Advice on corrugated plastic roofing for coop

[Qwerty3159]

This is actually a roof on a pigeon loft but, close enough right?

So when I originally built this because the coop is 4 ft wide I made the roof exactly 4 feet as well to save material on the plastic sheeting (which comes in 8 foot sections) or else I’d be wasting like 40% of each sheet if I made it wider. Then I realized the roof wasn’t long enough to shed water properly so I attached that other strip a couple inches wide to the front. I’ve always had a bit of a leak problem with it but normally only a little bit of water during the heaviest rain, nothing I couldn’t handle.
Now it’s getting significantly worse and I’m looking for advice on patching these leaks without replacing the whole darn thing. You can see in the pictures the algae denotes where water is lingering/seeping through as well as my past attempts to caulk the small gap. I’m sure water is getting in through the rusted screw and washer as well.

 

[Knobby]

I can't tell by the pics, but are you overlapping at the peak or at the ridge? I would overlap it in a way that the waterflow doesn't get under the shorter piece and into the coop..use silicone chalk between the pieces and they sell the corrugating screws with the rubberized washers.

 

[mowin]

I'm going to guess that the water is backing up when the end of the panel is full of leaves and pine needles. I'd remove the end panel, clean both surfaces well, then use silicone and re attach with screws and rubber washers.

 

[raingarden]

The panel at the roof peak should be on top so water is shed instead of running under. If they are overlapped correcty you will not need sealant.

 

[mowin]

The panel at the roof peak should be on top so water is shed instead of running under. If they are overlapped correcty you will not need sealant.

Unless one let's pine needles and leaves to build up acting as a dam.

 

[saysfaa]

... You can see in the pictures the algae denotes where water is lingering/seeping through as well as my past attempts to caulk the small gap. I’m sure water is getting in through the rusted screw and washer as well.

The directions for many corrugated roof panels have the fasteners on the ridges rather than the valleys. You may be able to take the panels off and flip them upside down so you can reattach them that way without putting new holes in it. If you still know the name of the product, you can probably look up whether this should be installed the same way.

It might solve all making it easier for any water that does get under a panel to flow out. Possibly air can get under the tiles more easily, too, to dry it out faster - I'm not sure it will or that it would be worth whatever disadvantage it has.