XFLAM consists of EPS pre-expanded beads with a hybrid phenolic resin, a catalyst, lightweight additives and carbon. The resin has high adhesive bond energy. It is hard to break down under fire energy and eliminates the exposure of the EPS bead to the flame source. At 1200°C Celsius the phenolic honeycomb matrix remains intact and the fire behaviour is limited to charring which significantly delays the fire spread. Combustion is restricted to small cleaning burning cells with very little smoke production and negligible toxic species.

In comparison to other RCPs (rigid cellular plastics) such as PIR (polyisocyanurate) and PUR (polyurethane)  XFLAM provides superior fire resistance. It achieves its FM Approval with simple and cost effective construction details and is the only RCP that achieves a Group 1 BCA classification.