As an alternative to halogen-containing (e.g. TCPP, brominated polyether polyols) polyurethane foams, we offer flame-retardant foam systems with fire classification class E (=normally flammable according to DIN EN 13501-1) or insulation systems (behind metallic cover layers) with fire classification class B-s2, d0 (=flame-retardant according to DIN EN 13501-1).