The 1x slats,w appropriate gaps but w/o solid sheathing, are commonally used
in wet climates like the Pacific northwest of the US. This lets air
circulate better in and around wood shakes & shinges to promote quicker
drying for longer life. Keeping them damp promotes mildew growth. Here in
the US southwest, wood shakes (we don't see many wood shingles) are applied
directly over sheathing like your OSB since moisture is not a problem.

"ezalpha" wrote in message
.. .
Can I install cedar shingles directly on the 7/16" OSB plywood sheathing
on