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metal roof pitch transition installation

Posted: Sun Jan 06, 2019 8:43 pm
by john2019
Hi folks, I'm hoping someone can give me advice on my metal roof that seems to be leaking around a pitch transition. One picture shows a view from above the pitch transition; the other shows a view underneath the pitch transition strip/flashing taken from the lower, flatter pitch of roof.

Question 1: I'm wondering if this transition flashing was installed correctly because it sits very high above the ribs on the lower panels - I was thinking it should more or less sit almost on top of the ribs. Is this a problem?

Question 2: If it is acceptable to have this flashing installed in this way, then is the fact that there is a very large opening above each rib a problem? I'm wondering if rain/runoff could be blown in these openings, and if that might be a source of water leakage. Should I seal up these openings above each rib?
IMG_7229 small.jpg
pitch transition flashing
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IMG_7230 smaller.jpg
underneath pitch transition
IMG_7230 smaller.jpg (50.08 KiB) Viewed 200 times
thanks much for your input.


Re: metal roof pitch transition installation

Posted: Sun Jan 06, 2019 9:02 pm
by A. Spruce
I'm not a metal roof guy, and I've never installed a metal roof, AND, I would question an install that leaves gaps on the ribs as your pix show, as well as virtually no overhang of the upper section over the lower section, which could allow wicking of moisture backward at that transition.

During a downpour when there is a lot of flow, no problems. when that downpour passes and you've got drips, back wicking can occur and may account for your problem.

Re: metal roof pitch transition installation

Posted: Mon Jan 07, 2019 9:27 am
by Shannon
Ya you have multiple issues here. The height of that flashing is not really a problem but the fact that it is close to level and has no bend to create a drip is for sure. As Spruce mentioned moisture will want to wick back on the under side easily. Also any driving rain will certainly get through those big gaps around the lower ribs.

Now what can you do? Well first I would seal those gaps around the ribs. Maybe flat tin insert pieces at every rib with the rib profile cut out and then pop rivet to that metal under the flashing each side of the rib. You could then use big stretch caulking to seal the rib to the much better fitting tin inserts?
For the flashing maybe you could pop rivet metal drip edge to the bottom side? You would need a bead of big stretch between the two as you go as well.

Re: metal roof pitch transition installation

Posted: Mon Jan 07, 2019 10:43 am
by john2019
I had the same thought on how to close off the holes. I had not thought of water maybe running back under the flashing but that is certainly possible if there are any places that don't have a clear downward slope. I wish I could horizontally crease that z-channel under the flashing to get it to bend down and lower the overall height - but I think it is too rigid to do that.

Attached is another pic that shows where I think some/most of the water is actually getting in, exacerbated by the lack of downslope on the flashing. It is a lap joint between adjacent pitch flashing pieces. Any input on the best kind of caulk or best way to seal this up in a lasting way?
IMG_7234 - smaller.jpg
IMG_7234 - smaller.jpg (73.97 KiB) Viewed 190 times

Re: metal roof pitch transition installation

Posted: Mon Jan 07, 2019 6:45 pm
by Shannon
Actually even on a decent slope water will run over that edge and some will then migrate backwards under the underside and some may make it to the inside before it drips.