This 2 story with walk out basement is being done by owner/builder , balloon framed walls as tall as 35ft. Owner is doing a great job!
Roof is 10/12 pitch

My house design is pretty much done (in SC, no less) so what would be the next step? Does the steel SIP manufacturer make the panels to fit my design? Are steel sips load bearing, or do I need to find another way to hold my 2nd floor up? The only 2 story walls are on the gable ends; everything else is under the roof, which is 12/12 on the main gable, and goes to 4/12 over the wings and porch. Would SIP's be prohibitively expensive for the porch roof, or would I be better off using conventional framing? I have over 800 sq ft of covered porch on a 1200 sq ft house, so I need to keep the costs down. Needless to say,I have a lot of questions about steel SIP's!

"Prohibitively expensive" really depends on how fat your wallet is, but I think the question is whether the payback is there.  If the porches are conditioned, it may be a good idea.  If they are unconditioned space, SIPs are expensive without offering much benefit.  For conditioned spaces, a SIP roof will generally be more expensive than a conventionally framed uninsulated roof with an attic and blown-in insulation on the attic floor.  But in my opinion that's not a good way to build.  You want the insulation and air sealing on the roof, not on the attic floor.  So when comparing costs, compare it to other insulated/sealed roof options, of which conventional framing with spray foam under the roof deck is the most common.  At that point, the cost gap is much narrower.  If you want a cathedral ceiling or livable attic space, you have to use rafters instead of trusses, which tilts the balance further toward SIPs, since they are themselves structural and need less framing underneath them than a spray-foam roof deck.  Often a ridge beam supported by your gable walls is all you need, leaving the space below the roof completely open.  (This depends on spans, of course; you may need additional support.)  The beams can be left exposed and stained/painted to become an aesthetic feature in a cathedral ceiling.

Steel SIPs are load-bearing.  No worries there.

rnortman;

one needs to consider that the steel SIPs for a covered porch provide the framing, deck substrate and an attractive prefinished white soffit, the bonus is it's insulated too!
When its all said and done no more expensive than conventional framing, deck, soffit and much faster & easier to install.

jdebree;

 

I just sent you an email, 2 nd floor is attached to inside skin of panel as shown on attachment

Chris- Thanks for the info you sent me- I sent you a reply. In that picture, it looks like the plywood subfloor is screwed directly to the metal joists? FWIW, my porches all have a 10' free span with a 4/12 pitch- is that too much for a roof SIP without additional framing? I think the snow load in my area of SC is 10 or 15 pounds. Since we will be on the porches a LOT, I like the idea of an insulated roof. In one house, we had a porch roof made of aluminum roofing pans. After a couple of years, we added foam insulation- what a difference! It was also a lot quieter in the rain. Another question- what kind of span can those metal joists handle- say for a 30# live load, as in an upstairs room?

jdebree;

the plywood is glued & screwed or fastened with balistic nails shot with a pnuematic nail gun capable of penetrating 14 ga. steel

a 6" Steel SIP @ 10 ft clear span is rated at 105 lb. total load

The deitrich "Trade Ready" steel joist system is cabable of clear spanning 32 ft., size , ga. & spacing depends on span/load

32' is impressive. I'd like to span 28' in my barn loft- I may have to look into those.

you can also try http://www.marinoware.com/Products/joist_rite.asp