Q: I see in several spray-applied fireproofing material specifications that hand patching of damaged or defective areas must be limited to 144 square inches. Where does this requirement come from, and are there any ways around it?
A: I contacted the technical services department of one of the manufacturers, where I was immediately and without hesitation given the correct source by the tech rep—suggesting that this is not the first time the issue has come up. As it turns out, the passage with the 144-square-inch limitation is found in the UL Directory, where it has since found its way into seemingly every spec data sheet and submittal sheet available on the Internet. A careful reading of several spec data sheets suggests that the requirement has also made its way into some building code acceptance criteria, but I wasn’t feeling rich enough to spend the necessary amount to confirm that suspicion.
The directions in the many product specification sheets instruct the reader to re-spray the product to the surface for areas larger than 144 square inches; however, there are at least a couple of ways around this requirement.
The first is to run the original product through a spray machine into a bucket before hand-applying it to the damaged or exposed surface. Running the material through the machine, it was explained to me, "puffs up” the SFRM and otherwise combines the ingredients so that they resemble and perform as if they were actually spray-applied. The page out of the UL guide listing the tested SFRM products includes which of those products this treatment applies to, so you probably need to check first with either the manufacturer or the UL listing to ensure that the product you’re considering may be used this way for patching.
The second is a specific patching material designed to be hand-applied. The SFRM manufacturers do offer patching materials for hand application, but a cursory look at the product information on them hints that they are also limited to the 144 square inches in their wet states. Before I proceed, let me state that I am absolutely not in the habit of giving product endorsements or plugs, and that I am not certified or otherwise qualified to test or recommend any product of any kind, but I happen personally know a man named Tim Vellrath who is the producer of a patching product for SFRM that advertises that it can be hand-applied to areas of up to 432 square inches in size. FYI: I worked with Tim on AWCI's Fire Safety Task Group and the Alliance for Fire and Smoke Containment and Control in the early 2000s in an effort to prevent sprinkler tradeoffs in the then emerging International Building Code to completely eliminate passive fire and smoke protection. Tim has since won AWCI's Excellence in Construction Innovation Award for the development of the above mentioned product. An internet search using his name will bring up the information on his product. If there are other such products, I am unaware of them.
Q: While discussing load-bearing cold formed steel framing assemblies, the "L-shaped header” was mentioned. What is this assembly?
A: During the development of AWCI’s soon-to-be-finalized Cold Formed Steel Framing Primer, this configuration did come up, thanks to SFIA executive director Larry Williams. Williams explains, "The L-shaped header, which until recently was only occasionally used, has begun to be used more commonly. As the name suggests, the main component of an L-shape header is a piece of cold formed steel angle with one short leg lapping over the top track of the wall and one leg extending down the side of the wall above a window or door openings. Each angle is fastened to the top track above an opening with minimum #8 screws spaced at 12 inches on center. Also, the L angle can be placed on both sides of the wall opening to form a double angle L-shape header (double L-header).”
Lee G. Jones is AWCI’s technical director. Send your questions to email@example.com.