The Flash and Batt insulation system is when Closed-cell spray foam and Fiberglass are both used to insulate a space. This system involves a layer of Closed-cell spray foam sprayed and then overlapped by a layer of Fiberglass insulation. This is an effective system that is better than just Fiberglass and less expensive than all Closed-cell spray foam.
One common problem that could occur after the Flash and Batt insulation system is installed is the chance of condensation building up between the layers of the different insulation materials. Condensation develops if the Closed-cell spray foam layer is too thin. When this layer is too thin it does not provide any insulation capabilities which is why it allows condensation to develop when the dew point is reached. If the problem is not taken care of right away, than the homeowner risks mildew and mold developing.
How to Avoid Condensation