[3Dsigns]

My steel building has horzontal z- purlins framed about 7'5'' off the floor. If I use 2x4 studs with a doubled top plate, under the z-purlins on my steel building to hold up one side of a wood "mezzanine" floor, and use a ledger board, #1 would this be the correct way to do it? #2 will 1'' be enough?(2,5'' with the ledger board)?? or do I really need to use 2x6's for my stud wall?
Note, as shown in the drawing, the lip of the z-purlin would hold the cap joist off the wall by 1'' which causes part of the problem. Thanks

 

[3onthetree]

Are the purlins mounted outside of the "red iron" structure or in between? My first thought is not fond of putting anything attached to the enclosure, it moves and needs to move way too much.

 

[3Dsigns]

Are the purlins mounted outside of the "red iron" structure or in between? My first thought is not fond of putting anything attached to the enclosure, it moves and needs to move way too much.

In between. Bolted to the I-beams at each end.

 

[3onthetree]

I picture this mezzanine being attached to 3 walls. It would probably be better to use the wide flange post structure to provide the lateral bracing rather than the metal siding enclosure. So independent of the z shapes which means it is set back from the exterior wall.

 

[3Dsigns]

I picture this mezzanine being attached to 3 walls. It would probably be better to use the wide flange post structure to provide the lateral bracing rather than the metal siding enclosure. So independent of the z shapes which means it is set back from the exterior wall.

It will be braced by 4 I-beam posts, which are 25' apart, and will be laterally braced by 1/2'' plywood over the supporting walls.

 

[Missouri Bound]

How long are these 2" X 10" joists?
How large of a span?
How big is this mezzanine?
You aren't running 2" X 10" joists unsupported for a 25' span......are you?

 

[3Dsigns]

How long are these 2" X 10" joists?
How large of a span?
How big is this mezzanine?
You aren't running 2" X 10" joists unsupported for a 25' span......are you?

2x10 joists are to be 13' long. supported on a 25' stud wall at one end and a 5.5x9.5 beam on the other. The beams will span 14' each

 

[Calson]

Structural screws do not begin to have the shear resistance for such an application and they will not resistance lateral movement and can easily pull out. Overall it is a bad design that may fail and cause serious injury to anyone below the structure.

Strongly suggest talking to someone at the company that makes the steel building for advice. The 2x4 studs may not be able to support the load of the mezzanine and its contents and the people at the steel building company will know this as well.

 

[Nealtw]

Would build the wall out of 2x6 for the insulation value

I would cut the the rim joist to be above and below the steel

You need to use hangers only to get a good attachment to the rim.

Screws because they will pull the rim tight

Screws or nails down thru the hangers tie the floor to the wall.
No need for a ledger.

As was there was no shear load on the ledger and it could have been less just to take screws from above.

 

[P C D]

My steel building has horzontal z- purlins framed about 7'5'' off the floor. If I use 2x4 studs with a doubled top plate, under the z-purlins on my steel building to hold up one side of a wood "mezzanine" floor, and use a ledger board, #1 would this be the correct way to do it? #2 will 1'' be enough?(2,5'' with the ledger board)?? or do I really need to use 2x6's for my stud wall?
Note, as shown in the drawing, the lip of the z-purlin would hold the cap joist off the wall by 1'' which causes part of the problem. Thanks

If you connect the 2x10 ledger board per NDS to the 2x4 top plates and studs, your bearing length will be 2.5" , which should be good enough (nail it!)