Alberta Building Code - Flashings

Here is the what the Alberta Building Code (1997) has to say about flashing:

9.27.33. Flashing

9.27.3.2. Installation

1) Flashing shall be installed at every horizontal junction between 2 different exterior finishes, except where the upper finish overlaps the lower finish.

2) Except as provided in sentence (4), flashing shall be applied over exterior wall openings where the vertical distance from the bottom of the eave to the top of the trim is more than one-quarter of the horizontal overhang of the eave.

3) Flashing shall be installed so that it extends upwards not less than 50 mm behind the sheathing paper and forms a drip on the outside edge.

4) Where a window or exterior door is designed to be installed without head flashing, the exterior flange of the window or door frame shall be bedded into a non-hardening caulking material and the exterior flange screwed down over the caulking material to the wall framing to form a waterproof joint.

That is kind of clear, basically it is saying you must have flashings between two differnt materials (like, say stucco and wood battens) unless it the surface is within 1/4 the width of the eave down from the top of the eave.