Fireproofing a Steel Bow Truss Assembly

[TJKollar]

Hi Guys, So I have a project in Chicago that is requiring us to have a 1 hour fire resistance for a steel bow truss assembly below 20'-0". Currently I am having difficulties determining a ANSI/UL detail that states the required thickness of fibrous fireproofing material. The bow truss consists of steel angles and gusset plates. Sizes are undefined. I have attached a photo for reference as well. BTW, yes we are removing the combustible roof construction and infilling it will non combustible materials. Any insight or direction would be helpful.Thank You,~Tim

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[cda]

Welcome

How did you find us???

Not a fireproofer

But would it be according to the manufacture also, as far as application and thickness

 

[mtlogcabin]

In-tumescent paint?

Intumescent Paint For Steel | Intumescent Paint

 

[steveray]

Welcome!....Why is the roof required to be rated?....2A construction?

 

[TJKollar]

Here is the exact correction from the plan reviewer:

"List fire ratings with UL design number for floors, roof, exterior walls and columns. For extior walls clarify if load or nonload bearing & if inside or outside exposure [13-60-100]. WHAT IS THE MATERIAL, MINIMUM THICKNESS AND BASIS FOR SPRAY-ON FIREPROOFING."

Due to square footage restrictions we had to go with a I-C construction. Table 13-60-100 in the CBC states that all beams, girders & trusses supporting roofs are to have a 1 hour fire rating. Foot note (k) indicates that Fire protection is not required on roofs or supporting members above 20'-0'. Our roof is above 20'-0", so therefore we are only looking for 1 hour to protect the bow truss below 20'-0".

 

[TJKollar]

It wasn't hard to find you guys, I googled "Building code forum".

We need a UL design that indicates a thickness of the spray-on fire proofing as requested in our permit correction. The manufacturer's work won't cut the mustard on this one.

 

[TJKollar]

@mtlogcabin

Due to the complexity of the bow truss and height of it was suggested by the contractor to go with the spray-on.

 

[cda]

Table 601

Note b???

 

[cda]

It wasn't hard to find you guys, I googled "Building code forum".We need a UL design that indicates a thickness of the spray-on fire proofing as requested in our permit correction. The manufacturer's work won't cut the mustard on this one.

A ul design for spray on the a manufacture will supply? Seems like they should accept a listed product and application

 

[cda]

http://www.aisc.org/bookstore/itemRedirector.aspx?id=15314

http://www.icc-es.org/Reports/pdf_files/ESR-1649.pdf

There may be other icc reports

http://www.fireretardantsinc.com/50_44/images/50-44_Product.pdf

 

[Mark K]

There are three ways 1) Fire test results that are applicable, 2) proscriptive code provisions (IBC Section 722.5.2.3), or 3) an engineered design that calculates the temperature of the protected steel based on a thermal analysis.

The manufacturer may help you to find the right thickness but the manufacturer does not get to define that thickness. Similarly an ICC-ES report does not by itself satisfy the code. If an ICC-ES report was based on one of the three methods then what you want to see is the underlying report.

Similarly a UL report is useful only if it was based on the required ASTM tests.

 

[cda]

There are three ways 1) Fire test results that are applicable, 2) proscriptive code provisions (IBC Section 722.5.2.3), or 3) an engineered design that calculates the temperature of the protected steel based on a thermal analysis.The manufacturer may help you to find the right thickness but the manufacturer does not get to define that thickness. Similarly an ICC-ES report does not by itself satisfy the code. If an ICC-ES report was based on one of the three methods then what you want to see is the underlying report.

Similarly a UL report is useful only if it was based on the required ASTM tests.

Not a fire proofer just trying to learn

Is it correct the manufacture has their material tested/ listed for a specific rating and application?

So if I go to a manufacture and they can give me documentation that this meets say one hour for the steel I am applying it to, I am good to go? As long as the ahj approves the documentation ?

Seems like 704.13 says that