I am working on a ComCheck for a metal structure that will be used as a shop/warehouse.
Purlins are 6″ deep and I’m looking for an insulation strategy that may or may not include outboard insulation pre-screw down roof, not standing seam.

Any recommendations on a best practice assembly?  It’s clear a thermal break is vital either topside or below.  

We were considering a few inches (2 or 3) of high density foam straight to the underside of the roof system, then fill with batts and cross batt below purlins for thermal break.

I’m concerned about contact of batt insulation at the finished ceiling, and if we’ve created a dew point at the top side of the ceiling finish if there is not continuous contact.  The builder wants the corrugated roof to be the ceiling finish and I can imagine condensation running down the ceiling to the outside walls.

Thanks very much
Andy