I am going with cor-a vent and hardie plank cement siding for most of my exterior (OSB and housewrap) . My problem is that my poured concrete foundation is not square with the (square SIPs house on top). The SIP walls stick over the foundation by 2 inches in some corners and the opposite corners are about 2 inches inside the foundation. I am thinking of a natural rock wainscot to hide this and it would extend about a foot above the foundation onto the SIPS (OSB with housewrap).  I would have a 4 in brick/ledge flashing separating the hardie planks and the rock wainscot (with a flat top such as sandstone) I have read the discussions on providing an air gap between the foundation and SIPs plane and the rock wall. Yet I am thinking that painting the SIPS area behind the rock wainscot with some thing like envirodri or applying ice and water shield membrane would be a good idea.  I am not sure how to manage an air gap between the SIPS/concrete foundation that is crooked, and the rock wainscot.

Any advice would be appreciated, yes we have lots of rocks!
Kirk.

Kirk - are you talking real rock? How are you attaching/supporting it?

If you are supporting the rock with a bolted on angle iron and then with masonary ties to the wall, I would lay up the rock to the finished height and then install brick breather vents (small plastic grilles designed to fit in the grout line of brick and available at most masonary stores) in the grout line between the rock and the sandstone water table. You could also use pieces of the cor-a-vent. The rock would be laid up with a 1" gap behind it, with house wrap (or peel and stick) starting above the water table line, over the sip and foundation to direct the water out over the angle iron. (don't forget weeping holes at the bottom) The sandstone water table would go tight against the peel and stick. Install the wall flashing over the water table and start a new piece of house wrap over the flashing and going up the wall. Strap the wall for the hardie keeping the straps at least a half of an inch above the flashing. Insert the cor-a-vent between the straps and start the siding, leaving the 1/2" gap between the bottom of the siding and the flashing on top of the water table.

If the outside skin of your SIP is not supported then you could have a structural issue.

Thank you for the advice.  So I infer that housewrap is sufficient between the rock wall and the OSB SIP/rim board area?  I was thinking of an anti-mold paint or enviro-dri or ice and water shield, is that overkill?  Also what do the weeps at the bottom of the wall look like? Do I need flashing here as well or just weeps?

To support the rock wall, I am considering having (the same contractor who poured my out-of-square foundation), pour a ledge against the existing foundation that would be 6" thick and reach down to the footer, this would be poured up to grade level. The other option is attaching angle iron but it seems to me that 6 in angle iron would be heavy and expensive and difficult to install.