What is the best method to use for roof top ventilation on an existing concrete tile roof. I already have adequate eave ventilation and need some way for the air to exit.

 

Dont know where they got them. But down here on tile roofs they have like some 4' long metal roofvents that they put on each side of the ridge cap look like the button vents only long.Had one home tile roof worked a power vent fan in it worked real good off a tstat. That way only one more hole is all.

ED

 

The vents ED is referring to are called eyebrow and are the least visually offensive.
The most Ideal placement is between the rafters, because field plywood deflects.
Remove sufficient roofing to place the vent flat on the felt, move the vent down so that it overlaps the roofing on the bottom, until the flashing is in line with the horizontal line described by that row of shingles. Mark the center of the top of the flashing. Move the vent aside and from a point 4"lower than the upper mark, cut an upside down "T" in the felt paper, fold the paper aside and insert the vent under the paper, to its final position and secure in place, reinstall the roofing in the reverse order of the removal.