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RE: Steel Roof Deck Attachment Question

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I went through the same situation about 6 weeks ago on a much smaller
project than Mr. Caldwell's.  The contractor suggested using the Fablok
fasteners; however, I rejected their use.  After researching the fasteners
and talking with their "research" department, I was informed that they did
not have ICBO approval.  The project was behind schedule and everyone was in
a hurry, so I did not extend my research to the steel deck institute.  I
would be interested to hear their input.

Brian K. Smith, P.E.

> -----Original Message-----
> From: Caldwell, Stan [mailto:scaldwell(--nospam--at)halff.com]
> Sent: Friday, June 23, 2000 10:32 AM
> To: 'SEAINT Listserv'
> Subject: RE: Steel Roof Deck Attachment Question
>
>
> Charlie:
>
> I have been dealing with this issue for the past month.  We have
> a recently
> constructed 200,000 s.f. industrial building project that is concrete
> tiltwall construction with a steel diaphragm roof deck supported
> by open-web
> steel joists and joist girders.  At certification time, we discovered that
> the roof construction had never been inspected.  Upon removing about 1% of
> the roofing to perform an inspection after-the-fact, we
> discovered that the
> deck was inadequately connected to the joists and, as constructed,  was
> capable of transmitting only about 55% of our design shear
> forces.  Repairs
> would be necessary before the building could be certified, and time was of
> the essence because a contract was pending for the developer to sell the
> building.
>
> We proposed removal of the roofing, followed by inspection and repair from
> above.  The contractor objected, on the basis that this would
> cost more than
> $500,000 and result in nasty litigation.  He proposed installing "pop
> rivets" from below.  We objected, on the basis that we could find no
> evidence that the proposed rivets, which are intended for use in the
> manufacture of truck bodies, would adequately clamp the 22 ga. steel roof
> deck to the chords of the joists.
>
> Finally, we found two products that we were able to accept for making
> repairs from below the deck.  They are GESIPA Olympic Bulb-Tite Rivets and
> FABCO (Camcar Textron) Fab-Lok Fasteners.  I would describe both fasteners
> as being "industrial strength molly bolts".  Repair work
> commenced this week
> using the Fab-Lok Fasteners.  If you use either of these products, please
> note that:
>
> 1)  The shear strengths quoted in the manufacturer's literature are
> irrelevant.  This is for direct shear across the throat of the
> fastener, as
> if two relatively thick pieces of steel were being connected.  For the
> connection of roof deck, the reliable clamping force is much more
> important.
>
> 2)  Flanges of your W shapes are much thicker than the thicknesses of our
> Vulcraft joist chord angles.  Pay attention to the exact dimensions of the
> fastener you select, and ensure that it can handle your thickness.  Also,
> the relatively narrow width of the deck flutes will influence
> your fastener
> selection.
>
> 3)  Make multiple tests and carefully observe the results before
> proceeding
> with the overall construction.  We stripped off a chunk of
> roofing this week
> and observed from above and below while the contractor installed the first
> 20 (+/-) fasteners (of nearly 50,000 required).  We worked with the
> contractor to determine what procedures gave the best results.
> Among other
> things, we concluded that the fasteners were only reliable with one ply of
> decking, so we adjusted the repair pattern to avoid side laps (2
> plys), end
> laps (2 plys), and corners (4 plys).
>
> 4)  You will find that these fasteners are quite expensive when compared
> with typical steel deck fasteners installed from above (puddle welds, seam
> welds, powder actuated fasteners, and tek screws).
>
> 5)  Special installation tools are required, and they might not be readily
> available.  At least, not until our project is completed!;^>
>
> I hope that this information is useful.  If you want more detail, just
> contact me privately by email or telephone.
>
> Regards,
>
> Stan R. Caldwell, P.E.
> Vice President
> *************************************
> HALFF ASSOCIATES, INC.
> Engineers+Architects+Planners
> 8616 Northwest Plaza Drive
> Dallas, Texas    75225
> Phone:  (214)346-6280
> Mobile:  (214)236-9696
> Fax:      (214)739-0095
> Email:   scaldwell(--nospam--at)halff.com
> Website:  http://www.halff.com
> *************************************