A new non-halogenated polyiso insulation board that's better for the environment, since it does not contain potentially hazardous halogenated flame-retardant chemicals. EnergyGuard™ NH HD Polyiso Roof Insulation meets all the inherent properties and performance polyiso is known for and has the highest R-value (2.5) of any cover board without any halogenated flame retardants – making it your best choice for a sustainable building design.