Many RE text books have exploded views of a house, showing the parts from the vapor barrier at a foundation up to the overlap of shingles, the ridge cap at the top of a roof.

He made me tear off every bit of my new coquina just so he could see that i had used vapor barrier over the new wood and that it was really only 2 boards replaced.

I can't tell you how many I've had to repair dry rot in because there was no vapor barrier.

If so, the ridge may very well be the culprit... either because it is sealed so tightly (not uncommon with SIPS panels) that all the vapor collects at the ridge area with no place to go.  

We even installed additional insulation and a vapor barrier to prevent further moisture damage. 

Alternatively he suggested adding dirt to level out the space and then installing vapor barrier for $800.Anybody had experience with this before?  

From there we led the water out of the crawler, then we put a nice thick vapor barrier throughout the entire crawler and sealed it.

I see the tile in the basement unit, is that installed on the slab or against a good vapor barrier? 

These rolls can be purchased in various densities to accomplish higher R-Values, even for cavities of the same thickness.As for what's best or most efficient - questions without absolute answers in my opinion... find out what the pros do in your area - that'll be a good indicator.Also, given your locale, you may be required to have a vapor barrier, so be sure to check into that.Good luck!

We decided to have a vapor barrier installed along with a sump pump in this area which cost about $4600.