Replace roof vent pipe on top of shingles over ice shield

I need to replace the vent pipe boot flashing/flange.
I have 3 rolls of BIRD ice shield, up to 9 feet from roof edge.
I worry that I might tear the ice shield when I take off the shingles surrounding the vent pipe. I also worry that the old nail holes may leak, since the ice shield no longer seal around the ripped off nails.

should I cut a piece of new ice shield, and lay it on top of the existing ice shield (possibly damaged slightly). Can I use the ice shield from Grace (I used BIRD on my roof).

Also the new ice shield patch cannot be tugged in under the next roll of ice shield further up the roof. Is that OK.

This is my first time posting a question on Thank you for any help on such an elementary question.

Why is there 9’ worth of ice shield on your roof? Is it a low pitch or something? Yeah you can just cut a small piece and go over the existing to cover nail holes. Yeah you won’t be able to lap it under the existing at the top but your only real other option is to tear off all the shingles till you are past the ice shield which would be way overkill. No need to make a simple job way harder than it needs to be :wink:

p.s. don’t get fooled into the “ice shield is the only reason roofs aren’t leaking at eves, rakes, flashings, penetrations, and everywhere else you could possibly use it” b.s. lol.

Thank you for responding to my questions in just 4 hours.

After the record breaking snow fall of 2014/2015 winter in Boston, with a record breaking 113.3 inches, 2 of my local roofers suggest 100% coverage with ice shield, even though my house has a 6/12 pitch. Is that a bad idea ? I was told by another roofer, that 9 feet already covered half of my roof, that I should let the house breathe. So who should I believe.

My house is an Acorn deck house, with cathedral ceiling, and no attic.

In 1995 I re-roofed my house, after a severe winter of 1994/1995 with 150% of normal snow fall… Lots of folks had to de-ice their roof. I called BIRD (now Certain Teed), which is local to me in MA, they recommended 9 feet of ice shield.

I like the idea of 100% ice shield coverage, should I do it ? My roof is now some 20 years old, and could be ready for re-do.

Covering the entire roof deck with ice & water shield is usually a complete waste and is not usually recommended by experienced roofers.

Some of our newer roofers seem think that ice & water shield has magical properties, it does not .

Yeah I am 100% against covering an entire roof with ice shield. All you will have is a bigger expense right away and an even bigger one next time your house needs a new roof (it will make tearing off the shingles much harder as shingles stick to it). I find its usually just salesmen who recommend doing so as they like to rely of flavor of the week type gimmicks to get homeowners attention.

When I was less experienced I bought into the hype myself and it bit me in the ass. I roofed a 2/12 section with shingles (not recommended) and thought if I put ice shield under it “how can it possibly leak?” Well guess what, it did, bad, multiple places, nearly every time it rained. Went back tried to stop in mulitiple times, nothing worked except replacing with a system designed for that pitch. I realize your situation is different but I’m just telling you that I know first hand ice shield is not guaranteed to keep water out of your house if it gets under the shingles.

From the sounds of it your 20 yr old roof did the job just fine so no need to reinvent the wheel.

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Yes, you can put a patch piece of I+W on top of the existing.

Thank you for taking the time to answer my questions. . Never before did I have access to such direct professional help. I can now be much more grounded in my undertaking.

I do have some further questions. I can buy a roll of GAF I&W shield for $68, or one made by GRACE for more than 2 times as much. I only need enough to patch around 4 vent pipes. Is the GAF product good enough ? Can I buy some remnant pieces somewhere for less ?

You have convinced me not over do I&W. But here is my concern. This winter, MA has more than 100 inches of snow fall in six weeks in FEB/MAR. At one point, my roof has more than 2 feet of snow accumulation. It seems that direct sunlight (12pm to 3pm) can be enough to turn them info slush, then re-freeze to create ice dam, higher up on the roof beyond the reach of my I&W shield, especially next to the skylights.

I don’t like to use chloride which causes metal to rust. If I do not use I&W, then what could be my backup solution. My deck house is too high for me to reach with a roof rake.

