The use of a polyisocyanurate for manufacturing profiles for fire doors or windows and/or for manufacturing fire doors or windows, characterized in that the profiles for fire doors or windows and/or the fire doors or windows comply with the UNI EN 1634-1 and/or UNI-EN 1364-1 standards, the polyisocyanurate being obtainable by mixing and curing a composition consisting of: a) aromatic polyisocyanates having functionalities higher than or equal to 2,5; b) aromatic polyester polyols having substantially all primary hydroxyl groups, the aromatic polyester polyols having functionalities higher than or equal to 2 and an hydroxyl number of 150 mgKOH / g to 350 mgKOH / g; c) at least one trimerisation catalyst; d) at least one flame retardant agent; e) at least one surfactant agent; f) possibly at least one filler; g) possibly at least one further additive selected from the group consisting of: at least one dehydrating agent, at least one deaerating agent, at least one expanding agent consisting exclusively of water, expanding graphite; wherein the composition is free of chain extender agents and tertiary amine; and wherein the composition has an isocyanate index of 200 to 400, preferably of 300 to 350; and wherein: in case the polyisocyanurate is of the substantially porosity-free compact type with a density higher than 800 kg/m 3 measured in compliance with the EN ISO 845:2006 standard: - the composition is substantially free of air, free of said expanding graphite and free of said expanding agent; and - said at least one further additive consisting of: g1.1) said at least one dehydrating agent; g1.2) said at least one deaerating agent; or in case the polyisocyanurate has a density measured in compliance with the EN ISO 845:2006 standard of 400 kg/m 3 to 800 kg/m 3: - the composition is free of said expanding graphite, said dehydrating agent and said deaerating agent; and - said at least one further additive consisting of: g2.1) said at least one expanding agent in an amount of less than 1 phr of water per 100 phr of polyol, preferably less than 0,5 phr of water per 100 phr of polyol; or in case the polyisocyanurate is of the expanded type with a density measured in compliance with the EN ISO 845:2006 standard comprised between 20 kg/m 3 and 400 kg/m 3, preferably comprised between 100 kg/m 3 and 400 kg/m 3: - the composition is free of said dehydrating agent and said deaerating agent; - said at least one further additive consisting of: g3.1) said expanding graphite; g3.2) said expanding agent. a) aromatic polyisocyanates having functionalities higher than or equal to 2,5; b) aromatic polyester polyols having substantially all primary hydroxyl groups, the aromatic polyester polyols having functionalities higher than or equal to 2 and an hydroxyl number of 150 mgKOH / g to 350 mgKOH / g; c) at least one trimerisation catalyst; d) at least one flame retardant agent; e) at least one surfactant agent; f) possibly at least one filler; g) possibly at least one further additive selected from the group consisting of: at least one dehydrating agent, at least one deaerating agent, at least one expanding agent consisting exclusively of water, expanding graphite; in case the polyisocyanurate is of the substantially porosity-free compact type with a density higher than 800 kg/m 3 measured in compliance with the EN ISO 845:2006 standard: - the composition is substantially free of air, free of said expanding graphite and free of said expanding agent; and - said at least one further additive consisting of: g1.1) said at least one dehydrating agent; g1.2) said at least one deaerating agent; - the composition is substantially free of air, free of said expanding graphite and free of said expanding agent; and - said at least one further additive consisting of: g1.1) said at least one dehydrating agent; g1.2) said at least one deaerating agent; g1.1) said at least one dehydrating agent; g1.2) said at least one deaerating agent; - the composition is free of said expanding graphite, said dehydrating agent and said deaerating agent; and - said at least one further additive consisting of: g2.1) said at least one expanding agent in an amount of less than 1 phr of water per 100 phr of polyol, preferably less than 0,5 phr of water per 100 phr of polyol; g2.1) said at least one expanding agent in an amount of less than 1 phr of water per 100 phr of polyol, preferably less than 0,5 phr of water per 100 phr of polyol; - the composition is free of said dehydrating agent and said deaerating agent; - said at least one further additive consisting of: g3.1) said expanding graphite; g3.2) said expanding agent. g3.1) said expanding graphite; g3.2) said expanding agent.