Leaky roof vent boot.....what should I do, what should I do

[MikeT]

One of the (few) advantages of being a weekend warrior is that I can see the results of work completed and notice any flaws.  This weekend, we noticed that we had a very minor drip coming from the seal on the roof vent boot (2") where the vent pipe penetrates the roof.   Can I just put blackjack on around the area where the pipe and the boot meet?  Other fixes to consider....

[bayview]

   Is it leaking where the pipe penetrates the boot or do you have a problem where the vent overlaps the shingles.
   
   First, I would make sure the shingles are installed properly . . .

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[MikeT]

It is almost certainly coming from the area where the boot meets the pipe.  I traced the small drip line to up the pipe.  If the leak were coming from the shingle overlap, the leak would be coming from a different place.

[DirtyLittleSecret]

black rtv

[Redoverfarm]

The boot should be tucked under the shingle above the boot and the ridge and left over the lower shingle to the eve.  Did you have to cut the boot to fit your vent pipe.  Some are multiple size boots and if you just mistakenly cut a nick it will leak with water running down the vent pipe.  I usually cut mine a little undersize and use lubricant to make it slip over and seal tighter.  If it is a metal roof boot then maybe not enough sealent was applied under the lip of the boot on the uphill side. 

[MikeT]

The boot is an all rubber one.  I didn't do the install on that one, so I cannot tell you.  It is on the backside of the house on the other side of the gable.  I am almost certain that the seal where the pipe penetrates the boot has a nick or something.  I was thinking that I could hit it with some Blackjack or similar product.  But I could also take another boot, cut off the part that goes under the shingles and set it on top of the other one. 

mt

[Redoverfarm]

Mike I don't think the cement would be a long term fix.  If it were mine I would replace the boot.  If it is shingle it is no big deal to just carefully pull up the shingle and remove the boot and replace and re-install the shingle.  They might have nailed the boot down so take a small flat pry to remove the nails.  If you cut the old boot off there is a possibilty that any water will then leak under the new boot and over the old portion.