LGMF - Ledger over gyp board at fire wall - does this exist?

[MidwestSE]

Is anyone aware of a detail to put a track section against an existing LGMF stud wall (fire rated) that is rated (has an ICC/equivalent report) for use over 2 layers of gyp board similar to what simpson has for wood ledgers used over a layer or 2 of drywall?

Thanks!

 

[phamENG]

Can you post a sketch of what you want? It sounds like you want to use a track as a ledger, which generally doesn't work for anything heavier than an acoustic tile ceiling.

 

[MidwestSE]

I would envision using a track as a ledger with the track fastened through the gyp board layers to every stud, so it should work since the spans are only 16" between supports.

My bigger question was if there are any screws or assemblies rated for this (we could use a C8 as a ledger if we needed to).

Thanks!

 

[phamENG]

My concern would be the connection of the joist to the track. How much do you think you're going to support bearing them on a 1.5" long, light gauge piece of steel? Like I said, anything heavier than a lightweight ceiling with no live load probably won't work. (I know because I've done the calcs.)

 

[XR250]

I think AISIWin has a module for that calc and the capacity is actually pretty OK. I think i have used it before for a floor load with short span joists.
I think the track to stud screw does a lot of the work.

 

[phamENG]

I'd love to see it. I use clips for that condition because I've never been able to make them work. Maybe going with a really heavy track and with very short spans/light loads it could work, but I haven't come across one.

MidwestSE - This may be your best option: S/DHUTF Drywall Hanger

 

[MidwestSE]

@XR250 - same for this case, the trib width on the ledger is like 3' max. My plan would be joists to ledger w/ typical clip, ledger to studs w/ screws.

@phanENG - I looked at those. I don't think I can get them to work (this is a mezzanine framing into an existing wall at mid height)

I'll post a detail when I get this wrapped up.

 

[Aesur]

I'm with everyone else here for using CFS as a ledger, but I could think of ways it can be made to work if needed, so I'll avoid that discussion. For the attachment, I believe Simpson and Mitek both make screws that are designed to attach ledgers over up to 2 layers of gyp and provide decent connection capacity. We have had to do this a few times for fire assemblies. I believe they are the SDWS for Simpson and WSWH for Mitek. Since these are wood screws you will need to calculate the penetration through the CFS steel ledger, but that is a few simple checks.

 

[Aesur]

I completely missed that you are attaching to a steel stud wall. The screws above are for wood, so may not be an option.

 

[Eng16080]

This type of detail is always such a pain. I've never used a ledger over drywall like you describe, only the DHUTF connector detail mentioned above.

If this were wood framing, I would mention AWC-TR12 which provides equations for calculating lateral fastener capacities with a gap between the connected pieces. I've never looked into it too far, but I would assume the capacity goes down a lot as the gap increases. For a small screw with a 1.25" gap (assumed), I doubt there's much capacity. Does the CFS code have a similar type of calculation?

 

[MidwestSE]

For anyone wondering, I stuck a joist through the wall every 4' and headed everything else off at the wall with beam right next to the wall.

 

[lexpatrie]

Span it the other way?

There's a difference between attaching to a fire-rated wall and attaching to a fire wall.... you seem to be aware of that, however.