Using Prescriptive Fire Resistance (CH 7) to Design Fire-rated Assemblies

[jasonelliotburkRA]

I am an architect in Indiana. I am working on a 12,000 SF +/- type V-A church project. The owner does not want to install a sprinkler. Indiana is presently governed by the 2012 IBC with Indiana amendments. Indiana has an amendment which allows for a fire area to be up to 7,000 regardless of occupant load, so I broke the building into three wings (Fellowship, Sanctuary, and Education), which are separated by a 2-hour fire barrier to create three separate compliant Fire Areas. Although there was some push back in the beginning from State and Local plan reviewers, I have gotten them to accept that this is possible, per the amendment (because otherwise it simply is NOT).

The issue becomes finding UL or other tested assemblies to show compliance with the type V-A and fire barrier provisions, which require all structural elements to be one-hour min. or two-hour fire rated, respectively. I have several different types of assemblies:

• The exterior bearing walls are required to be one-hour fire rated due to being type V-A construction. In practice, this is typically achieved with 5/8" type X drywall on the interior (protected) side. Note: We have no property line issues, so protection from the exterior is not required.
  
  
• The roof is constructed with flat and scissor trusses, thus this also requires a one-hour fire rating from the interior.
  
  
• The church features a mezzanine level for the sound booth, so we now have to fire protect the floor framing for the mezzanine, which consist of 12" open web wood trusses.
  
  
• In the fellowship wing, we have a clear span space which will have steel columns and beams supporting the trusses, thus the steel structure needs to be one-hour fire rated.
  
  
• Two-hour fire barriers to separate the fire areas.

During plan review, the City's reviewing consultant requested UL assemblies or other compliant tested systems listed on the plans. I tried to find as many typical assemblies as I could, but frankly there are quite a few different types of vertical and horizontal assemblies in this building, and finding UL or GA tested assemblies to show compliance with the exact situation we are facing has been difficult if not impossible. Either the resources don't exist, I don't know where they are to be found, OR the assemblies haven't necessarily been tested. But having 25 years of experience in this field, I know this can be done, basically by installing one or two-layers of 5/8" type X gyp to conceal and protect the structure.

The reviewer was kind enough to explain to me that using the CH 7 prescriptive fire resistance is easier than finding UL or other tested assemblies in many cases. I basically nodded my head and said "OK, I will look into that!" But I have no idea how to use CH 7 for "building" one and two-hour fire rated assemblies that can show compliance. Does anyone know of any online resources I can access OR has anyone done this that explain how CH 7 can be used to simply show compliance with basic one and two hour fire-rated assemblies for combustible type V-A construction?

The weather is breaking and this client is going to want to start building soon. This is the last hurdle, and I really need to get this project finalized and through the plan review next week! Many thanks in advance for any insight. I love using this site to further my knowledge about the design and construction industry.

 

[RLGA]

Have you tried looking at fire walls instead of fire barriers? With each building being 7,000 sq. ft., you could use Type VB construction, which would give you over 7,000 sq. ft. of allowable area (6,000 sq. ft plus a frontage increase).

Thus, the only fire-rated assembly you would have to worry about is the fire wall, which still only requires a 2-hour rating.

 

[jasonelliotburkRA]

Have you tried looking at fire walls instead of fire barriers? With each building being 7,000 sq. ft., you could use Type VB construction, which would give you over 7,000 sq. ft. of allowable area (6,000 sq. ft plus a frontage increase).

No, but I like this as a creative solution. The ship has sailed a bit and I would rather get through the review as designed - we are actually changing the layout, but I can't do that until I get the project approved so the permit can be released. So as an amendment I could contemplate the ramifications of such a change to V-B with fire walls. Yeah, that could almost work...always enjoy trying to maneuver through the code to create the best case scenario for my clients so thank you!

 

[Yankee Chronicler]

Look at sections 721 and 722 of the IBC.

Also, Indiana doesn't appear to have adopted the IEBC, but that code includes a resource that has been available for decades, issued at various time by HUD, the NFPA, and now the ICC. It's IEBC Resource A -- GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS AND ASSEMBLIES. I have found that most building officials (not all) are willing to accept it once they realize how many reputable organizations have promulgated it over the years.

A key element of Resource A is the explanatory material, including Harmathy's Ten Rules. That's what tells us we can add the ratings of different materials in an assembly. To paraphrase from the Ten Rules, "If some of something is good, more of it is better." So you can take two completely different materials, each woth 30 minutes, layer them, and add them up to get one hour.

 

[Yankee Chronicler]

- we are actually changing the layout, but I can't do that until I get the project approved so the permit can be released.

Respectfully, as a long-time architect currently working as a code official, this statement makes no sense whatsoever. Once you make changes, you can't construct anything that's affected by the changes until you resubmit the changes for review and approval as amended construction documents. What's the point of obtaining a permit for something you don't intend to build?

Indiana replaced most of Chapter 1 of the IBC with statutes. Here's the rule addressing amended designs:

675 IAC 12-6-18 Addenda or revised design releases
Authority: IC 22-13-2-13
Affected: IC 22-15-3
Sec. 18. (a) No design changes or additions to the scope of work shall be made on a construction project subsequent to the
issuance of an applicable design release unless an addendum or revised design release is issued by the division.
(b) Such design changes shall not include increases in project height or area.
(c) An applicant for an addendum or revised design release shall submit the following to the division:
(1) On a form provided by the division, which shall be signed by the owner and design professional, if one is required for the
construction project, the following information:
(A) The name and address of the construction project.
(B) The division's project number.
(C) The scope of the work involved in the design changes or additions.
(D) By page or sheet number, the portions of the original plans and specifications being changed.
(E) Other reasonable data and information concerning compliance with the rules of the commission that the division may
require.
(2) One (1) copy of all changed plans and specifications.
(3) The fee established in 675 IAC 12-3.
(d) Requests for addenda or revised design releases shall be subject to the provisions of section 12 of this rule.
(e) Subsequent to the issuance of an addendum or revised design release, the original design release remains in effect as
modified by the addendum or revision design release. (Fire Prevention and Building Safety Commission; 675 IAC 12-6-18; filed
Jul 17, 1987, 2:30 p.m.: 10 IR 2697, eff Aug 1, 1987 [IC 4-22-2-36 suspends the effectiveness of a rule document for 30 days after
filing with the Secretary of State. LSA Document #87-53 was filed Jul 17, 1987.]; filed Jan 30, 1998, 4:00 p.m.: 21 IR 2098; filed
Nov 20, 2000, 3:25 p.m.: 24 IR 1007; readopted filed Sep 11, 2001, 2:49 p.m.: 25 IR 530; filed Aug 30, 2006, 2:25 p.m.: 20060927-
IR-675050108FRA; readopted filed Sep 21, 2007, 9:20 a.m.: 20071010-IR-675070388RFA; readopted filed Oct 10, 2007, 9:16 a.m.:
20071031-IR-675070388RFA; readopted filed Aug 8, 2012, 8:08 a.m.: 20120905-IR-675120260RFA; readopted filed Jul 3, 2018,
2:22 p.m.: 20180801-IR-675180204RFA)