Table 601, footnote d

[Nathan Saucier]

Type IIIA construction: R2 occupancy, Steel column structure, concrete slabs over metal deck floors. storefront glass system for the exterior.

According to Table 601, under IIIA we are allowed to have a primary structure of 1 hour. Per 704.10, if the structural members are located within the exterior wall they are required to to have the fire rating for exterior bearing walls based on IIIA (2hrs).

So now I have a steel structure within a 2hr exterior wall assembly , but footnote d says that with an approved automatic sprinkler system can be substituted for 1hr fire resistance rated construction as long as the system is not otherwise required by other provisions of the code. We do not need to use the sprinkler system to expand floor area or height. But does that fact that section 903 require sprinklers in R occupancy count as "being required by other provisions of the code"?

The thinking was that if the steel structure is within the 2hr exterior assembly, and we have sprinklers that we could use the sprinklers to bring the 2hr assembly down to 1hr. Any insight?

 

[cda]

Welcome!!

Can you state what you do for a living??

 

[cda]

Which edition of IBC are you using

 

[cda]

...........
No reply

 

[Nathan Saucier]

Which edition of IBC are you using

2012

 

[cda]

There will be some replies coming

Not my field

Here is the commentary if you do not have it::


http://diberville.ms.us/home/wp-con...C-Code-And-Commentary-Volume-I_Compressed.pdf

 

[Francis Vineyard]

Cannot use the exception to reduce the fire-resistance rating of the exterior wall.

d. An approved automatic sprinkler system in accordance with Section 903.3.1.1 shall be allowed to be substituted for 1-hour fire-resistance-rated construction, provided such system is not otherwise required by other provisions of the code or used for an allowable area increase in accordance with Section 506.3 or an allowable height increase in accordance with Section 504.2. The 1-hour substitution for the fire resistance of exterior walls shall not be permitted.

As a kind reminder 903.3.1.1 is specific to NFPA 13; 903.3.1.2 is a 13R system permitted for Group R as applicable.

 

[Nathan Saucier]

Cannot use the exception to reduce the fire-resistance rating of the exterior wall.

d. An approved automatic sprinkler system in accordance with Section 903.3.1.1 shall be allowed to be substituted for 1-hour fire-resistance-rated construction, provided such system is not otherwise required by other provisions of the code or used for an allowable area increase in accordance with Section 506.3 or an allowable height increase in accordance with Section 504.2. The 1-hour substitution for the fire resistance of exterior walls shall not be permitted.

As a kind reminder 903.3.1.1 is specific to NFPA 13; 903.3.1.2 is a 13R system permitted for Group R as applicable.

Ahh--I kept reading that lats bit of "d." as exterior bearing walls, not as exterior walls. This is very clear. Thanks, Francis!

 

[cda]

1

FROM the Commentary

 

[Nathan Saucier]

new thought--If I were to separate the steel structure from the exterior wall exposed and inset from the exterior wall. I can then have a 1hr exterior non-load bearing wall , and a 1hr primary structural frame, correct?

does the steel inherently have a fire resistance rating?

 

[Francis Vineyard]

new thought--If I were to separate the steel structure from the exterior wall exposed and inset from the exterior wall. I can then have a 1hr exterior non-load bearing wall , and a 1hr primary structural frame, correct?

does the steel inherently have a fire resistance rating?

How are you getting 1 hr exterior wall?
1 hr. required for primary structural columns (T601 footnote g) except with NFPA13 as applicable.

 

[Nathan Saucier]

Haven't decided on an 1hr exterior wall assembly yet.

for a type IIIB construction and per footnote g: section 704.10, since our primary steel column structure sits inside and separate from the exterior wall, making the exterior walls non-structural. our primary structure can have a fire rating of 0 hr and four exterior walls as a rating of 1hr depending on table 601.

Open for comments and suggestions.

 

[Francis Vineyard]

Correct http://www.thebuildingcodeforum.com...-is-it-always-a-type-iii-b.14016/#post-155235

 

[RLGA]

Haven't decided on an 1hr exterior wall assembly yet.

for a type IIIB construction and per footnote g: section 704.10, since our primary steel column structure sits inside and separate from the exterior wall, making the exterior walls non-structural. our primary structure can have a fire rating of 0 hr and four exterior walls as a rating of 1hr depending on table 601.

Open for comments and suggestions.

I'm going to ask this question because I can't find anything in your previous posts that would prevent it, but why are you using Type III construction? It sounds like your building is noncombustible, so why wouldn't you use Type IIB construction?

 

[RLGA]

Just FYI for those new to the 2015 IBC, the old Footnote 'd' of Table 601 is no longer there. Sprinkler substitution of 1-hour construction no longer exists in the IBC as of the 2015 edition.