the strip includes an elongated body having a pair of parallel sidewalls , an upper surface between sidewalls and a lower surface between sidewalls adapted to engage a water barrier on a wood roof . a plurality of spaced , inverted channels are formed along the body from the lower surface and terminate generally midway between the upper and lower surfaces . the channels extend between the body sidewalls and provide drainage perpendicular to the length of the body . the upper surface may be planar or be stepped . a plurality of spaced recesses with preset fasteners are disposed along the upper body surface .