Repairing roof leak from bathroom vent


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Old 01-17-15, 10:08 AM
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Repairing roof leak from bathroom vent

Here's a picture of the leak from the bottom:

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You can see (red arrow) that there's water intrusion. In the house, it's a slow drip when it rains outside, coming down through a drywall nail. Here's what it looks on top of my flat roof:

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I suspect the areas I highlighted in red, but in reality, I have no idea. I didn't see anything obvious like gaps between shingles/etc. What should I be looking for, what's my next step, and how do I repair? Thanks!
 
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Old 01-17-15, 02:40 PM
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It's worth a try to caulk the two sections marked by the red arrows.
 
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Old 01-17-15, 03:31 PM
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Caulking is not the correct method. Trowel on roof cement. But ideally it needs to be properly flashed and sealed. Then use liberal amount of roof cement.
 
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Old 01-17-15, 03:59 PM
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Your profile doesn't tell us what climate zone you are in. I would assume snow and ice are not an issue where you are. If it is just rain and that is a rolled roof I would be inclined to pull the top off of the vent and slide a new flashing down over it, sealing it to the surface of the roof with the roof cement as Norm mentioned. Although I have never worked with a float roof I have to assume they have new flashing and or boots for that purpose. If my suggestion is a hack job the others will enjoy smoking me out.

Bud
 
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Old 01-17-15, 08:10 PM
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If you do a search for "Large Pipe Retrofit Flashing Boots," you'll find several types of flexible flashings that can be installed without removing the cap from the pipe. They work like a charm, with a nifty tongue-and-groove clamp connection, and will keep all water out if installed properly.
 
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Old 01-19-15, 09:14 AM
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OK, I actually went to take the cap off the vent, and realized... this isn't the right vent.. I had my wife tap-tap-tap to figure out which one it was, and it was the furnace vent next to it:

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Does the rust indicate water intrusion? If so, what needs to be replaced/repaired?
 
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Old 01-19-15, 09:20 AM
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Can you remove the cap and inspect the flue? The rust was likely caused by moisture but water entering at that point isn't likely to show up as a leak in the attic or ceiling unless the flue pipe has a hole in it. As far as the cap goes, I'd just wire brush it, apply a rust inhibitive primer and some paint.
 
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Old 01-19-15, 05:56 PM
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I'm a noob - how do I remove the cap? It looks cemented in..just cut it with a razor? I used a flashlight to get a picture of the inside, it looks like the rim is pretty rusted out (red arrow) and there are a few small holes on the inside (circled in blue), too:

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Don't know what it's like further down the flue. Does this look like it might cause the damage in the first pic? Next step?
 
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Old 01-20-15, 03:40 AM
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I don't know how your cap is installed. Some have screws that you'd remove but it could be pop riveted in place or press fitted maybe with some sealant.

Surface rust isn't a big deal but heavy rust might indicate a perforation in the metal. The hole that you circled doesn't look like a rust hole .... could have gotten damaged on installation ?? A little bit of caulking smeared in/around the hole should seal it up. I wonder if you took a flashlight and mirror if you could get a decent look at the inside of the metal flue.
 
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Old 01-20-15, 10:55 AM
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I think that type with the groove you just turn it counter clock wise an inch or two then it should slide off pulling straight up. Might take a little back and forth action to get it loose.


 
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Old 01-24-15, 01:30 AM
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get a gal of herculiner ( eBay - $100-$110 ) & apply it - you'll have no trouble,,, when its time to re-do the roof, put a new vent stack on 1 of our divisions is roofing - to me, its amazing what some of the new materials will do - even flat roofs w/spray-on new coatings
 
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Old 01-24-15, 09:44 AM
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Herculiner, like Rhino, is a sticky goo that's made for lining truck beds. Before spending $100 for a can of it, you might want to check with the manufacturer for performance limitations on a hot roof, before buying it (where summertime temperatures in excess of 100 degrees F. are the norm). There are many other products out there that will work as well or better, and cost a lot less.
 
 

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