I'm having a hard time finding a good detail for the connection of the first floor deck and SIP wall, to an 8" poured concrete wall. The foundation wall will have 2" of Rigid insulation on the outside. Can the sill plate and show plate overhang the foundation at all? Please see my attachment.

I should add that the house will be a ranch style, with conventional roof trusses sitting on the SIP walls.

If my understanding of sips is correct, it is the skins that bear the load and must be supported. In your sketch the outside skin is bearing on the 2 x 12 which is over the foam.

Some engineers will let wood bear on a 45º but that is usually for end grain. In this case if you trace the truss load down, it lands on the foam which has no bearing capabilities.

That's what I thought. It's hard to find a good detail for this. Nothing online, searching. Every detail I found would show a foundation without any insulation. Attached is my plan 'B'.

That would get the support out where you need it.
A 6" ICF with a brick-ledge either to the inside or outside would be better and depending on where you are building, probably cheaper.

You could also add a rain screen behind the siding to get out to the plane of the foam, which I assume is your goal.

Hi,

We just finished a SIP panel ranch (inside area approx 1430 SF) and did things a bit differently from that shown in your detail sketch.
Walls are 6-1/2" SIP's

10" foundation (front wall is fairly long at 52')
Vertical wire chases in the SIP's at every point we have an outlet or switch
Conventional floor system sitting on top of the concrete foundation
SIP walls sit on top of the subfloor
Holes in the subfloor to line up with the chases in the SIP's
No insulation on the outside of the foundation
1" rigid foam, Ecostuds, and 3-1/2" Roxul on the inside foundation wall (approx R20)
OSB sheathing inside
3" of closed-cell foam on the rim joist (approx R21)
Trussed roof with 12" bottom chord that sits on top of the SIP wall
Accuvents for roof ventilation (with full length soffit and ridge vents)
2" of closed-cell foam over the ceiling to seal it (approx R14) plus something like 14" or 15" of cellulose (total R63)
All seams, windows, doors, sealed with SIGA tapes (from Small Planet Workshop)
Imperial DH7.15 HRV in the basement

The house is in Maine - pellet stove in the basement has not been used - heating with a single Fujitsu RLS2H 12,000 BTU mini-split system with one head at one end of the house.

Cal
Gray, ME

Posted By NFC on 13 Dec 2013 12:58 PM
You could also add a rain screen behind the siding to get out to the plane of the foam, which I assume is your goal.

Even with a rainscreen you still need a space to allow the air to enter the gap at the bottom of the siding. Hate to shave the foam off the foundation for that. Don't all ICF foundations have this same problem? How do they solve it? I have also searched the web for more information and some say they have cantilevered up to 2" with no problem but I suppose that doesn't mean a PE will approve. Here is a detail on edgewater house that shows overhang of a sill plate on top of a taper top icf. http://edgewaterhaus.com/wp-content/uploads/2011/06/1008_Normand_10-A3-2-1-2-Wall-X-Section1.pdf

For anyone browsing this topic, here are a few details of non sips sill plates with 1.5" overhang from Wisconsin http://dsps.wi.gov/sb/docs/sb-UdcQAsillOverhang.pdf

Here is a prototype (untried) design I came up with for a studded angle at the exterior face of the poured wall.