Speaking in Code – Sprayed Fire Resistant Materials…A Heated Discussion

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Sprayed fire-resistant material (SFRM), often referred to as “spray-applied fireproofing”, is a passive fire protection material intended for direct application to structural building members. They are predominantly cementitious or mineral-fiber-based, with the fire-resistive qualities and physical characteristics varying widely between the respective types.

Project fire protection specifications may often be vague and inadequate but the International Building Code (IBC) is not. In most jurisdictions throughout the United States, the IBC code represents the MINIMUM building code requirements and is the law of the land.

IBC Chapter 17 requires special inspections for SFRM applied to floor, roof and wall assemblies and structural members. The special inspections and tests set forth by IBC must be based on inspections, tests and samples from specific floor, roof, wall assemblies and structural members. Some of the special inspections mandated in Chapter 17 of IBC in order to observe code compliance and fire-resistance rating are:

  1. Condition of substrates
  2. Thickness of application
  3. Density
  4. Bond strength adhesion/cohesion
  5. Condition of finished application after complete drying and curing.

SFRM on Structural Steel Beams in the Field

The final inspection set forth in item 5 is to make certain that the SFRM does not exhibit cracks, voids, spalls, delamination or any exposure of the substrate. The test methodology for SFRM thickness testing, bond strength, density, etc. is stipulated by IBC as ASTM E 605, “Thickness and Density of SFRM” and ASTM E 736, “Cohesion and Adhesion of SFRM”. It is important to note that while ASTM E 605 requires certain frequency of these tests, IBC requires that the tests be done more frequently than ASTM E 605 and the IBC criteria trumps the ASTM criteria. The SFRM sampling and testing frequency should be done in accordance with IBC criteria. ASTM E 605 and ASTM E 736 are IBC reference documents (listed in Chapter 35 of the IBC Code). When a standard is incorporated into the code as a reference standard, it becomes an enforceable part of the code. When a jurisdiction or state adopts the IBC code as its minimum building requirements, it adopts all of the reference standards as well. All of the testing and inspection requirements required on SFRM by Chapter 17 of IBC and the reference standard requirements (ASTM E 605 and E 736) become minimum special inspection requirements of the CODE.

SFRM Thickness Gauge

 

What Type of Fire Protection System Must Be Selected?

The Underwriters Laboratory (UL) publishes a fire resistance directory that lists various fire rated assemblies, beams, columns, walls, etc. that they have tested. Empirical data developed from many full-scale fire tests are the basis of equations that can be used to adjust the SFRM thickness for beam assemblies, columns and these equations and data are included in the commentary of the UL Fire Resistance Directory. The UL designs, generally, dictate the SFRM thicknesses and densities required during construction of new project work.

Let’s jump back to the IBC code for a moment, shall we? IBC lists three physical properties for SFRM and they are:

  1. Thickness of application
  2. Density in pounds per cubic foot
  3. Bond strength (adhesion/cohesion)

Of these three properties, only bond strength has requirements specifically outlined by the CODE. In the case of application thickness and density, the CODE states that these properties must meet the requirements of the approved (UL) fire resistance design. These properties require special inspection as required in the IBC Chapter 17. The CODE requires that one thickness test be performed for every 1,000 square feet of rated floor or roof assembly, and for 25% of the individually rated beams and columns. Previously, one test for every 10,000 square feet was acceptable. One thickness test consists of averaging several thickness measurements taken on a prescribed pattern and results in a lot of testing.

SFRM Bond Strength – Adhesion/Cohesion

In the 2009 IBC code cycle, the bond strength requirements of SFRM changed dramatically in response to The recommendations made by various investigative committees studying the 9/11 World Trade Center disaster. Before 2009, the IBC code required that the bond strength of  SFRM (when tested in accordance with ASTM E 736) be in excess of 150 psf. The IBC 2009 code cycle had code requirements move away from a single value (150 psf) for all buildings and implemented new minimum bond strength values based on the building’s height.

From IBC Chapter 4 “High-Rise Buildings”

This bond strength criteria adopted by the CODE in the IBC 2009 code cycle has no impact on any other physical property criteria for the SFRM in a specification. For example, the new code verbiage has no impact on density requirements. The selection of density criteria by the designer is an independent decision to the required minimum bond strength as dictated by the changes set forth in the 2009 IBC code.

Recent IBC code cycles since the investigations of the 9/11 disaster have resulted in a more intense special inspection process of SFRM particularly in the inspection of the substrate prior to the application of the SFRM as well as the inspections of the finished application of the SFRM after drying and curing. Ambient temperatures during the SFRM process get a lot more attention during special inspections than it (perhaps) used to. Most manufacturer’s recommendations require a minimum substrate and ambient temperature of 40 degrees F prior to, during and 24 hours after SFRM application. The temperatures at which SFRM is installed and cured are critical to the long-term fire and physical performance characteristics.

Following is a capsule summary of the most significant changes resulting from the 9/11 investigations related to SFRM and other fire protection systems.

SFRM Specific Changes

  • Increased bond strength – threefold increase in buildings 75 to 420 feet high, seven times higher bond strength required in buildings more than 420 feet in height.
  • Cleaning of substrates to avoid conditions that would prevent adhesion.
  • No cracks, voids, or spalls in finished coating.
  • Field testing to verify bond strength in maintained.
  • Special field inspections to verify thicknesses and bonds.

Other Notable Changes

  • Increased fire ratings of structural components.
  • Explicit adoption of the structural frame approach to fire resistance that requires higher rating of columns.
  • Extra (3rd) stairs and/or multiple stairs to allow better egress.
  • Photoluminescent markings on exit stairs.
  • Additional (3rd) exit stairway for buildings over 420 feet in height.
  • Increase of 50% in exit stairway widths in new sprinklered buildings.
  • Minimum of one fire access service elevator for buildings more than 120 feet high.
  • One hour increase in fire-resistance rating of structural components and assemblies in buildings over 420 feet.
  • A broadening of the definition of the primary structural frame to include bracing members essential to vertical stability (such as floor systems or cross bracing) whether or not they carry gravity loads.

We’re Just Getting Warmed Up!
For a complete picture of SFRM and how it relates to Special Inspections, F&R would love to provide an AIA accredited Lunch & Learn presentation to the professionals at your firm.  Contact Alan Tuck for more details at: atuck@fandr.com