My greenhouses are very typical aluminium-framed, with the ridges being complicated aluminium extrusions which includes C-shaped (female) sections which act as the hinges for the roof vents, which have corresponding (male) profiles which slide into the C-shaped part of the ridge bar.
Anyone who has erected an aluminium greenhouse will follow that (hopefully).
The very top of the vents have started leaking, which, with all the recent rain, means quite a wet floor inside the greenhouse.
The inner part of the ridge bar forms a flange to which the roof bars are attached, and the water is dripping from that on one side of each roof vent.
I have had things apart and cleared build-up of moss/lichen and even worked the vents a few inches eaither way along the ridge bar, back to front of the greenhouse, but it still leaks.
How, where is the water making its way in? Why? Cure? (It should not need caulk, it was water-tight for way over ten years without any.)