i-joists for loft floor

[beckhamk]

Any one here use i-joists for their loft floor?  I am curious as to how you connected them to the cut in ledger?  I noticed on Dave & Kims 20x40 on the main site they just sat the joists and i assumed nailed them to the stud and ledger. Has anyone use a simpson strongtie and had the joists hanging from a hander off of the cut in ledger?

[rwanders]

The manufacturer provides very clear and mandatory details for installation of I-Joists and the methods of connections. They are amazingly light and strong but, if you do not use as directed, they can lead to structural failures. They are similar to trusses in that seemingly small deviations can defeat their ability to transfer load stresses safely. The dealer or distributor can also provide guidance and appropriate hangers for your use. 

[beckhamk]

Thanks rwanders, i have all of the information i needed from the manufacturer.  It was more of a question on how exactly some of the others have used it for the loft floor.  I dont recall seeing anyone use the top handers, only sitting the joists on the ledger which i dont think is wide enough.

[Don_P]

I thought I had responded but it's been a brain frying week  .
If the roof system transmits any thrust to the walls the loft floor is acting as a tie to keep the walls from being pushed outward. Joist hangers and especially I joist hangers have little to no strength in that direction.

[rick91351]

Good point Don_P.  I had noticed that but it never clicked.  I knew I was seeing something with those hangers yet was not connecting.      Thanks for pointing that out. 

[Don_P]

I had that section open a few minutes ago for something else and reread that part. If you use a let in ledger the joist is to sit on the ledger and be lapped along and nailed to the stud.

There may be more to think about than is apparent here. Nailing the center osb web to the stud, with blocking to pad it out, would need to be checked and a detail drawn. Technically by the suppliers engineer... and I expect they'd do it for free. Nailing in that direction through the flanges is forbidden in all the specs I recall.

When working with "engineered" products as opposed to dimensional lumber, the supplier should provide any details, stamped if needed, as part of the service. Another good resource when you have questions about these products: The APA (American Plywood Ass'n)... ply, osb, lvl, glulam,TJI, etc) has a helpdesk on their website that is staffed by engineers and they do answer their email; apawood.org

[John Raabe]

If you using my plans you can modify the detail on Sht. 5 where the 2x12 loft joist sits on top of the ledger, then overlaps and is well nailed to the vertical balloon framed studs. With I-joists you would infill both sides of the flange with a backer block or web stiffener to get solid nailing and provide a tension tie into the I-joist. Confirm this with the supplier.