Combustible storage IBC 413 (2018)

[Sifu]

"Attic, under-floor and concealed spaces" used for combustible storage "shall be protected on the storage side as required for 1-hour fire-resistance rated construction". Is this different from a horizontal assembly? Openings are not required to be rated.

In small B occupancy coffee shop, non-sprinklered, VB, with a basement (used for storage of combustibles like cups, paper plates and napkins), does this section apply? (Is there a difference between an "under-floor space" and a full basement?) If so, if there is a furnace, with ducts running up to the space above, do those ducts require dampers? If the exhaust from the furnace and water heater run to the roof, must they be in a shaft?

712.1.6 sends me to 717.
717.1.2 sends me to 717.6
717.6 sends me to 713 unless the duct meets all of the 5 criteria
713 requires a shaft and sends me back to 717 for duct penetrations and requires dampers.

Meanwhile, the basement could be open to the floor above, and contain an open stair, or if enclosed, only require a self-closing door.

If the "as required for" clause is not a horizontal assembly do none of the applicable sections for horizontal assemblies apply? Or does the entire section not apply since it is a story, and not an "under-floor space"? Why am I not seeing the simple answer here?

 

[RLGA]

A basement is a story and not an under-floor space. The fire resistance of the floor construction is based on the construction type unless another more specific provision requires it to be rated (e.g., occupancy separation).

Openings in a nonrated floor/ceiling assembly need only comply with 717.6.3 if you only have two stories (Basement and 1st Story).

 

[steveray]

Interesting...I think I like where Sifu was going, but agree with Ron and further it by saying that attics are specifically called out as they are not a story by definition...

[BG] ATTIC. The space between the ceiling framing of the top story and the underside of the roof.

 

[Sifu]

I was pointed to the IFC by a reliable source. I only have the '09 IFC commentary at my fingertips but since the code today is the same as then it is still applicable. In that commentary, it specifically calls out "crawl-spaces" which is consistent with RLGA's opinion, and my own suspicion. Still not crazy about 413 and the specific language. Not sure I would have considered it at all but the CBO advised the DP that it was applicable, which opened up this can of worms. I will artfully offer my opinion (and plan review) to install the ducts per 717.6.3 and try to stay out of why.

 

[RLGA]

The intent of this section is to address storage in areas that are rarely visited and are not easily accessed, such as crawl spaces, areas under stages and platforms, plenums, etc.

Here is what the 2018 Code and Commentary says about Section 413.2:

"The severity of a potential fire hazard increases where combustibles are located within concealed spaces and similar areas that provide limited access to manual fire fighting."​

If a typical basement with stair access is considered "limited," every story within a building must be regarded as having "limited access."

The Commentary also adds:

"The areas typically have low supervision and, therefore, there is increased potential for a fire to develop and spread undetected through the building."​

Most typical storage rooms will have "low supervision," since they are commonly used to support the main function of the building. People access them when they need to, but do not routinely perform their daily duties within the storage room.

The key here is that both characteristics must exist in order for Section 413.2 to apply: limited access and low supervision. If a storage area is difficult to access, then people tend not to enter unless they absolutely must, which leads to low supervision. On the other hand, a basement storage area may have lower than normal supervision, but it is easily accessed.

You said this area is used to store "cups, paper plates and napkins," which means employees regularly go to the basement to replenish items used in the coffee shop. It is not as if they keep an entire month's supply of those items behind the counter. I would bet they visit the basement at least once a day.