I am drawing up plans for a home renovation of an existing sips home.  In an existing two story space the homeowner would like to have a 2nd floor.  My thoughts, for the purpose of supporting the loft floor, is to have a balloon frame using metal joist hangers placed at the top and bottom let-in plates of the existing exterior sips walls.  The tributary area supported by the hangers is aprox. 7'-6".   I would likely spec 2x10's @ 16" OC.  Any thoughts or suggestions?  I am woefully unfamiliar with sips construction... having a very painful learning curve with this project.

My first thoughts would concern the size of the panels, and the spline system used for installation. What is the thickness of the panels? If the panels are 6" thick, 4' wide by the height of the room, with 2x6 vertical splines 4' on center, then a let-in 2x10 rimboard lagged to the splines should provide a fairly stable starting point. Thinner panels, 8' wide panels, or splines other than 2x's will create a more difficult problem to deal with.

Don't let anything into the inside skin of the panel. As soon as you start cutting your creating a weak spot in that panel wall. What type of exterior finish is on the home. If you can take a couple of pieces of the siding off you can use a deck ledger conection. This connection is one that we have used many times in the past to hang ledgers for both decks and second stories. The ledger would be either 2x10 or LVL material riped down to 9 1/4". Once the sheet rock is removed and you have the exsposed OSB on the inside of the panel use sub-floor adhise and screw the ledger to the inside skin at the required hieght of the floor system. Then you go around to the outside of the wall and screw throught the wall system with SIP screws and 2" wahsers into the ledger locking it into place. Make sure the SIP screws are long enough to penitrate into the ledge without going all the way through. Ocne the ledge is in place you hang your floor joists off it like any other hangered floor system.

I have the technical drawings if you would like to see them.

Andy in wisconsin