Leaky garage roof

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  #1  
Old 06-05-20, 04:06 PM
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Leaky garage roof

So I have a leak in my garage roof. It's 6 years old and it started leaking through the middle of the ceiling. I had a roofer come out to inspect it and he couldn't find any obvious leaks from the top, but he put some extra caulking down on a couple of places that looked like they were starting to wear out.

It leaked again, so I went to the effort of pulling down a big chunk of the ceiling.

So first issue is apparently some mice have chewed the vapour barrier up like crazy. The insulation was still wet 5 days after the last rain (and it's been 30 degrees C most days sine). The main spot where the water was coming down was directly beneath one of the two roof vents (which had been inspected), then traveling along the vapour barrier until it found a hole.

So I plan to replace all of the insulation with green Roxul and repair what I can get at of the vapour barrier. As for the leak though... it just rained, without any particularly strong winds, and I can see the BOTTOM of the vent cap is splattered with water, so obviously it's just coming in like that. I can't yet quite see if the other vent is having the same problem, but there has been no water leakage near it as far as I have noticed.

Any ideas?

The flash went funny in the picture so you can't see the water drops. And yes I know it's not supposed to be over a rafter, I didn't do it, and I'm not really sure what I could possibly do about that now...

Thanks for any help/advice anyone might have!
 
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Last edited by Radagast; 06-05-20 at 04:10 PM. Reason: Fixed the picture
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Old 06-05-20, 04:13 PM
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If its leaking around the vent (assuming that's what that dark black box is) we would need a photo of the outside if the vent, not the inside.

Fixing a leaking vent isnt rocket scientist e but caulk isnt usually the answer. If its leaking it was likely installed improperly. I dont know that I have ever had a roof vent leak.
 
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Old 06-05-20, 04:16 PM
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It seems, based on where I saw the water droplets, that it's leaking THROUGH the vent not around it. I will try to get a picture from outside, but I'm not great with heights and you can't really see this area well from the house.
 
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Old 06-05-20, 04:41 PM
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Here's a better picture of the inside of the vent. And the closest I could get for the roof vent - my ladder isn't tall enough to get me on the roof, this was actually me holding my phone as high over my head as I could, and the roof overhangs to 6" from the property line fence along the side so I can't get closer that way either.

The warped bottom doesn't look great but it's definitely not leaking from there (or at least, that's not the primary leak).
 
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Old 06-06-20, 06:24 AM
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Not thrilled with the way they ran the shingles at the bottom of that vent.
The way it was done the fastners are right about where the glue line is, there should have been a shingle ran under that area.
Also as you can see by using a plastic vent instead of metal it buckeled up.
 
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Old 06-06-20, 06:36 AM
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Thats what I expected to see. Anytime you have 3 rows of shingles on the side of a vent it has the potential to leak. Roofers do that because they think it looks better, but its sure to leak someday. Water above the vent can get under the shingles and it eventually leaks in. That water dams up and runs sideways along the top edge of that 3rd (bottom) shingle. The 3rd (bottom) shingle should have been under the vent flange to help flash it. Then it is less likely to leak because the top edge of that 3rd (bottom) shingle is above the cutout for your vent hole. Any water that runs off the side of the vent flange is on top of a shingle... not on your tar paper.

Plus those plastic vents are junk. They don't usually have a ridge on the flange to stop water from just going under the edges. And the plastic obviously doesn't lay flat along the edges like a metal one would. (All the edges are likely wavy like that, it's just that is the only one you can see) I'd replace it with a lomanco 750 and make sure that 3rd row is under the flange next time.
 
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Old 06-06-20, 08:27 AM
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So what you mean is that the bottom row of shingles should run under the bottom portion of the vent, instead of it sitting right on the sheathing? Here's a picture of what it looked like when they were installing it.

How hard of a job is it to replace the vents? Should I get a roofer to do it or borrow my brother who is handy and not afraid of heights?

This is what you mean? https://www.homehardwarecenter.com/2...ct/lomanco-750

 
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Old 06-06-20, 09:05 AM
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The following should explain it.
Interesting part is around the 7:45 mark.

https://www.youtube.com/watch?v=L2nNTfcPmeg
 
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Old 06-06-20, 10:23 AM
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Number one... where is the felt paper underlayment in that photo...

...and I would be applying 1 or 2 more rows of shingles... then cut the hole. Then place the vent.

Ideally you have about 2" of shingle laid above the hole that is cut, then you lay the vent, then you shingle around it. No caulk required.

In that video, intentionally creating a seam on either side of the top of the vent is (imo) stupid and unnecessary. It creates a potential leak point. You cut out a full shingle to lay over the top of any vent so that water cannot leak down the seam.
 
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