Fire Areas

[Markmax33]

I wanted to double check my knowledge on fire areas:

FIRE AREA. The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such areas are included within the horizontal projection of the roof or floor next above.

This does not include occupancy separations in TABLE 508.4 REQUIRED SEPARATION OF OCCUPANCIES (HOURS) correct?

Assuming that is correct, what is the correct term for the separated areas created by TABLE 508.4 REQUIRED SEPARATION OF OCCUPANCIES (HOURS) if you don't call them fire areas? I guess you call them separated group A, separated group B, etc if there were multiple occupancy types in each group?

Thanks!

 

[mtlogcabin]

TABLE 707.3.9 FIRE-RESISTANCE RATING REQUIREMENTS FOR FIRE BARRIER ASSEMBLIES OR HORIZONTAL ASSEMBLIES BETWEEN FIRE AREAS



A fire area separation usually requires a higher rating then an occupancy separation. 2 hours or greater unless a U occupancy

 

[mark handler]

http://www.specsandcodes.com/Articles/The%20Code%20Corner%20No.%2027%20-%20Fire%20Areas.pdf

 

[steveray]

You would have to look in the tables for ratings, but fire barriers can be used to determine fire areas and separation between uses....

 

[Markmax33]

View attachment 1021

Okay so the separation created by TABLE 508.4 REQUIRED SEPARATION OF OCCUPANCIES (HOURS) should be called "use areas" and the areas created by fire barriers, fire walls, etc should be "fire areas". They may overlap from time to time. Does that sound correct? I'm creating a table that lets the user change the fire areas and use areas automatically and updates all of the calculations on the fly but I need to make a sure the terms are correct. I was incorrectly using "fire areas" for everything including "use areas" so I need to add another column to my table. If anyone would like to test it out you can login here:http://codecomply3.sitedemo.mego login in the upper right hand corner. The temp login and password is user/user. There are a few videos to help guide you along.

View attachment 1021

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[RLGA]

Sorry to be late coming into this (I had a huge project that overwhelmed me and I put off any forum activity). Mark, thanks for the reference to my article. However, that article was written in 2008 before the 2009 IBC was published, which changed the requirements.

Occupancy separations and fire areas should not be confused--they are two separate things.

Occupancy separations do use fire barriers to separate different occupancy groups when and where required. Before the 2009 IBC, any fire barrier used as an occupancy separation would also define the limits of a fire area.

However, in the 2009 IBC, Section 707.3.9 (Section 707.3.10 in the 2012 IBC) was changed to state that fire barriers used to determine fire areas between different occupancies must comply with Table 707.3.9 (Table 707.3.10 in the 2012 IBC), which may have a higher hourly rating than that required for occupancy separation. For example, a nonsprinklered F-1 occupancy adjacent to an A occupancy would require a 2-hour fire barrier per Table 508.4 if the separated occupancies method is used. But if the fire is also to be used to determine the limits of a fire area, then a 3-hour fire barrier is required.

Fire areas are used primarily to determine whether or not a fire sprinkler is required. So, if you're using the separated occupancies method, and you used Table 508.4, you had better check it against the Table in Section 707--your fire area may be larger than you expected and a sprinkler system may still be required if you do not increase the rating of the fire barrier. The Table in Section 707 is still used when dividing a single occupancy group into smaller fire areas to avoid exceeding the floor area thresholds for sprinkler systems in Section 903.

 

[JBI]

A 'fire area' is a design tool. Typically used to mitigate the need for some type of fire suppression (often sprinklers).

Separated occupancies are an option that allows the 'sum of the ratios' to determine area, as opposed to non-separated occupancies that would require the more restrictive provisions for Chapter 9 to apply to the entire space. These are also 'design tools' I suppose... but creating 'fire areas' is never actually required whereas in a mixed use building (more common than not) the options are (generally) 'separated' or 'non-separated'.