Leaking shed roof at transition from garage

Thats a great point. I need to look into those and measure the profile of mine. I know I will need to replace the existing ones - half them are shot

 

Thank you everyone for the suggestions. I ended up doing it the hardest possible way I could think of (but also the cheapest way)

50 ft roll of 10" aluminum flashing. Used some 2x4s as a guide and bent a continuous 29 ft piece. 3.5" up and 6.5" down over the corrugated tin - with a bend just under 90 degrees to fit my roof line.

I managed to get it installed in one continuous piece - under the existing flashing AND under the existing drip edge that was hidden underneath. Talk about a miserable job to do by yourself in the blazing sun.. Nothing is screwed in place yet - had to knock off early yesterday afternoon due to the heat wave we are in right now. But I got a bunch of scrap 4x4s up there so the wind shouldn't move anything until I can get it screwed in later this week. Also have new closure strips to install at the bottom.

After cutting the old flashing off and looking at the way it was built (multiple layers of flashing with seams next to each other) Im feeling somewhat confident this will be the fix I need. Best part is Im only in it for about $60-70 at this point. Not counting the gallon of roofing tar I scrapped off



Roofing tar scraped off, old flashing cut, and old closure strips peeled off. It cleaned up well.

 

Final product

 

As I tend to over do things I would seal the ends of the roofing pictured below with a polyurethane
flashing sealant. With your new piece it should be well protected -- on the other hand if water ever did make it under there the sealant would stop it.



This is the product, this stuff is tough and won't crack like "tar" products.
Read the label carefully to make sure it is the polyurethane product.

 

Hope to be wrapping up this project later today. Would you guys run a bead of that polyurethane sealant on top of the foam closure strip before screwing the flashing down?

The install guides from Union Corrugating indicate yes - but every video Ive seen of real world installations (other than their own) dont show any sealant used.

I plan on one screw per rib (9 inches) as indicated by them. I have to imagine the will make things very tight - not sure if the sealant will be adding much at that point?

 

I go with the manufacturer recommendation.

 

In addition to that I would put a deeper flashing on the metal roof, get the water that comes off the roof farther away from joint.

$56 Amerimax Aluminum Roll Flashing 0.0078 " 24 " X 10 '

https://www.amazon.com/Amerimax-Alu...-0078/dp/B002YGYBBW?smid=A1T1R9Q3ML5YGI&gQT=1

 

Generally, the closure has one sticky side against the roof. The screws go through the flashing, through the closure, and into the roof. Don't over tighten the screws as it will split the rubber washer and the screws will leak. The screws themselves hold the closure in place.