comply with this section.

1. Separation walls as required by Section 420.2 for Group I-1 and Group R occupancies.

708.3 Fire-resistance rating.
Fire partitions shall have a fire-resistance rating of not less than 1 hour.

708.4 Continuity.
Fire partitions shall extend from the top of the foundation or floor/ceiling assembly below and be securely attached to one of the following:

1. The underside of the floor or roof sheathing, deck or slab above.

2. The underside of a floor/ceiling or roof/ceiling assembly having a fire-resistance rating that is not less than the fire-resistance rating of the fire partition.
 
IBC 2018
One-hour fire partition is the minimum required. Use a one hour rated roof/ceiling assembly and you should be good unless there are local/state amendments that say otherwise.

508.3.3 Separation.
No separation is required between nonseparated occupancies.

Exceptions:

1. Group H-2, H-3, H-4 and H-5 occupancies shall be separated from all other occupancies in accordance with Section 508.4.

2. Group I-1, R-1, R-2 and R-3 dwelling units and sleeping units shall be separated from other dwelling or sleeping units and from other occupancies contiguous to them in accordance with the requirements of Section 420.

420.2 Separation walls.
Walls separating dwelling units in the same building, walls separating sleeping units in the same building and walls separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 708.

708.1 General.
The following wall assemblies shall comply with this section.

1. Separation walls as required by Section 420.2 for Group I-1 and Group R occupancies.

708.3 Fire-resistance rating.
Fire partitions shall have a fire-resistance rating of not less than 1 hour.

708.4 Continuity.
Fire partitions shall extend from the top of the foundation or floor/ceiling assembly below and be securely attached to one of the following:

1. The underside of the floor or roof sheathing, deck or slab above.

2. The underside of a floor/ceiling or roof/ceiling assembly having a fire-resistance rating that is not less than the fire-resistance rating of the fire partition.
This path only works if they can go with mixed-use non-separated. Otherwise, the separation requirements will be much more than a 1-hr partition.
 
We really need some more info before that question can be answered.

Is the 1-hr a separation wall for mixed occupancies per Table 508.4 (would indicate NFPA 13 system is in place)?
Is it a fire barrier to reduce the fire area? If so, Table 707.3.10 would require the fire barrier to be 2-hr rated.
It is a fire wall to create separate buildings? If so Table 706.4 would require the fire wall to be 3-hr rated.

Have you reviewed the provisions for mixed-use? Do you want to go mixed-use non-separated or separated? What are the areas of each use and the building in entirety?

What type of sprinkler system do you want to install? NFPA 13R or full NFPA 13?
This path only works if they can go with mixed-use non-separated. Otherwise, the separation requirements will be much more than a 1-hr partition.
This is where I'm having trouble determining if I can go with mixed-use non-separated.
No sprinkler.
The square footages are: Existing M= 1,063sf + Addition of 286sf storage. New DU addition is ~600sf.
 
This is where I'm having trouble determining if I can go with mixed-use non-separated.
No sprinkler.
The square footages are: Existing M= 1,063sf + Addition of 286sf storage. New DU addition is ~600sf.
Ummm.... hate to tell you, but you are going to sprinkle at least the residential portion of the building.

[F] 903.2.8 Group R
An automatic sprinkler system installed in accordance with Section 903.3 shall be provided throughout all buildings with a Group R fire area.

[F] 903.2.8.1 Group R-3
An automatic sprinkler system installed in accordance with Section 903.3.1.3 shall be permitted in Group R-3 occupancies.


Given the square footages that you noted, it is only about 2,000sf, so you should be just fine with mixed-use non-separated. But with no separation, the AHJ will most likely (and should per the IBC), have you install a full NFPA 13 system in the entire building.

However, what I would suggest, especially given the size of the building, is that you go for a Live/Work Unit per IBC Section 419.

419.1 General
A live/work unit shall comply with Sections 419.1 through 419.9.
Exception: Dwelling or sleeping units that include an office that is less than 10 percent of the area of the dwelling unit are permitted to be classified as dwelling units with accessory occupancies in accordance with Section 508.2.

419.1.1 Limitations
The following shall apply to all live/work areas:

  1. The live/work unit is permitted to be not greater than 3,000 square feet (279 m2) in area;
  2. The nonresidential area is permitted to be not more than 50 percent of the area of each live/work unit;
  3. The nonresidential area function shall be limited to the first or main floor only of the live/work unit; and
  4. Not more than five nonresidential workers or employees are allowed to occupy the nonresidential area at any one time.
You will still end up doing fire sprinklers though...

419.5 Fire Protection
The live/work unit shall be provided with a monitored fire alarm system where required by Section 907.2.9 and an automatic sprinkler system in accordance with Section 903.2.8.
 
Ummm.... hate to tell you, but you are going to sprinkle at least the residential portion of the building.

[F] 903.2.8 Group R
An automatic sprinkler system installed in accordance with Section 903.3 shall be provided throughout all buildings with a Group R fire area.

[F] 903.2.8.1 Group R-3
An automatic sprinkler system installed in accordance with Section 903.3.1.3 shall be permitted in Group R-3 occupancies.


Given the square footages that you noted, it is only about 2,000sf, so you should be just fine with mixed-use non-separated. But with no separation, the AHJ will most likely (and should per the IBC), have you install a full NFPA 13 system in the entire building.

However, what I would suggest, especially given the size of the building, is that you go for a Live/Work Unit per IBC Section 419.

419.1 General
A live/work unit shall comply with Sections 419.1 through 419.9.
Exception: Dwelling or sleeping units that include an office that is less than 10 percent of the area of the dwelling unit are permitted to be classified as dwelling units with accessory occupancies in accordance with Section 508.2.

