Just got back from a trade show in Italy where traditional timber frame was being exhibited. The standard practice there is to put thick fibreboard panels directly onto their OSB outersheeting with some kind of vapour barrier or breather membrane. They then render directly onto this fibreboard with mesh and stucco.

With SIPS I always put at least a 1 inch cavity between the breather membrane (which is attached to the outer face of the SIP) and the inside face of whatever the cladding material is, be it brick, cement board or siding.

Seeing this got me thinking, do we really need that extra cavity? We are in a mediterranean climate here so extremely low temperatures are not the issue and I liked the idea of a rigid board straight on to the SIP, giving a more solid external finish, as opposed to a hollow rendered board.

Jazzdude;

you need a 1"gap for brick but not for stucco or siding

What you need to do is definitely dictated by climate. You can't really generalize and say 'in Italy they do this'. Italy has many kinds of climate. It has warm coastal regions, cold mountainous regions, etc... If the region you want to build in is warm and dry, then you can probably get by without the cavity. If walls are protected with large roof overhangs and your exterior wall finish is dense and water resistant, this also keeps water from getting into the wall. Building is a very regional practice and building systems have evolved to suit the regions they occur in. A cavity would definitely be recomended for a damp climate.