# Residential occupancy separation



## beach (May 19, 2011)

I'm using the 2010 Calif. Bldg. code based on the IBC.......

Table 508.4 shows no occupancy separation is required between an R-3 and another R-3 in, for example a duplex.

Section 508.2.4 states in exception #3 "Group R-1, R-2, R-2.1 and R-3 dwelling units and sleeping units shall be separated from other dwelling or sleeping units and from accessory occupancies contiguous to them in accordance with the requirements of Section 420.

Section 420.1 Occupancies in Groups R-1, R-2, R-2.1 and R-3, R-3.1 and R-4 shall comply with the provisions of this section and other applicable provisions of this code.

Section 420.2 Separation walls. Walls separating dwelling units in the same building, walls separating sleeping units in the same building and walls separating dwelling and sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 709.

Section 709.1 General. The following wall assemblies shall comply with this section.

1. Walls separating dwelling units in the same building as required by Section 420.2

2. Walls separating sleeping units in the same building as required by Section 420.2

The question is: Is table 508.4 a mistake by stating that no occupancy separation is required? If not, what am I missing???

Does a duplex or triplex require a fire partition or not?

IMHO, it appears that a fire partition is required.....:banghd


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## brudgers (May 19, 2011)

A two family dwelling is a single R3 occupancy.

There is a required separation of the dwelling units occurs within the occupancy.

Just as an apartment building is an R2 occupancy.


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## AegisFPE (May 19, 2011)

A duplex is probably not a Mixed Use, "Where a building contains more than one occupancy (508.1);" in such case 508 would not be applicable.  If separation were required by the referenced table, 508.2.5.1 prescribes fire barrier separation.

Fire partitions are different form of separation, which is prescribed in 420 to be provided between dwelling or sleeping units.

You are correct that a fire partition, not a fire barrier, is prescribed by the IBC between dwelling or sleeping units.

If the duplex is considered separate buildings, then a fire wall or party wall per 706 could be required.


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## beach (May 19, 2011)

I understand any building with over two occupancies would be classified as an R-2 and buildings that do not contain more than two dwelling units would be an R-3..... so a duplex would simply be an R-3 with no required separation... (Ding, the light just came on!)

Now, let's say I have a triplex that I want to use as a sprinklered R-4 ambulatory Group home with eight occupants in each unit, would I be required to provide a fire wall (not fire partition) to make each unit a separate building because the definition of an R-4 states that "Residential occupancies shall include BUILDINGS arranged for occupancy as residential care/assisted living facilities include more than six ambulatory clients excluding staff?

Thanks for the info so far, this has helped a lot.

EDIT: I'm thinking even a duplex being used as an R-4 would require a fire wall too???


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