Numerous longstanding government facilities are spread out across the 49th State. Hundreds of built-up roofs (BUR) continue to perform and provide protection from the extreme weather of Alaska. 
Most Army and Air-force structures were constructed with flat concrete roof decks. For forty years tapered EPS roof insulation has been effectively set into a flood coat of cooling asphalt which also works as a vapor retarder.
Alaska roofing contractors are skilled in setting the EPS when the asphalt cools to between 200 and 250 degrees Fahrenheit.
The cover board joints are taped as protection from the hot asphalt above as the membrane layers are applied.
PIMA states that “Polyisocyanurate insulation is used in 70% of commercial roofs”-(except for Alaska). On the other hand EPS roof insulation can be found installed in 70% of commercial roofs throughout Alaska. One of the best kept secrets in roofing!