An apparatus for providing a coating to a surface of a substrate, the apparatus comprising: - at least one ALD-coating unit in which the surface of the substrate is subjected to successive surface reactions of at least a first precursor and a second precursor according to principles of atomic layer deposition for coating the surface (1 a) of the substrate; - a first reel for unwinding the substrate to be coated; - a second reel for rewinding the coated substrate; - one or more primary support structures provided on the same side of the substrate as the surface to be coated or the coated surface for forming a substrate transport path from the first reel through the at least one primary support structure to the second reel; - an interleave web in connection with each of the one or more primary support structures, said interleave web is arranged to protect the surface to be coated or the coated surface when the substrate is passing through the one or more primary support structures, said interleave web is arranged to move together with the substrate along at least part of the substrate transport path, the interleave web is arranged between each of the one or more primary support structures and the surface to be coated or the coated surface such that the surface to be coated or the coated surface is arranged to contact only with the interleave web along the substrate transport path from the first reel to the second reel; - one or more secondary interleave unwinding reels comprising the interleave web for unwinding the interleave web, said one or more secondary interleave unwinding reels are arranged such that the interleave web is brought together with the substrate after the coating unit and before or at the first primary support structure after the coating unit, the second reel is arranged to rewind both the coated substrate and the interleave web. - at least one ALD-coating unit in which the surface of the substrate is subjected to successive surface reactions of at least a first precursor and a second precursor according to principles of atomic layer deposition for coating the surface (1 a) of the substrate; - a first reel for unwinding the substrate to be coated; - a second reel for rewinding the coated substrate; - one or more primary support structures provided on the same side of the substrate as the surface to be coated or the coated surface for forming a substrate transport path from the first reel through the at least one primary support structure to the second reel; - an interleave web in connection with each of the one or more primary support structures, said interleave web is arranged to protect the surface to be coated or the coated surface when the substrate is passing through the one or more primary support structures, said interleave web is arranged to move together with the substrate along at least part of the substrate transport path, the interleave web is arranged between each of the one or more primary support structures and the surface to be coated or the coated surface such that the surface to be coated or the coated surface is arranged to contact only with the interleave web along the substrate transport path from the first reel to the second reel; - one or more secondary interleave unwinding reels comprising the interleave web for unwinding the interleave web, said one or more secondary interleave unwinding reels are arranged such that the interleave web is brought together with the substrate after the coating unit and before or at the first primary support structure after the coating unit, the second reel is arranged to rewind both the coated substrate and the interleave web.