Ridge or Static Vents on Multi-level Hip Roof
"since the builder used edge/joining clips" - it is H-clipped (not that I could do anything about it now, if it wasn't), thus marginally meeting code.
The ridge vent, if I go that route, will be shingle-over. But because the sheathing is so thin, what I've seen here & elsewhere indicates I might be wise to go with screws to actually attach the ridge vent because the thin sheathing doesn't give enough contact thickness with nails. So the question then becomes what style head (wood/deck/sheetrock-style, or pan-head) on the screws, so as not to cause problems with the ridge cap?