Exposed fasteners in metal deck

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Author Message David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 1037 Registered: 03-2002 Posted on Thursday, March 26, 2009 - 07:11 pm:    An architect asked about clipping the ends of the screw fasteners that penetrate a metal roof deck. She is concerned about puncturing and deflating balls in the gym. I told her that I believe code requires 3/4 inch minimum exposed fastener penetration through metal decks. Is there something that we can cover the fasteners with or another way to solve the problem? Wayne Yancey Senior Member Username: wayne_yancey Post Number: 178 Registered: 01-2008 Posted on Thursday, March 26, 2009 - 07:14 pm:    David, The fasteners will be in the high flutes. What kind of inflated ball with get between the flutes of metal deck. A tennis ball? John Regener, AIA, CCS, CCCA, CSI, SCIP Senior Member Username: john_regener Post Number: 434 Registered: 04-2002 Posted on Thursday, March 26, 2009 - 07:38 pm:    The screws are hardened steel. What will be used to cut them that won't go dull after a few snips? David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 1038 Registered: 03-2002 Posted on Thursday, March 26, 2009 - 08:58 pm:    Wayne, Supposedly a volleyball has a small enough diameter to fit between the flutes and get punctured. A basketball has too large a diameter to get damaged. I will measure and find out. I half jokingly recommended they stick brightly colored tennis balls on the ends of the protruding screws. ;-) Russ Hinkle, AIA, CCS Senior Member Username: rhinkle Post Number: 59 Registered: 02-2006 Posted on Friday, March 27, 2009 - 07:28 am:    I remember the same issue coming up a few years back. The architect had a fastener that flattened out (and maybe snapped off?) that was recommended. We priced it as an alternate and when all was said and done, standard methods were used. Unfortunately, I do not remember the name of the product. Jerry Tims AIA, CSI Senior Member Username: jtims Post Number: 66 Registered: 04-2005 Posted on Friday, March 27, 2009 - 08:27 am:    I could be wrong....(I was once), but I believe the 3/4" penetration is a Factory Mutual requirement. So if you're designing your roof to FM requirements, you may not have a choice but to live with it. We typically use acoustic decks (the cellular type) in gymnasiums so exposed fasteners really isn't an issue....that is until the deck gets Value-DEengineered to a less expensive non-cellular acoustic deck.....or a standard deck. On more than one occasion we've had to convince our owners that exposed fasteners are beautiful....except when it's their decision to back off of what was originally designed and specified. Then it's a simple case of WYSIWYG. George A. Everding, AIA, CSI, CCS, CCCA Senior Member Username: geverding Post Number: 467 Registered: 11-2004 Posted on Friday, March 27, 2009 - 09:54 am:    I guess I have too much Missouri "Show-Me-ism" but I gotta believe you can pay for a lot of punctured vollyballs for what it would cost you to pay an ironworker to snip or cap protruding screws. How often does it happen that a ball gets up that high and happens to hit a screw with such force that it punctures the ball? I think your architect is overthinking the issue. Of course, once a kid figures out that it can happen, I guess they will make a game of trying to make it happen. George A. Everding AIA CSI CCS Cannon Design - St. Louis, MO Lynn Javoroski CSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 857 Registered: 07-2002 Posted on Friday, March 27, 2009 - 10:03 am:    Couldn't they just be dipped in or coated with a dab of epoxy to take the edge off? Doing it in the same color as the underside of the deck would make them less visible (or a contrasting color would give a lovely polka-dot pattern - LOL) and if a ball got punctured, perhaps the cause would not be evident. Is the underside of the deck to be coated anyway? Curt Norton, CSI, CCS Senior Member Username: curtn Post Number: 142 Registered: 06-2002 Posted on Saturday, March 28, 2009 - 04:25 pm:    It does happen. I have wokrked with a lot of schools and it comes up. Once kids find out that a ball can be popped by hitting the ceiling, a new game develops. Just like when you have duct work that catches balls. The better answer is to ballast your roof or use adhesive instead of fastners. There are plastic screw screw tip covers that can be used. (Durolast came up in a google search) It's not as pricey as you would think, but it's still not cheap. They can be installed by general laborers. Ralph Liebing, RA, CSI Senior Member Username: rliebing Post Number: 969 Registered: 02-2003 Posted on Monday, March 30, 2009 - 06:58 am:    Understand the concern and the covers and coatings are good ideas, but one of the last large deck projects I did involved 21,000+ fastners. Here I would think the labor at least begins to become a factor. To say nothing of the staging, etc. to get the workers to the underside of the deck, and getting a decent uniform installation [like an added inspection].