# Transition flashing



## carpdad (Oct 11, 2010)

Zero experience with metal roofing but curious. Looks like rake edge flashing is provided with a channel that goes under the trim. Makes sense that these things are already thought of. If channel, gaps shouldn't matter.


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## oggy bleacher (May 3, 2011)

nice. you found a video I had not seen and I watched A LOT of videos on this subject and none of them show the overlapping of the side of the rake trim. This one shows two important details the manual doesn't explain. These panels look similar to the panel I am using. ASC brand doesn't necessarily use the perimeter cleats and offset cleats so that's a big difference.

I like the cleat method but I also suspect it's less forgiving of mistakes so I chose the less complicated brand. I completely grasp how the ASC panels are assembled, while the addition of cleats involves a lot more precision and experience and I started to doubt I could pull it off. Cleats are a superior method since it eliminates foam closures and is really waterproof. But it requires experience.


















All these manuals manage to avoid the single detail of where the rake trim meets at the pitch transition.

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This is a similar standing seam panel with the lower rake trim installed UNDER the transition flashing. This is probably similar to how I will approach it except I will extend the transition flashing long so I can turn the transition flashing down over the pitch break. Otherwise that void will be hard to cover with only the upper rake trim. This brand also uses perimeter cleats for the rake trim.




See how the end of the panel at the rake is turned up 1'' so, there is a cavity under the rake trim but the water is still trapped in a downward slope. Then see how the white transition flashing (they probably used white so it would contrast the green and show up better in the demonstration) has the end turned DOWN one inch or more? That's a key detail the manual doesn't show.



This photo shows one approach I will use if the rake trim is similar. I think it all depends if the profile of the rake trim is low then it can fit _under _the transition flashing, but if the profile is high like in this photo then the lower rake trim is installed OVER the transition flashing. Then the two pieces of rake trim can come together with the upper trim overlapping the lower trim. There might be a way to get fancy with the point of contact with the two rake trim, cutting the top piece so the lower leg extends a little further beyond the overlap, also leaving a tab of horizontal metal that can overlap the top of the lower









These panels move with the heat and that edge will scrape through the lower trim surface eventually.


It's a tricky location. This video helps a lot. thanks.

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This looks like the lower rake trim fits under the transition flashing and then the upper rake trim is cut as long as the transition so the seam between the two rake trim pieces is lower than the crease in the pitch break.


I think the key is to turn the edge of the transition flashing down so there is no exposed gap at the pitch break.

an ASC panel associate had this to say: "Thank you for reaching out to ASC Building Products. Yes, you are correct, as the rake flashing is trimmed and bent to coincide with the roof transition, it will create a gap along the rake edge. We unfortunately do not have any details that currently exist to show how to manage this condition. It will require an additional piece of flashing (or perhaps two) tucked within the gap. The important thing to remember is to shingle, or layer, the material to assist in shedding water off the trims.

Best regards,"

AFTER I SENT PHOTOS THE REP HAD THIS TO ADD:

"Out of the two examples you showed, the silver roof is the proper installation method. As noted previously, we unfortunately don’t have any details on file for this roof condition. The best way to visualize it is that the upper slope and lower slope are treated as two different roofs. The upper slope terminates onto the transition flashing, then the transition flashing acts almost like a ridge cap condition for the lower slope.

In the other picture (green roof), the rake flashing is left with a gap at the transition which will allow water entry."


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## carpdad (Oct 11, 2010)

Sorry too much detail. I think i can assume that as long as there is some kind of turned up edge along the roofing, trim doesn't matter much. One thing i do with shingles is bend the weather barrier (tarpaper or ice shield) over the deck edge to the facia frame. I think the gap can be not so much an eye sore by adding a little piece of the roofing where gap is expected which will be overlapped by the upper trim. Or color matched caulk. It looks like trim is just a trim and not a flashing so finishing detail does not have to be water tight or a drainage plane.
Found another video where the rake edge is bent but not as much as above video. Same as formed edge of one piece flashing that sometimes is used instead of step flashings. I think i would prefer as much channel as the trim will allow.


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## oggy bleacher (May 3, 2011)

I got a plan. I will document for the future. The manuals are kind of misleading since they show the transition flashing installed with no rake trim. Like I should install the upper and lower panels and then the rake trim but with ASC brand the lower rake trim will be installed prior to transition flashing. Other brands are different. The diagrams are just a cross section with the rake trim invisible. Didnt want to make it too easy to understand or people like me would get the crazy idea they can DIY a metal roof.


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