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Flashing not protecting corrugated roof


stonesif's Avatar
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10-06-17, 06:49 PM   #1 (permalink)  
Flashing not protecting corrugated roof

I'll show some pictures of my situation before I proceed:

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I have a corrugated plastic roof over my back porch, which has started leaking. From what I can tell, it looks like the flashing no longer has a grade to it, and is instead collecting water. I believe the water is then slowly trickling under the flashing as it fills up, and then dripping behind the corrugated roof.

Ideas I've had are to extend the flashing (are there extensions available?) or replace it with longer flashing (a pain, as it's behind the siding). Or, place something else on top which would protect these seams. Lastly, I could try putting sealant at the top of the corrugated roof, but underneath the flashing. Do you have any ideas or recommendations? Thank you!


Last edited by PJmax; 10-06-17 at 07:35 PM. Reason: added pics from link
 
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10-06-17, 06:55 PM   #2 (permalink)  
There are plenty of places your vinyl siding could be leaking, and if water gets behind the siding, it gets behind the flashing too. With no idea exactly where it's leaking it would be hard to suggest where to look.

 
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10-06-17, 07:14 PM   #3 (permalink)  
Thanks, but I'm not worried about the vinyl siding leaking; that's doing fine. There's water dripping along the corrugated roof, which is caused by water pooling on the flashing.

 
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10-06-17, 07:36 PM   #4 (permalink)  
I want to know how you are going to get out there to make any type of repair.


~ Pete ~

 
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10-06-17, 08:13 PM   #5 (permalink)  
If you want help you are going to need to be more specific. Is it leaking into the room at one spot, such as at the seam between two pieces of flashing? Or in the corner, or ALL ALONG the corregated roof, or what? Maybe more photos from inside, or at least a better description would help. Some people annotate their pictures by drawing on them.

And by your comment about the siding, I can tell you are too quick to discount other possible sources for the leak. Water gets behind vinyl siding at every window opening, for example... so if the leak is directly below the windows, you should at least consider that possibility. And wall flashings like that are rarely detailed behind the wrb correctly to prevent a leak from above. You are getting advice from experienced people here, don't be so quick to dismiss it.

Also, I see no downspouts coming off your gutter on the roof up above... that's a long run with no downspouts... have you checked if those gutters are plugged and might be spilling a lot of water unecessarily onto your correlated roof?

PJ's comment is funny, but true... unless you lay sheets of plywood up there to distribute your weight you will probably have bigger problems.

And unless I'm mistaken, water can't mysteriously penetrate a metal flashing (unless it's doing so at a seam)... so water pooling "on the flashing" is not the issue here. Getting behind it from the siding/windows above... or getting under the front of it, maybe. If the latter, maybe the foam closure (under the roofing) is old and cracked, or is brittle, no longer sealed. The low slope doesn't help.

 
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10-07-17, 04:29 AM   #6 (permalink)  
In the picture with your hand in it, has the panel after your hand been replaced recently? And is that where it's leaking? The picture doesn't show it well, but it looks like that panel is newer and cleaner than the rest.... and it doesn't completely cover the foam closure on top, therefore would not seal very well. The cut on top also doesn't look square at ALL, it trails down the farther away you go. And I imagine if the top edge isn't sealed well that might be the first place it would want to leak. Or perhaps all the others were sealed to the gasket with silicone and the one that was replaced was not... Won't know unless you are more specific about the location of the leak though.

If it never leaked until that panel was replaced, that would be a safe bet.

If water is dripping out inside between those two "header 2x4's", that could be blamed on a stupid design. I don't see how that WOULDN'T leak if it ever got wet above the panels. Unsure why the panels wouldn't be about 2" longer to go under the flashing farther.

 
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10-07-17, 07:32 AM   #7 (permalink)  
It looks like it may be leaking around that hold down screw as it's rusty.

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10-07-17, 11:23 AM   #8 (permalink)  
PJ, I was wondering about that too. Was hoping a large piece of plywood would help distribute the weight. Think that'll be enough?

Here are some new pictures: https://photos.app.goo.gl/sZwRMjuccRos1fqy1

Sleeper, thanks for all the ideas, and I'll do my best to get to everything. And I'll make sure not to discount ideas; thanks for pointing that out. In the porch (with the corrugated roof), we found water dripping from the plastic corrugated roof. In the inside closeup, you'll see arrows pointing to where water has been dripping in. We've looked at this very closely, and water does not appear to be coming from any holes or places where the sheets of plastic overlap. It appears to be directly related to where the flashing is.

If you look at the exterior pictures, the only section of the corrugated roof that's leaking is the 1/3rd on the right (under the two windows). This is where the flashing is. The left 2/3rds has the plastic roof tucked underneath the main roof, and we have had zero problems here.

There is no gutter on the roof above. There is a seam on the flashing, but the water is spreading far beyond where that seam is. The low slope is not helping one bit. The panel has not been replaced to my knowledge. It was likely installed when the porch was built, but I have not done anything with it since I purchased the house a year ago.

 
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10-07-17, 11:53 AM   #9 (permalink)  
(under the two windows).
That's exactly why I mentioned the possibility of water getting behind the siding. It does this at windows, and only the brightest of installers understand how and why.

Windows generally get installed on top of a wrb (housewrap). So does the siding, and so does the flashing. When water runs down the wall and comes to a window surrounded by vinyl siding, some of that water gets behind the siding. It normally drains out once it reaches the bottom of the WRB. But, if the flashing is also on top of the WRB (and not behind it) then water goes behind the flashing and leaks in.

If that is where the leak is coming from, it would be fairly easy to fix. But you would need to put a few sheets of plywood on top of the roof framing... and remove some siding (you would need a Malco Sideswiper tool to remove and reattach the siding). If you find that the flashing IS on top of the WRB, you could simply seal the flashing to the WRB with flashing tape, such as Protectowrap.

You could probably cut the amount of water hitting that area by 10x if you would put gutters on the upper roof. That's a lot of water pouring off one roof onto one spot on another, where it is prone to splash back.

 
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