Cold Formed Steel Ledger Connection @ Loft Infill/Platform 1

[FoxSE14]

I am designing a new cold formed steel loft to be constructed within the confines of existing wood stud walls, so I have a ledger condition along the perimeter. I am sure this has been tackled before using CFS, but I am having a tough time quickly finding a typical approach to this detail. My concern with using a CFS member as the ledger lies in the local effects (warping, fastener tearing/pullout, etc). If forced into CFS ledgers, I personally would gain some comfort by doubling up the ledger member and drive the fasteners through the nested webs, possibly adding stiffeners/some connection to tie the top & bot flanges. Any CFS experts out there?

On the attached sketches, I prefer approach #2 for both the "joist perpendicular" and "joist parallel conditions" (biggest driver is my limited experience using CFS and preference toward wood). I'll be dumping approximately 400# at the joist perpendicular connection. Is it so crazy to have a CFS contractor cut a few wood ledgers? Seems reasonable to me.

Our office has limited experience with CFS, so, I welcome any input/feedback - thanks in advance!

 

[mike20793]

Check out the Simpson cold formed connectors. They have quite a few connectors for cold formed steel to wood or vice versa. It may help simplify your detailing some.

 

[KootK]

This too: Link

My gut sense is that you want option #1, single ply, no flange to flange stiffeners. It looks conventional and reduces eccentricity. I feel your pain though. Hybrid connections are always a pain.

I'm going to mentally summon XR250 to your thread for you... now! He's a wiz at this stuff as he does specialty work in CFM.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[FoxSE14]

Thanks Mike - I took a look at that publication and it gave me the idea for the SJC and S/JCT connector shown in my sketch. Have you, or anyone else, specified anything similar to the ledgers I showed? Or have you gone a different/more creative direction entirely?

 

[KootK]

For option #1, I was thinking that the joists would actually be nested into the track.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[FoxSE14]

Thanks KootK -- wow, you're over my shoulder -- I am browsing the same document as some frantic googling led me to the same within the last hour or so! Great reference that I'll be keeping for future CFS projects.

 

[FoxSE14]

KootK - yep I follow. The only reason I went away from that is because I was thinking that I want lips on the ledger since it may need to span between existing studs (although, with wood backup studs at just 16", perhaps I am overthinking and a traditional "lipless" track will suffice). Can you tell I normally don't deal with CFS?

 

[XR250]

I like option one for joists perp. and either option for joists parallel.
What is the joist span, design loads and are the joists intended to brace the walls?

 

[FoxSE14]

Joist span is 11.5', say 12psf DL & 40 psf LL. Joists are not intended to brace the walls (walls are part of existing residence).

XR - thanks. I am leaning toward modifying my approach to choice 1 for joists perp by doing something similar to what KootK suggested, i.e.: use a typical track ledger and avoid eccentricity that the Simpson SJC is imposing. Any opinion on that?

 

[XR250]

I typically use the track as a ledger for 8" joists even though I think the CFS spec for designing those maxes out at 6". Your point load is about 400lbs at each joist. I would not worry about using a 16ga track and calling it good. Might want to go to a 14" track for giggles. For the parallel case, anything is going to work.