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Unread 11-24-2020, 09:24 PM   #4
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Join Date: Aug 2020
Posts: 68
Demonic cx is incorrect in stating sistering your tgis is ineffective, it doubles their strength. Yes there is a cost associated with purchasing that much lumber, but it is one option to easily diy double the strength of the 16' floor. You can also RIP osb and attach to the sides as a stiffener, which is usually the choice of manufacturers when cantilevering.

26' width is about 20 tgis
If you installed 1 per joist it's about$500 in lumber. 2 per joist$1000.
Ripping lengths of osb would be half that, or less.

Different options, different cost, different results.

Metal strapping is my preference over wood strapping, because you can add sheetrock right over it in the future. Which you may find installing plywood or gypsum to the ceiling to be attractive one day, to separate your workshop noise/ dust from your dining room. That load should be factored into the equation before choosing a solution.

Blocking/ strapping allows the joists to somewhat share the load, however is more effective in dimensional lumber framing, than with tgis.

You probably have 1/16" deflection over 16' , osb rips could probably bring that down to 1/10,000" or basically nothing.

Any architect/ engineer with the manufacturer's tables could tell you how to best get to your desired deflection. Or of course the manufacturer can guide you directly.

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Last edited by mykcuz; 11-24-2020 at 09:36 PM.
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