nonseparated occupancies -IBC

We are designing a building with nonseparated occupancies. If the building is less than 75' , yet 4 stories (we meet Table 503) do we still have to comply with high rise requirements (Section 403)? My partner thinks so because of the language "most restirctive applicable provisions of Section 403" in 508.3.2.1. I think none of 403 is "applicable". Who's right?
Original Post
You would apply the provisions of High-Rise building only if it is applicable!

For Section 403.1 "High-Rise Buildings" to be applicable, an occupied floor would have to be located more than 75 feet above the lowest level of fire department vehicle access. Your building does not appear to meet that definition.

I'm assuming here that your building is located on a flat site. For buildings on a sloped site and where the lowest level of fire department vehicle access is more than 75 feet to an occupied floor level, high-rise building provisions will apply.

Therefore, I would say that provisions of high-rise buildings would not apply in your case!
This is huge! Is this true??

I am in California working on a public school project that goes through DSA (Division of the State Architect)who interpret code through our State Fire Marshall (SFM).
We are trying to utilize this concept in a Cafeteria / Multi-use Addition/Renovation project.
The plan reviewer there contacted our SFM and they are interpreting the 403 reference to apply to all conditions, effectively rendering this concept useless (in CA anyway). The CBC version of the IBC does not revise the 508.3.2 language but they are currently interpreting the 403 reference to mean that all of teh life saftey systems for a high-rise need to be included in order to use the non-separated concept. In most cases I would guess that this would be cost prohibitive.

I have an ICC interpretation manual that is really not clear on this. Is there a definite ICC interpretation out there that clarifies the 403 high rise reference?

For us UBC vets (designers anyway)this non-separated occupancy concept is so different and refreshing that it almost seems too good to be true.

Help! This would save our school district a ton and me a lot of time as I have a kitchen/multi-purpose separation where I cannot get under the 25% opening width condition of a fire barrier wall (formerly occ. separation wall).
The reference to Section 403 states "applicable." If Section 403 is not applicable due to the 75-foot minimum height, then it doesn't apply.

What it is attempting to convey is that Section 403 has some requirements that vary based on the type of occupancy. Therefore, if a highrise building is permitted to be nonseparated, regardless of what the occupancy is, the most restrictive requirements of Section 403 will apply.
In addition to the accurate information rlga-AZ provided above, Section 403 of the 2006 IBC defines a high-rise building as one having floors used for human occupancy located more than 75 feet above the lowest level of fire department vehicle access. This section defines the high-rise building and, furthermore, defines those types of buildings and structures to which the provisions for high-rise buildings do not apply.

In comparison, the 2007 CBC, Section 202 defines "High-Rise Buildings" as...

HIGH-RISE BUILDING. [SFM] As used in this code:
1. "Existing high-rise structure" means a high-rise structure, the construction of which is commenced or completed prior to July 1, 1974.
2. "High-rise structure" means every building of any type of construction or occupancy having floors used for human occupancy located more than 75 feet above the lowest floor level having building access (see Section 403.1.2), except buildings used as hospitals as defined in Health and Safety Code Section 1250.
3. "New high-rise structure" means a high-rise structure, the construction of which is commenced on or after July 1, 1974.

In addition, Section 403.1 of the CBC, provides additional information in regards to determining High-Rise buildings beyond the IBC model code language...

[SFM] For the purpose of this section (Section 403.1, Applicability), in determining the level from which the highest occupied floor is to be measured, the enforcing agency should exercise reasonable judgment, including consideration of overall accessibility to the building by fire department personnel and vehicular equipment. When a building is located on sloping terrain and there is building access on more than one level, the enforcing agency may select the level that provides the most logical and adequate fire department access.

"New building" shall mean a high-rise structure, the construction of which is commenced on or after July 1, 1974. For the purpose of this section, construction shall be deemed to have commenced when plans and specifications are more than 50 percent complete and have been presented to the local jurisdiction prior to July 1, 1974. Unless all provisions of this section have been met, the construction of such buildings shall commence on or before January 1, 1976.

For the purposes of this section, "building access" shall mean an exterior door opening conforming to all of the following:
1. Suitable and available for fire department use.
2. Located not more than 2 feet (610 mm) above the adjacent ground level.
3. Leading to a space, room or area having foot traffic communication capabilities with the remainder of the building.
4. Designed to permit penetration through the use of fire department forcible-entry tools and equipment unless other approved arrangements have been made with the fire authority having jurisdiction.

ONE MORE THING.....Typically when utilizing the concept of "nonseparated occupancies" (Section 508.3.2), no occupancy separation is required between the different occupancies (Section 508.3.2.3).

BUT in California the exception to Section 508.3.2.2 is modified to read:

508.3.2.3 Separation.
No separation is required between occupancies.
Exception: Group H-2, H-3, H-4, H-5, I-2, I-2.1 or I-3 occupancies shall be separated from all other occupancies in accordance with Section 508.3.3.

So for the occupancies listed in the exception, occupancy separation IS required and nonseparated occupancies analysis would not apply in this case.

For a school project, E occupancy, the nonseparated occupancies method is applicable and does not fall under the exception.

I don't see why provisions of Section 403 (High Rise Buildings)would apply when analyzing the building as nonseparated occupancies under provisions of Section 508.3.2. IF your project does not meet High-Rise Building definition, Section 403 is NOT applicable and you can certainly apply Section 508.3.2 to your project.

Unless SFM/DSA knows of something that is beyond the CBC in this regard, I would make sure you revisit with the plan examiner and provide him/her with your research.
We won out with the interpretation at DSA/SFM.
After researching 508.3.2 they conceded that yes 409 is only applicable in a high rise condition (which in this case we were not close to).

So, thanks to this concept in the CBC/IBC, we are able to leave our kitchen - Multi-Purpose wall as designed. And I actually had a weekend this week!

Thanks again rlga_AZ and codeyman for your help.

Regarding CBC_Newbie's comment relating to the high-rise height amendment to my knowledge CA DSA/SFM does not have one.
IBC Code Commentary: "The principle behind nonseparated use concept is that the different occupancies within the same building do not have to be separated by fire-resistance-rated assembilies if the building complies throughout with the more restrictive code requirements for high-rise buildings" Page 5-30 This is taken directly verbatum from "the book" and is not changed in California's code.

I would be very carful if I were designing a school and would request a formal in-writing determination that could be considered legal.

How can it be more clearly stated? If you use type IA construction and sprinkler through-out no separations are required. Well Duh! If everything is fire-resistive then it already is separated with rated corridors etc.
Mark Morton
Plans Examiner
City of Upland, CA
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