Common sense and laboratory testing say installing window bucks with exterior continuous insulation, such as foam plastic insulating sheathing (FPIS), is unnecessary./There are much better alternatives.
Utilizing airspace to provide an R-value in building assemblies is not straightforward.
Water-resistive barriers (WRB) along with properly integrated flashing, provide a necessary means for building designers to prevent rain-water intrusion, as also known as “bulk water” management.
Recently, the Applied Building Technology Group, LLC (ABTG) analyzed current market knowledge, data, and practices with regard to water vapor retarder methods.
When the building code or technology changes, there can be confusion in the marketplace with regard to the proper use of foam sheathing in the building envelope.