419.1.1 Limitations
The following shall apply to all live/work areas:

  1. The live/work unit is permitted to be not greater than 3,000 square feet (279 m2) in area;
  2. The nonresidential area is permitted to be not more than 50 percent of the area of each live/work unit;
  3. The nonresidential area function shall be limited to the first or main floor only of the live/work unit; and
  4. Not more than five nonresidential workers or employees are allowed to occupy the nonresidential area at any one time.
You will still end up doing fire sprinklers though...

419.5 Fire Protection
The live/work unit shall be provided with a monitored fire alarm system where required by Section 907.2.9 and an automatic sprinkler system in accordance with Section 903.2.8.
Thanks classicT for all your help. I'm crying about a sprinkler for such a small space. There must be a way to avoid one. Seems like providing a 2HR separation would be enough. Banging my head.
 
Yep them pesky codes """shall be provided throughout all buildings with a Group R fire area."""""

Not sure your R setup, but have had enough people die or almost die, while sleeping at a work place.
 
This path only works if they can go with mixed-use non-separated. Otherwise, the separation requirements will be much more than a 1-hr partition.
Correct non-separated uses only. I don't have the sprinkler requirements in my jurisdiction so I forgot about that requirement.
So create a separate fire area. You will need a 2-hour fire barrier and no the trusses cannot penetrate the fire barrier. This will require you to only sprinkle the residential dwelling and not the entire building.
 
Correct non-separated uses only. I don't have the sprinkler requirements in my jurisdiction so I forgot about that requirement.
So create a separate fire area. You will need a 2-hour fire barrier and no the trusses cannot penetrate the fire barrier. This will require you to only sprinkle the residential dwelling and not the entire building.
Sprinkler shall be provided throughout the building... so with a fire barrier, you still must sprinkle both sides.

Only way out of sprinklers for the non-R use is a fire wall.
 
Until you get this handsome little tweak in 2018 IBC...Which will raise all kinds of heck....No more pass on suppression for FW....

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.
 
Last edited by a moderator:
# ~ # ~ #

What type of storage is it [ i.e. - S-1, ...S-2 or an H Occ. Group ] ?
What will actually be stored in the proposed Storage Area ?

# ~ # ~ #
 
Sprinkler shall be provided throughout the building... so with a fire barrier, you still must sprinkle both sides.
Not correct if you create two separate fire areas in this case an "M" and a "R" fire areas only the "R" fire area is required to be sprinkled

2018 IEBC
1101.1 Scope.
An addition to a building or structure shall comply with the International Codes as adopted for new construction without requiring the existing building or structure to comply with any requirements of those codes or of these provisions, except as required by this chapter. Where an addition impacts the existing building or structure, that portion shall comply with this code.


1102.3 Fire protection systems.
Existing fire areas increased by the addition shall comply with Chapter 9 of the International Building Code.
If you construct a 2-hour fire barrier you are not increasing the existing fire area therefore you are not required to sprinkle the existing fire area.
Unless you can find charging language in the IEBC telling you you must comply with Chapter 9 of the IBC then 903.2.8 is not applicable

[F] 903.2 Where required.
Approved automatic sprinkler systems in new buildings and structures shall be provided in the locations described in Sections 903.2.1 through 903.2.12.
 
1102.3 Fire protection systems.
Existing fire areas increased by the addition shall comply with Chapter 9 of the International Building Code.
[F] 903.2 Where required.
Approved automatic sprinkler systems in new buildings and structures shall be provided in the locations described in Sections 903.2.1 through 903.2.12.
Ok, so IEBC 1102.3 says that you have to comply with Ch. 9 of the IBC. IBC 903.2 does identify new buildings and structures, but that is because that is the intent of the IBC. The IEBC is the applicable code, which in turn references the IBC.

We differ in our opinion of what that means, but to me, that means that the addition (per IEBC) must comply with fire sprinklers as if it were new construction (per IBC) and have sprinklers throughout the building.
 
# ~ # ~ #

What type of storage is it [ i.e. - S-1, ...S-2 or an H Occ. Group ] ?
What will actually be stored in the proposed Storage Area ?


# ~ # ~ #
Maybe it shouldn't be classified as storage. It's a small retail store that sells a variety of items and this would be their stockroom, Perhaps it should just be classified as M-1 309.1 Mercantile Group M "Mercantile Group M occupancy includes, among others, the use of a building or structure or a portion thereof for the display and sale of merchandise, and involves stocks of goods, wares or merchandise incidental to such purposes and accessible to the public."

Maybe it should be labeled a Stockroom
 
Maybe it shouldn't be classified as storage. It's a small retail store that sells a variety of items and this would be their stockroom, Perhaps it should just be classified as M-1 309.1 Mercantile Group M "Mercantile Group M occupancy includes, among others, the use of a building or structure or a portion thereof for the display and sale of merchandise, and involves stocks of goods, wares or merchandise incidental to such purposes and accessible to the public."

Maybe it should be labeled a Stockroom
Potential just an accessory use to the mercantile area.
 
Yep them pesky codes """shall be provided throughout all buildings with a Group R fire area."""""

Not sure your R setup, but have had enough people die or almost die, while sleeping at a work place.
They're not sleeping at the workplace per se. They would be in a totally separate unit with a 2hr fire separation and not penetrations or ability to go from one to the other. It's not like their sleeping on a cot in the back room of the store.
 
Correct non-separated uses only. I don't have the sprinkler requirements in my jurisdiction so I forgot about that requirement.
So create a separate fire area. You will need a 2-hour fire barrier and no the trusses cannot penetrate the fire barrier. This will require you to only sprinkle the residential dwelling and not the entire building.
You interpret it that even with the 2hr separation we'll need to sprinkle the residential side?
 
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