It would be nice if vent flashing would last as long as the actual roof did. Unfortunately many of us aren’t this lucky and the flashing will need to be replaced at some point. If you take your time and use proper safety precautions, this is something that can be done on your own in just a day.
You’ll need to start by gathering all the necessary supplies. It’s important to get the exact type of flashing needed for the job. You may need to climb the roof to look at it before you go shopping for it.
Climb up on the roof and remove the shingles just around the vent. You can do this by using your pry bar gently enough to avoid damaging the shingles. It’s pretty common to damage them even when you are gentle, so make sure you have some extra shingles on hand just in case a few do break.
Use the pry bar underneath the flashing, use the scrap wood as a lever to get the flashing pryed up. You should be careful with this as well so you don’t damage the vent pipe.
Gently pull the flashing so it comes off over the vent pipe. If you don’t take your time with this you can knock the vent pipe out. That will be a bigger repair job than it’s worth, so just try to avoid this all together. If there are nails left on the roof in this area you need to go ahead and pull these. You can fill the holes from the nails with the asphalt cement and your trowel.
Put the new flashing in place. Make sure you align the collar to look the same direction as the old one did. Use your roofing nails to secure the flashing into place around the vent pipe.
Cover the exposed nail heads with the asphalt cement. You also want to apply the cement all around the collar. This will seal it to the roof and will lessen the chance of leaks forming later on.
Starting with the bottom row and working up replace your shingles. Take your time with this to ensure even placement. You don’t want the shingles to end up looking out of place. The exposed nail heads should be covered with asphalt cement.
If you’ve followed the directions you should have new flashing that won’t leak through your roof now. Vent flashing is an important aspect of your roof. It’s a good idea to check it periodically and install new flashing if you ever find a problem. Do this before it starts to leak to avoid major damage, or pots in your living room collecting drip water. Be sure that shingles overlap the flashing.