A roof structure (1) for a greenhouse comprises a fixed roof (2) including a roof opening (3) and a ventilation window (4) which is movable with respect to the fixed roof (2) between a closed position in which the ventilation window (4) closes off the roof opening (3), and a vent position in which a window opening (11) is present such that an air channel is formed between the roof opening (3) and the ambient. The roof structure (1) is provided with a vent limiter (7) having a ventilation opening (8) which is smaller than the window opening (11), wherein the air channel extends through the ventilation opening (8).
