I joist vs 2x12 for loft- need input

[free07110]

Building bedrooms inside my barndo and will have loft above bedrooms. 9ft bedroom ceilings and loft area will be around 14ft by 25ft deep. The building itself is 30x50x12 6/12 pitch. I’m debating on doing 2 x 12 for floor joist or looking into getting I joist. Spacing will be 16” oc.

Does anyone have experience with I joist vs 2x12? I planned to do 2x12x20 side to side and overlap over the hallway. But also trying to research I joist and if that’s a better option. Want to make sure my second floor loft area doesn’t flex.

 

[CraigStu]

W/o getting into tables etc this was my experience when talking to the builder when redesigning one of his standard floor plans. He said 2x10s on 16" centers span 14ft. This was standard for a 2 story house. You may want a little more stiffness for a loft than for our bedrooms so I'd think 2x12s would do the job. Of course further stiffening would be easy by going to 12" centers.

 

[Rusted Nut]

20’ 2x12? Those are not very common, and might not be available. I’d use I joist. Lighter, stronger, and they won’t warp.

 

[free07110]

W/o getting into tables etc this was my experience when talking to the builder when redesigning one of his standard floor plans. He said 2x10s on 16" centers span 14ft. This was standard for a 2 story house. You may want a little more stiffness for a loft than for our bedrooms so I'd think 2x12s would do the job. Of course further stiffening would be easy by going to 12" centers.

Thought of doing 2x10 on 12” oc at first but don’t know if that would be better than 2x12 on 16” oc.

 

[larry4406]

I like I-joists. They are vertically dimensionally true one to the next. You get straight floors and straight ceilings.

2x12’s typically vary 11-3/8 to 11-5/8”. Since they sit on the wall sill plates, you get a good ceiling below, but the subfloor above needs to bow and contort as the top surfaces are not in a same plane. This contributes to floor squeak's.

 

[jar944]

The floor framing in my house is 14" I joists on 19.2" centers.

I would have preferred to frame my deck with i joists vs 2x10s if I could have.

 

[Hank11]

Perhaps I do not understand your question. It appears that whichever direction you run your floor joists on top of the walls below you’re gonna have plenty of support. The biggest span looks like it’s about 13 or 14 feet. 2 x 12 or even 2 x 10 over that distance will be nice and stiff. You should build good headers over those door openings sufficient to support the load above evenly.

if you have plans for an unusually heavy floor load, you could ask an engineer to make sure you build it stout enough.

 

[firebirdparts]

Either one is overkill with that floor plan. 2 by 10 adequate.

 

[free07110]

Either one is overkill with that floor plan. 2 by 10 adequate.

I originally planned 2x10 on 12’ OC. Still might do that. I joist can be expensive compared to 2x12 or 2x10

 

[free07110]

Probably end up with 2x12 or 2x10. One side I can cover the hallway with 16footers