Organisations representing insulation firms (thermal insulation, sound-proofing and acoustic correction, fire-proofing insulation) in the countries of Europe can be FESI member in one of the following categories:

• Active Members: All professional bodies representing insulation firms in every European country can be active members.
• Associate Members: Firms which are members of these professional bodies are associate members, in so far as their professional bodies are active members.
• Corresponding Members: Insulation firms in countries where no representative professional body exists.
• Global informative partners: Global acting companies producing or suppling material or equipment for the insulation contractors, also global organization supporting insulation market