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 (PVA) and - (i) the polymer multilayer structure is obtainable by coextrusion or (ii) in addition to the core layer , also the tiepolymer layers 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 (PVA) and - (i) the polymer multilayer structure is obtainable by coextrusion or (ii) in addition to the core layer , also the tiepolymer layers 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 . <EOS>