TGI floor joist max hanging weight

[JMER817]

Working on finishing my basement. I have 11 7/8 TGI floor joists that I will be attaching drywall to. There is the furnace ductwork that I had to build a soffit around to cover. The soffit comes out over 6ft from the beam of which the TGI is resting on. I'm trying to find information on how much the bottom cord of the TGI joist is capable of holding before the possibility of separating. Scanning the internet I'm not finding a whole lot of information. In a variety of TGI technical online guides it shows in some cases of two layers of drywall for fire rating in some localities. So it must hold a fair amount? I'm only using one layer but in the area where the soffit is build combined with the ductwork and drywall could get on the heavy side. Think I'm ok? What's the best way to reinforce if not?

 

[JMER817]

Pictures are rotated CCW for some reason

 

[EddieWalker]

If you click on the pictures, they come out correctly. Not sure why the thumbnails are sideways.

From what I'm seeing in your pictures, you hung some OSB off of your joists, and then attached 2x6's to the osb. Is that accurate? How did you hang the OSB off of your joists?

If it was me, I would install blocking between your joists and metal strapping to that OSB you have hanging off of it. I don't think joist hangers will work to attach those 2x6's to the OSB, so I would probably run the strapping from the 2x6 up the OSB and to the blocking. The blocking will spread the load for you.

 

[robstaples]

My house is tji rafters. When there was a connection, they filled in the web. I'd recommend a one piece 2xX knocked for the flanges, top and bottom , and then glued in place against the web. Clamped until glue dried. Every other joist seems reasonable. Might be over the top. But piece of mind is worth a lot.

 

[Citydude]

If you ran a 2x4 perpendicular to the joists, screwed on each joist, then attached your osb to that, your good. Hard to tell from the pics if you did. I don't have the experience Eddie has however I had the same senerio having to span 6 feet over duct work with drywall. That's a lot of weight.

 

[JMER817]

If you ran a 2x4 perpendicular to the joists, screwed on each joist, then attached your osb to that, your good. Hard to tell from the pics if you did. I don't have the experience Eddie has however I had the same senerio having to span 6 feet over duct work with drywall. That's a lot of weight.

Yes I ran a 2 x 4 perpendicular to the joists (attached by 2 3" screws in each joist) then attached the OSB to that 2 x 4 with constructions screws every 8 inches or so. Those are 2 x 4's spanning the ductwork. My concern is the bottom flange of the TGI floor joists separating.

 

[Rustyiron]

You're good to go! Hang it!
That little bit of framing (and drywall) is not going to separate that lower "cord". The glue is the whole basis of strength on a TJI.

 

[Larry Caldwell]

You don't hang from the bottom chord on a TJI, you hang from the center of the web. It will handle drywall just fine, though.

 

[JMER817]

I contacted the manufacturer of the joists and sent him pictures. He said I should be fine. I figure there is about 700lbs in the 7ft x 14ft area (framing, ductwork, drywall) with 20 attachment points (two per joist) which equates out to 35lbs per attachment point. Even less since I am also attached to the wall on the one end. All of the I joist manufactures show a fire safety option of hanging 3 layers of 5/8 drywall to the bottom of the I joist. That would equate to 650lbs based on 2.2lbs per sq ft for 5/8 drywall. I always like to add an extra bit of insurance in anything I build, but there is just no room to add any blocking due to all the ductwork, and wiring passing thru. There are a couple points along the complete soffit (42ft long) that I could squeeze in some type of web reinforcement to attach to. Don't think that would make much of a difference.