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Why are W/D Ratios Important in IFRM Listed Designs for Structural Steel Fire Protection?

Why are W/D ratios important in IFRM listed designs for structural steel fire protection?

W/D
W = Weight (per lineal foot)
D = Heated Perimeter (inches)

Building Product Directories from accredited third-party laboratories such as Intertek & Underwriters Laboratories publish FULL SCALE listed designs that meet IBC (International Building Code) fire resistance requirements for IFRM manufactures. W/D ratios are specific to individual structural steel members within these design listings to determine the required final DFT (dry film thickness) of IFRM that must be applied to achieve the hourly rating.

Listed designs found in these directories provide the minimum column or beam sizes that have been tested by the manufacturer. For example, the minimum wide flange column size in Contego International’s design CII/IF 120-02 has a W/D ratio of 0.29 for up to a 2-hour fire resistance rating. This makes Contego International the only IFRM manufacture on the market today able to safely protect the smallest wide flange columns for up to 2-hours while doing so with up to 20% less IFRM product keeping your project on time at a lower cost per square foot.

IFRM W/D Ratios 101:

+ IFRM applied to meet equal or greater W/D ratios of a steel member of the same configuration tested to full scale hourly ratings is acceptable.

– IFRM applied using a thickness or extrapolation of a larger steel member to cover a smaller steel member that has a lower W/D ratio than listed is not acceptable.

At Contego International LIFE SAFTEY is our highest priority. Before using an IFRM on your project, investigate the manufactures published design listings to ensure testing has been done to FULL SCALE and the W/D ratios of the steel members have been tested to the specific hourly rating requirements.

ICC-ESR 5314 UPDATED DESIGNS

ESR-5314

Contego International has updated our ESR 5314 for (HS) High Solids and Original Formula Intumescent RFB coatings:

2021, 2018, 2015 International Building Code

  • IBC – Building
  • IRC – Residential
  • IFC – Fire

2023 Florida Building Code

  • FBC – Building
  • FRC – Residential

2022 California Building Code

  • CBC – Building
  • CRC – Residential
  • CFC – Fire

2023 Los Angeles Building Code

  • LABC – Building
  • LARC – Residential
  • LAFC – Fire

If you would like to receive a copy of the ESR #5314 report please email aaron@contegointernational.com.

Contego High Solids RFB IFRM – Wide Flange Column Design CII/IF 120-02 Intumescent Fire Protection

Contego IFRM coatings continue to lead the Intumescent Fireproofing Industry, pushing the standards higher with each test result.  Contego HS RFB Intumescent coating was tested April of 2024 at Intertek Laboratories in Elmendorf, TX achieving a new CII/IF 120-02 listed design.

Contego High Solids RFB is one of two water-based IFRM Manufacturers that can provide 2-hour fire resistance ratings on a W8X10 column with a listed design.

Design No. CII/IF 120-02 encompasses the following structural steel:

SOLID STRUCTURAL STEEL COLUMN: Use solid steel sections, I-shape or W-shape, having nominal Hp/A or W/D section factors based on four-sided exposure. Refer to Table CII/IF 120-02 for specific Hp/A or W/D section factors.

Save Time and Project Cost!

With 85 Hp/A listed data points, Contego’s design will cover your structural steel Wide Flange Column needs with 30-40% less product and labor requirements depending on column size and manufacture used. The chart below compares DFT (dry film thickness) coating requirements for a 1-hour and 2-hour fire resistance rating on wide flange columns with the leading intumescent manufactures listed designs in the USA currently.