What is class “A” Fire rating?

As per ASTM E84 standards fire properties of building material are categorized based on SMOKE DEVELOPMENT, FIRE SPREAD properties of that particular material. EPS fire properties rated as CLASS A or CLASS 1 as its fire properties complies with in the specified range of CLASS A or 1

• EPS Smoke development index ( SDI): 200  As per ASTM E84 (450 as Max)
• EPS Flame Spread Index (FSI) :  10  (Class A) As per ASTM E84 ( 0-25 as Max)