Question about decking.
Question about decking.
(OP)
I have a client who wants to put a 1.5 inch decking on the bottom of some bar joists to be a ceiling for this one room in the building. He also wants the maintenance guys to be able to walk on it. I spaced the joists at 4' so the loading on the deck shouldn't be a problem, but I'm worried about the strength of the screws holding the deck onto the bottom chord of the joist.
Is there anywhere I can find published holding strength of screws so I can size and space them properly? Is there anything else I'm overlooking?
Is there anywhere I can find published holding strength of screws so I can size and space them properly? Is there anything else I'm overlooking?






RE: Question about decking.
1) local bending of the bottom chord.
2) drilling holes through the bottom chord.
3) minimum deck bearing (1-1/2" in my area).
There may be other problems.... but those just popped into my mind.
As far as screw values, ITW Buildex is where I go to answer all of my screw questions: http://www.itwbuildex.com/index.html
RE: Question about decking.
Unless they use very large washers with bolts it is not a good situation. Even then it is not a good idea.
The added cost of placing some 2x or 3x on top of the bottom chords (of the bar joists) at whatever spacing is needed for the maintenance guys will be worth it in the long run.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Question about decking.
RE: Question about decking.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Question about decking.
As a ceiling, the decking can look nice. But it is as good as gypboard is for a walking surface IMHO when hung from joists.
If you (or if the client insists and you are willing to go along) still want to design it, make sure (if you are in the USA) to follow the NDS or an ICC ES report for the values. I would recommend that you use at least 40 psf live load with only 50% of the connection values if you go this way.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Question about decking.
RE: Question about decking.
RE: Question about decking.
RE: Question about decking.
M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)
RE: Question about decking.
RE: Question about decking.
Why would pre-drilling be required? I have never seen a joist chord that a TEK screw cannot go thru.
Contrary to what others say, you are not going to hurt the joist by adding some screws to it - unless it is designed to bare minimum code. Many are sized for deflection anyway. You are also not going to hurt the bottom chord by stepping on it - sheesh, how conservative can you guys be?
As long as your decking is 22ga or greater, you are not going to pull a screw thru it either - even if you had a 300 lb worker up there, there is some much redundancy with all the fasteners that a complete failure is unlikely.
RE: Question about decking.
You may be right that predrilling would not be necessary, but we don't know the span or the thickness of the chord members. I wouldn't like to try screwing overhead into 1/4" steel without predrilling.
RE: Question about decking.
A Tek5 self-drilling screw will drill just as fast and easily as a normal bit.
Most Bar Joist flange thicknesses are only about 1/8 to 3/16" anyway
RE: Question about decking.