# IBC 2009 fire-separation question



## inspecterbake (Oct 8, 2014)

82K+ sq. ft. unseparated mixed use (A-2, R-1,B, S-2). Two stories, Type IIIB construction, sprinklered per IBC 903.3.1.1.

Is a fire-rated horizontal barrier required between Floor 1 A-2 and Floor 2 R-1 sleeping rooms?


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## Builder Bob (Oct 8, 2014)

Yes, 420.3 Horizontal separation. Floor assemblies separating dwelling units in the same buildings, floor assemblies separating sleeping units in the same building and floor assemblies separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as horizontal assemblies in accordance with Section 712.


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## north star (Oct 8, 2014)

*( = )*

Also, ...see Table 508.4, in the `09 IBC.



*( = )*


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## cda (Oct 8, 2014)

You know just because it has the word "fire" does not mean it is in the fire code.

Hence, my push to rename the international fire code to the international incendio

 code, so there will not be a misunderstanding.

And it sounds more international


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## steveray (Oct 8, 2014)

Agree with BB....(I believe) without looking, you always separate the dwelling/sleeping units.....More specific vs. the broader mixed use non-separated...

712.3 Fire-resistance rating. The fire-resistance rating of floor and roof assemblies shall not be less than that required by the building type of construction. Where the floor assembly separates mixed occupancies, the assembly shall have a fire-resistance rating of not less than that required by Section 508.4 based on the occupancies being separated. Where the floor assembly separates a single occupancy into different fire areas, the assembly shall have a fire-resistance rating of not less than that required by Section 707.3.9. Horizontal assemblies separating dwelling units in the same building and horizontal assemblies separating sleeping units in the same building shall be a minimum of 1-hour fire-resistance-rated construction.

Exception: Dwelling unit and sleeping unit separations in buildings of Type IIB, IIIB and VB construction shall have fire-resistance ratings of not less than 1/2 hour in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.


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## inspecterbake (Oct 8, 2014)

It should be noted there is no reference to IBC §508.4 in the exception above, nor is there a reference to IBC CODE ANALYSIS

As indicated, the building has been designed as a non-separated mixed-use structure complying with IBC §508.3. Per IBC §508.3.3:

No separation is required between non-separated occupancies.

Exception 1 is not applicable since there is no Group H (High Hazard) occupancy in the building.

Exception 2: Group I-1, R-1, R-2 and R-3 dwelling units and sleeping units shall be separated from other dwelling units or sleeping units and from other occupancies contigu§508.4 in IBC §420. IBC §420 requires vertical and horizontal fire-resistive separation of Group I-1, R-1, R-2 and R-3 dwelling units and sleeping units from other dwelling units or sleeping and other adjacent occupancies regardless of whether the building follows a separated or non-separated mixed-use. Had the building been required to comply as a separated mixed-use building in order to meet height and area requirements, than additionally, the occupancy separation requirements of IBC §508.4 and Table 508.4 would be applicable and require a 1-hr fire-resistance rated horizontal assembly supported by 1-hr fire-resistance rated supporting construction for the occupancies involved in this project.

Requiring the fire-resistance rating of supporting construction in a non-separated mixed-use occupancy building of unprotected construction unfairly penalizes the building owner/designer who chooses to construct a smaller building as a consequence of not providing the additional occupancy separation in the first place. In essence, there would be no distinction (and no need for the current prescriptive code language) between non-separated mixed-use occupancies and separated mixed-use occupancies. Further, the vast majority of multi-story buildings with R-1 and R-2 occupancies also contain other occupancy types (i.e. fitness rooms, storage rooms, community rooms, etc.); so following the logic of requiring fire-resistance rating of supporting construction would prohibit the use of unprotected construction for buildings containing residential occupancies. It is quite clear that the IBC does permit residential occupancies of unprotected construction.

Koffel Associates has contacted technical staff at the ICC for their interpretation of this issue. ICC technical staff supports our interpretation that no fire-resistance rating of the supporting construction is required in a non-separated mixed-use building of unprotected construction.


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## inspecterbake (Oct 8, 2014)

Sorry doing to many things at once this morning here is the first part of the response from the designer.

CODE ANALYSIS

As indicated, the building has been designed as a non-separated mixed-use structure complying with IBC §508.3. Per IBC §508.3.3:

No separation is required between non-separated occupancies.

