In Indiana is polystyrene foam insulation permitted to be applied directly to the roof deck without an intervening thermal barrier?

Answer

The direct to deck application is considered an alternative method or material and is regulated
by 675 IAC 12-6-11 on page 36.If the application is the sole subject of an evaluation report "published by an independent, nationally recognized testing laboratory" that "contains limitations, conditions, or standards for alternative materials, method of construction, or design procedures", the State Building Commissioner and State Fire Marshal may approve the use of the application. The application for construction design release must include the evaluation report for the application being requested.