This heavy-duty Fire retardant plastic is made from high impact Polyethylene and is used primarily for construction.  The film comes in a natural white color, and has the PolyFlam RCP 500c 01 additive.  

Certification:

Boston Fire Department Cert#57618 

All polyethylene sheeting manufactured for use in construction and agricultural applications is manufactured to meet the minimum physical property requirements as required by ASTM Standard – E154-88 with reference and including ASTM-C168, D828, E84, E96 and E241.