This repair is continued from Part 1.
Cracked Roof Vent Boot Flashing Repair
I called several roofing companies in my area about the cracked vent boot, but none were available due to the once in 500 year flooding rains that fell on the Atlanta metro area in September. One company said they’d received 600 calls on Monday and most could only put me on a waiting list for a call back. I was quoted $125 to install lead pipe flashing for labor and materials, but no one could promise when they could get to it.
I was able to buy an Oatey Galvanized Base No-Calk® Roof Flashing at Lowes for about $7 that fit a 2″ inch vent pipe. I would have preferred a lead pipe flashing because it’s the best and longest lasting flashing solution that avoids the problem of cracked rubber boots. I can always hire a roofer when they’re not so busy and have lead flashing installed.
Oatey Galvanized Base No-Calk® Roof Flashing
Roof Vent Flashing Installation
Removing the old roof vent and installing a new one is simple:
- Pry up the roofing nails used to attach the old flashing.
- Gently lift up the shingles above the flashing.
- Lift the flashing off the vent pipe.
- Slide the new flashing over the vent pipe.
- Tuck the uphill part of the flashing under the shingles.
- Fasten the new flashing with galvanized roofing nails.
- Apply a dab of roofing sealant to the nail heads and bottom tabs of the shingles that were disturbed.
The entire job takes less than 15 minutes. It seems easy and it is, unless you have a high and steep roof like mine. A 40 foot ladder is necessary to reach the roof from the ground and I’m not comfortable working so close to the edge of the roof. Time to hire a professional roofer, but none were available on short notice. What to do?
I got lucky and noticed a roofing crew working in the neighborhood. I asked the foreman if I he could install the new vent flashing. He said they were almost finished with the current job and could send someone over in 45 minutes. He asked if I had the new vent flashing, I said yes and showed him the Oatey No-Caulk flashing. He said he would install my flashing and add a rubber rain collar for extra protection for $50.
Two men from the roofing crew a short while later as promised. They setup a 16 foot ladder by the garage and bear crawled up the hip ridges with a big block of foam rubber (i.e. an old couch cushion) wearing regular tennis shoes with amazing agility! Compare this to my Poor’s Man’s roofing shoes in this article. In this photo the roofer is getting into position to start work.
Roofer Bear Crawling along the Roof Hip
Here the roofer has pried up the nails and is removing the old vent pipe flashing. The block of foam rubber grips the roof so he doesn’t slide off. The new flashing is tucked under the edge of shingle above him so it’s doesn’t slide away.
Removing the old Roof Vent Pipe Flashing
The new flashing is slide over the pipe, tucked under the shingles on the high side, and nailed to the roof.
BASF SONOLASTIC® NP 1 roof sealant is applied to the nail heads and bottom tabs of the roof shingles that were raised to install the flashing. This makes everything waterproof and ensures the shingles are glued to the next row so they won’t be lifted by the a strong wind.
Roof Sealant is Applied to the Nail Heads
Rain Collar – Fix a Leak in the Rain
Rain & Repair Pipe Collars are simply the rubber boot without the metal flashing. It acts like an umbrella to shed water over a cracked boot. A rain collar costs $5 to $10 and can be installed while it’s raining or wet for an emergency fix. No caulking, it stretches over the pipe for a water tight seal.
This is the new roof vent flashing with an added rain collar for extra protection.
New Plumbing Roof Vent Flashing with Rain Collar
Cracked Vent Boot – Post Mortem
The boot on the old Oatey all-plastic vent flashing was severely cracked/split in the places. This broke the watertight seal around the 2″ PVC vent pipe and allowed rain water to leak in and run down the vent pipe onto the drywall ceiling. This vent boot failed after about 10 years on the southern exposure of the roof.
Oatey - Cracked/Split Boot on Vent Pipe Flashing
A side view of the old vent flashing:
Oatey - Cracked Plumbing Vent Boot Flashing
I’ll have all my vent boots replaced with lead flashing when the roofing companies are less busy in a few months. Lead flashing lasts practically forever and almost never leaks because the rim of the lead flashing is folded into the top of the plastic vent pipe for a 100% seamless and waterproof installation. The rubber vent flashing costs $7 compared $30 for a lead flashing. The reliability of lead flashing is well worth it in my opinion.
Take care,
Bob Jackson
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Thank You for this information. I’m no roofing expert..well..I know a heck of a lot more now thanks to your pictures and links. The Rain Collars are great. It was impossible to purchase them locally in my City of Austin, Texas. Nobody stocks them! What A Quick Fix. Thank You Again. Johnny Goyen Austin, Texas
If a rain collar isn’t immediately available, you can always cut out the rubber boot from a standard flashing and slide it over the vent pipe to cover the cracks in the old boot.
Thanks,
Bob Jackson
My old boot looked like it was melted and separated from the plastic pipe just enough to leave a space for rain to enter. I was able to remove the rubber boot from a new aluminum flashing by pulling it out of the channel it’s tucked into. If you pull hard enough it will come out. I cleaned the deteriorated rubber from the old boot with a putty knife and sandpaper and siliconed the gap on the old boot for added protection. I applied a little dish detergent to the plastic pipe to make the rubber slide on easier and slid the new rubber boot on without the metal flashing creating a little “umbrella” directly over the existing boot. A quick fix that should last for as long as the new rubber boot lasts for less than $7.00.
Yes, that will work. You’ve made a field-expedient rain collar and avoids removal of the old boot flashing.
