A covering suitable for protecting a core of an insulation panel of an external thermal insulation composite system, the covering comprising - a base structure comprising a fibrous non-woven layer, - a polymer multilayer structure joined to the base structure, the polymer multilayer structure comprising • a first tie polymer layer, • a second tie polymer layer, and • a core layer in between the first tie polymer layer and the second tie polymer layer, the core layer ∘ being made of polymer material, ∘ having a specific mass of at least 1 g/m 2, and ∘ being obtainable by casting, extrusion or coextrusion, wherein • the first tie polymer layer, the second tie polymer layer, and the core layer are joined to each other, whereby - the covering comprises a first surface and an opposite second surface, the covering being arranged such that - the fibrous non-woven layer comprises the first surface of the covering, whereby - a rendering can be applied onto the first surface of the covering, - the second surface of the covering can be attached to a core of a thermal insulation element, and - the covering is gas tight at least to some extent, characterized in that - the core layer comprises at least one of ethylene vinyl alcohol (EVOH) and poly vinyl alcohol and - (i) the polymer multilayer structure is obtainable by coextrusion or (ii) in addition to the core layer, also the tiepolymer layers (122, 123) of the polymer multilayer structure are obtainable by casting or extrusion, and - the polymer multilayer structure has a specific weight of at least 20 g/m 2. - a base structure comprising a fibrous non-woven layer, - a polymer multilayer structure joined to the base structure, the polymer multilayer structure comprising • a first tie polymer layer, • a second tie polymer layer, and • a core layer in between the first tie polymer layer and the second tie polymer layer, the core layer ∘ being made of polymer material, ∘ having a specific mass of at least 1 g/m 2, and ∘ being obtainable by casting, extrusion or coextrusion, wherein • the first tie polymer layer, the second tie polymer layer, and the core layer are joined to each other, whereby • a first tie polymer layer, • a second tie polymer layer, and • a core layer in between the first tie polymer layer and the second tie polymer layer, the core layer ∘ being made of polymer material, ∘ having a specific mass of at least 1 g/m 2, and ∘ being obtainable by casting, extrusion or coextrusion, wherein ∘ being made of polymer material, ∘ having a specific mass of at least 1 g/m 2, and ∘ being obtainable by casting, extrusion or coextrusion, wherein • the first tie polymer layer, the second tie polymer layer, and the core layer are joined to each other, whereby - the covering comprises a first surface and an opposite second surface, the covering being arranged such that - the fibrous non-woven layer comprises the first surface of the covering, whereby - a rendering can be applied onto the first surface of the covering, - the second surface of the covering can be attached to a core of a thermal insulation element, and - the covering is gas tight at least to some extent, - the core layer comprises at least one of ethylene vinyl alcohol (EVOH) and poly vinyl alcohol and - (i) the polymer multilayer structure is obtainable by coextrusion or (ii) in addition to the core layer, also the tiepolymer layers (122, 123) of the polymer multilayer structure are obtainable by casting or extrusion, and - the polymer multilayer structure has a specific weight of at least 20 g/m 2.