A device is for a helicopter deck comprising a supporting, fluid-tight floor. The helicopter deck comprises an overlying, draining top cover formed out of at least two top-cover sections arranged side by side. Each of the top-cover sections comprise a surface portion provided with several drain openings and at least one channel wall projecting downwards, provided with a foot portion which is arranged to be positioned on the surface of the floor. At least one drain channel is defined by the top cover, the floor and two adjacent channel walls. The drain channel is provided with a mouth portion which is connected to a collecting channel. Fluid-transport paths are formed through the at least one drain channel between the drain openings and a drain in the collecting channel. The top-cover sections are detachable from the floor and adjacent top-cover sections.