When Has SFRM Failed?; Acoustically Sealing an Angle

Donald E. Smith, CCS

January 2007

I have a question concerning the requirements of Technical Manual 12-A: Standard Practice for the Testing and Inspection of Field Applied Sprayed Fire-Resistive Materials and the installation of sprayed-on fireproofing. Where in TM 12-A does it set forth the requirements to use to determine when an installation fails? I am specifically interested in the edges of flanges of beams.

Technical Manual 12-A sets forth the requirements for the testing procedure to be followed for the installation of sprayed applied fireproofing material. The results are based on readings taken on a pre-determined schedule depending on the size of the project. The readings are an average of the number of readings taken. If the readings are below the accepted average, then a failure has occurred.

But the edges of beams are different and are governed by paragraph 5.3.4.3, Test for Beams, Joists, Trusses and Columns. It says in part, "Certain UL and ULC fire-resistive-rating design criteria for beams and columns allow for a reduced thickness of SFRM on flange tips when a greater thickness of SFRM is applied to the contour of the beam, truss, or column. These reduced flange tip thicknesses shall be averaged apart from other sections of the beam, truss or column. Where a single thickness is required, the result shall be recorded as a single average measurement.”

The determination of a failure is established by the results of testing and is based on your knowledge and experience as an inspector. However, when you rely on your expertise and knowledge, you must be willing to present your findings in a clear and unbiased manner. You need to make the applicator aware of the basis for your subjective findings in determining the reason you have found a failure in the application. Corrective measures are contained in TM 12-A.

We have a project where the architect wants us to install sealant behind the wall angle for a lay-in acoustical tile ceiling installation. Specifically they want the sealant to be placed on the angle prior to placing the angle on the wall. Are there any industry standards governing the installation of sealant behind the wall angle? After looking through several documents and standards on lay-in acoustical tile ceiling, I cannot locate any requirements for the installation of sealant behind the wall angle. The standards covered ASTM Standards as well as standards from Ceilings & Interior Systems Construction Association.

I can only imagine why the architect would want the sealant in this particular location. Looking at the reasons why a sealant would be installed in this location, we can discount sound transmission requirements. If the architect wants it on the back of the angle it will not serve to conceal the gap between the wall angle and the wall surface. This leaves only one other purpose for the sealant in this location: to stop the infiltration of dust from the plenum space above the ceiling to the finished space below.

When you consider the difficulty in placing the sealant on the back of the wall angle or on the wall surface prior to placing the wall angle, it does not make a great deal of sense to introduce the sealant to this specific location just for the purpose of stopping potential dust from getting into the space below. The same result can be obtained by placing the sealant on top of the vertical leg on the wall angle after the angle has been installed. This is a much cleaner and faster installation and one that can be verified after the work has been completed. I am not sure how you can verify the sealant has been placed behind the wall angle after the wall angle has been installed.

Since we have moved into a new year as well as moving into a new office space I need to take a few lines to thank all of those dedicated readers who read this column each month. You have no idea how it helps the flow of words knowing that there are folks who actually read what I write each month. From my office to yours I wish you and yours a great and prosperous new year and look forward to the challenge of keeping your interest for another 12 months.

About the Author
Donald E. Smith, CCS, is AWCI’s director of technical services.