Repairing a Leaking Plumbing Vent

Do you have small water stains appearing on your ceiling?  The problem is likely the flashing around your plumbing vents.

One of the most common, if not the most common problem I find with inspecting roofs, is a leaking flashing boot around the plumbing vent pipe.  When these fail, water gets in to places where it is not supposed to.

There are two varieties of boots available around these parts;  plastic and lead.  The lead ones are the best, because they hold up to the weather much better than the plastic ones.  In fact, unless a critter chews on them, they hardly ever fail before the roof needs to be replaced.  Typically the best roofing contractors will use lead boots.  Do they cost a bit more than the plastic ones?  Yes they do, and  you get what you pay for.

The plastic boots will typically last around 6-8 yrs, depending on their exposure to hot afternoon sun.  They have a rubber collar that grips the side of the pipe as you lower it down.  This creates the seal that keeps the water out.  But after years of baking the sun, the rubber becomes hard and brittle.  It cracks, and gaps form in your now less-than-water-tight seal around the pipe.  You’ve got leaks. No bueno.

I know my flashing boots are leaking, but whatever shall I do?

Damaged Vent Flashing
Here you can see the rubber that seals around the pipe has cracked and failed.

There are two possible solutions.

You can replace the whole flashing boot.  However, to install these correctly, you have to remove the shingles around the vent stack, install the new boot, and install new shingles that will not match.  It creates an unsightly patch around the vent pipe on your roof, and costs a few hundred bucks to get done.

OR, you buy this wonderful little gadget.  I picked mine up on Amazon for about $5.00 bucks. Oatey 3″ Rain Collar.

Be sure to order the one that fits the diameter of your pipe.  It is NOT a one size fits all piece.  If your house has a PVC vent (like in the picture below), it’s more than likely 3″.

Plumbing Vent Flashing Repair
The new collar simply slips over the lip of the vent pipe. Done.

Installation is easy-peasy.

To install the new collar, simply slip it down over the pipe, and seat it against the old cracked rubber. That’s it.  You’re done.  It took me 5x as long to get my ladder out and climb up to the pipe than it did to install the thing.  Even if you aren’t comfortable walking on the roof, a handyman shouldn’t be much more than an hours labor to do this.

Vent Flashing boot
Here is the new seal installed and the leak stopped.

The new collar should last a good while.  Long enough that by the time it wears out, you’ll likely be thinking about a new roof.  If not, and you have super shingles that don’t wear out, you can always slip the old collar off and put a new one on.

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