Exception 1 is not applicable since there is no Group H (High Hazard) occupancy in the building.

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


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## cda (Oct 8, 2014)

is this a plain old two or three story motel/ hotel, where they have a few meeting/ breakfast rooms on the first floor.

As in accessory to the use or part of a larger main occupancy.


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## steveray (Oct 8, 2014)

Inspecterbake....you are not protecting the construction, you are rating the separation.....Not sure if I understand your position....


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## inspecterbake (Oct 8, 2014)

Ok does R-1 & A-2 need to have a one hour fire separation in type IIIB construction?


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## steveray (Oct 8, 2014)

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 709.


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## mtlogcabin (Oct 8, 2014)

The supporting construction does not have to be protected when separating dwelling and sleeping units with fire partitions.

709.4

.........The supporting construction shall be protected to afford the required fire-resistance rating of the wall supported, except for walls separating tenant spaces in covered mall buildings , walls separating dwelling units , walls separating sleeping units and corridor walls in buildings of Type IIB, IIIB and VB construction.


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## Builder Bob (Oct 9, 2014)

Do not get the fire rating requirments for fire partitions and fire barriers confused. Fire Barriers require the supporting construction to be protected, a fire partition does not.


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## north star (Oct 9, 2014)

*( = )*





> "Is a fire-rated horizontal barrier required between Floor 1 A-2 and Floor 2 R-1 sleeping rooms?"


According to Section 508.3 [ in the `09 IBC ], ..."apparently not" [  stated in amazement !  ]  :-oI'm still trying to wrap my head around this one.......Some would tend to think that the

"most restrictive" application should apply, and that a fire rated assembly is normally

[ or should be ] required between any occupancy group and a Residential occupancy

above it.

I guess as long as the Height & Area limitations are met, ...it has the correct Type

of construction, and is fully sprinklered, ...it is compliant.   :shock:



*( = )*


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## steveray (Oct 9, 2014)

Still required to be separated......

508.3.2 Allowable building area and height. The allowable building area and height of the building or portion thereof shall be based on the most restrictive allowances for the occupancy groups under consideration for the type of construction of the building in accordance with Section 503.1.508.3.3 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.


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## mtlogcabin (Oct 9, 2014)

420.3 Horizontal separation.

Floor assemblies separating dwelling units in the same buildings, floor assemblies separating sleeping units in the same building and floor assemblies separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as horizontal assemblies in accordance with Section 712.

712.3 Fire-resistance rating.

The fire-resistance rating of floor and roof assemblies shall not be less than that required by the building type of construction. Where the floor assembly separates mixed occupancies, the assembly shall have a fire-resistance rating of not less than that required by Section 508.4 based on the occupancies being separated. Where the floor assembly separates a single occupancy into different fire areas , the assembly shall have a fire-resistance rating of not less than that required by Section 707.3.9. Horizontal assemblies separating dwelling units in the same building and horizontal assemblies separating sleeping units in the same building shall be a minimum of 1-hour fire-resistance-rated construction.

Exception: Dwelling unit and sleeping unit separations in buildings of Type IIB, IIIB and VB construction shall have fire-resistance ratings of not less than 1/2 hour in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

712.4 Continuity.

Assemblies shall be continuous without openings, penetrations or joints except as permitted by this section and Sections 708.2, 713.4, 714 and 1022.1. Skylights and other penetrations through a fire-resistance-rated roof deck or slab are permitted to be unprotected, provided that the structural integrity of the fire-resistance-rated roof assembly is maintained. Unprotected skylights shall not be permitted in roof assemblies required to be fire-resistance rated in accordance with Section 704.10. The supporting construction shall be protected to afford the required fire-resistance rating of the horizontal assembly supported.

Exception: In buildings of Type IIB, IIIB or VB construction, the construction supporting the horizontal assembly is not required to be fire-resistance-rated at the following:

1.    Horizontal assemblies at the separations of incidental uses as specified by Table 508.2.5, provided the required fire-resistance rating does not exceed 1 hour.

2.    Horizontal assemblies at the separations of dwelling units and sleeping units as required by Section 420.3.

3.    Horizontal assemblies at smoke barriers constructed in accordance with Section 710.

I agree the rated separation is required. I don't see where supporting construction of horizontal separation is required to be rated regardless if 1-hour or 1/2 hour rating is required


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