I just repaired 4 leaky roof vent pipes. I used the plastic oatly roof vents I got from home depot $7 per piece. There was nothing wrong with the existing flashing. I simply cut out enough of the new piece and slid down over the existing flashing. I used a little ‘Roof Jack’ petroleum based asphalt sealer on the top of the old one, so when I pressed the new piece that I made it would have something to adhere to. What I didn’t realize is the in small words on the new Oatly vent flashing, which is made of all plastic and softer rubber to seal around the pipe, are words that say ‘Petroleum Based Sealants should be avoided’ Do I have anything to worry about? Will this type of sealant cause any harm to the plastic/rubber?
I’ve seen roofers do exactly what you describe – it’s quick, inexpensive and avoids disturbing the shingles when a proper rain collar isn’t available or the weather is cold and the shingles may crack.
The petroleum-based sealant can attack the vent boot rubber. Check it in a week and again in a few months. I doubt it will crack immediately but will probably shorten the lifespan of the boot. Pick a warm day next Spring to replace the entire boot and add a rain collar.
Thanks Bob,
Certainly will do as you advise.
Your post is very useful. The roofer that I hired used DAP® ALEX PLUS® Acrylic Latex Caulk Plus Silicone to seal the nail and gap between new vent boot and the pipe since he had to tear off the inner ring to fit in the pipe. Is this type of sealant sufficient enough?
Roofing applications are not listed in the “Suggested Uses” section of the DAP® ALEX PLUS® Acrylic Latex Caulk Plus Silicone technical bulletin.
Whereas the SONOLASTIC® NP 1™ data sheet states under the “Where to Use” section (partial list follows):
* Roofing
* Wastewater treatment plants
* Dams
* Spillways and storm drains
* Wetwells and manholes
* Interior and exterior
* Above and below grade
* Immersed in water
* Clay & concrete roof tiles
A key product spec. in my opinion is the “Joint Movement Capability“:
* +/- 35% for the BASF NP1
* +/- 12% for the DAP ALEX PLUS
because roofs expand and contract a lot between the cold nights and roasting hot sunny days.
Given that the DAP ALEX PLUS product is not specifically rated for roofing applications and the wide variety of high performance roof-rated caulks available at roofing supply stores, I’d be disappointed with your roofer.
Thanks Bob! Do you have any suggestion? Should I have him come back to take out the DAP Sealant and reapply the Sonoplastic NP1 to the nail heads?
He did apply the TAM-PRO PREMIUM SBS (http://www.tamko.com/Cements-Coatings/TAM-PRO/ProfessionalMastics-Cements-SBSAdhesives/Q-20PremiumSBSFlashingCementTube) under the bottom tab of those shingles that were raised to install the flashing.
I did ask him to apply the TAM-PRO Premium SBS to the nail head as well but he said the DAP sealant is good enough.
I’d have the roofer come back out, scrape off the DAP ALEX PLUS and reseal the nail heads. A dab of the TAM-PRO PREMIUM SBS Q-20 asphalt flashing cement on the nail heads would’ve been OK, so I wonder why he used DAP instead?
The risk with the DAP caulk is it may peel or crack after a couple of seasons, but it’s not like it’s an emergency. It’s more about a doing a quality job and using materials that have comparable service lives. If rain water worked it’s way around the nail head, what’d you see is a water stained area under the roof deck from inside the attic, which could over time deteriorate as the glue in the OSB or plywood deck failed. If you had your roof reshingled down the road, the next roofer would say that section of roof deck needs to be replaced for an extra charge.
I couldn’t find the Sonalastic sealant at the local store. I might order it online but that will take time. Can I substitute it with DAP® 3.0™ Advanced Blacktop & Roof Sealant with Kwik Dry® Technology (http://www.dap.com/docs/tech/00010054001.pdf) being sold at Home Depot?
For the DAP sealant, that can be scraped off even after more than a week after it was applied since the roofer prob can’t make it back till the coming weekend?
The DAP 3.0 Roof Sealant will be fine for sealing the nail heads.
> For the DAP sealant, that can be scraped off even after more than a week after it was applied
> since the roofer prob can’t make it back till the coming weekend?
A property of silicone & latex caulks is they are easy to scrape or rub off even when cured. Scrape off what you can with a small putty knife, the rest will rub off with your thumb. You need a clean surface for the roof sealant to adhere directly to the flashing.
Finally got roofer back to redo the job. Beside having him sealing around the edges of the boot, I also have the roofer apply the Sonalastic sealant between the area where the plastic part of the boot made contact with the vent PVC pipe as extra precaution. Will that be a problem? Does the chemical in the sealant cause any damage to the PVC pipe? Thanks!
> I also have the roofer apply the Sonalastic sealant between the area where the plastic part
> of the boot made contact with the vent PVC pipe as extra precaution. Will that be a problem?
It wasn’t necessary to apply sealant there. The boot is designed to hug tightly around the vent pipe to make a watertight seal. The sealant won’t prevent the boot from cracking over time due to UV light damage from the sun. The rain collar is your best protection *in addition* to the boot. The rain collar “floats” freely as it’s only attached to the vent pipe, experiences no stress due to heat contraction/expansion of the roof and shields the vent boot from UV damage.
> Does the chemical in the sealant cause any damage to the PVC pipe?
The sealant won’t bother the PVC vent pipe. PVC is very resistant to most chemicals.