Get some neoprene caulk and caulk over the old nail holes, you can put a nail in the hole first if you wish.
Then do the repair, don’t buy a whole roll just to use 2 sq/ft.

Then forget about it, it will be fine.

Yeah just do the repair like axiom said. No need to waste money on a whole roll for 4’ worth of I+w.

Did you ever have any issues with ice dams in the past? Did you have to do anything to scrape snow and ice off in the past or melt the ice with salt? If the answer is no than I don’t understand why you would be worried about it now. To be honest sometimes its easier to just give the homeowner what they want rather than try to argue them out of it. While its not something that I would ever do on my own house but if it will make you that much more confident in your roof just use I+w over your whole roof deck. If the rest of your roof is ventilated properly your roof will still “breath” just fine.

My acorn deck house has cathedral ceiling and no attic. The tall ceiling extends out to form a 2.5 feet overhang.
That means “whole-roof I+W shield” would leave no room for breathing. So your suggestion of not over doing it makes sense to me.

With this year’s record breaking <113 inches of snow fall> in just 6 weeks., every other homes have more serious roof leakage, and many (more than half) among them hire professional help to de-ice the roof (by steaming), at a cost of up to $1100 per service call.

I know (from photos taken on my roof by my handyman) that I have ice dams forming around my skylight windows, half of its (skylight window) length is above my 9 feet I&W shield. Despite of their presence, there is no leakage track mark starting from these skylight windows. But I reason that these higher-up ice dams should cause water built-up behind them, should have caused water to seep through the shingles above the 9 feet length of I&W shield.

I do have roof leakage for 3 weeks, at the rate of some 2 buckets a day, from multiple spots, all about 13 inches from the inside wall facing outside. I reason that this can only come from the one vent pipe about 2 feet from the roof edge, but not from the skylight windows.

Since I now believe that ice dams can form anywhere, just by a few hours of direct radiant heat from the sun, and a cold night (below zero degree Fahrenheit), I am now paranoid about roof leakage in upcoming winters.

If my reasoning is correct, then it would not be enough for just good attic ventilation. (Now of course I don’t have an attic area anywhere in my house.)

I had hope that I&W shield would be a good backup solution. The roof is too high for me to use a roof rake. And I cannot afford to spend some $600 for de-icing, 2 times (like this winter) in the winter.

Getting back to my question on overlaying new I&Wshield patch above existing one under the vent pipe.

What if the existing layer got scratched or torn (not just holes from old nails), as I peel off the old shingles to replace pipe flashing ?

If all this is remotely true you need a real roofer out there to ascertain wtf is going on and the best way to fix it.

A bunch of skylights in an unventilated vaulted ceiling, this needs special attention, probably a cold roof.
I’d guess it’s steep also.

There is a decent possibility that stuff is just done wrong and your roof is leaking because of it.

Ice & water shield isn’t magic, cheap nails rust out and leaks through the hole, some Ice & water shield(s) just plain don’t work at all.
Shingles & flashings keep water out, ice & water shield is secondary.

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Perhaps shingles are not the roof you want period. If someone told me they want a roof than is “ice dam proof” on their 6/12 roof I would recommend double lock standing seam. However you will not be excited about the $ that it would cost in comparison to shingles. Also, might as well put ice and water shield under the metal too, and don’t forget to put butyl tape in between the ribs. You need all the “extra protection” you can get.

And back to the original question, just buy a whole roll for your pipe flashing repair even though you will only use like 3% of the roll. I recommend the most expensive type you can find.

Sorry if I am coming off as a jerk but honestly it sounds to me like you just have a 20 yr old shot leaking roof and rather than just accepting it you want to blame ice dams/lack of ice shield/bad design/extra severe winter/negative karma/ect. What you really need is for someone to look at your roof (not just read your comments online) in person and come up with a proper ventilation system for your unique house then install a new roof.

In my opinion ice and water shield is and has always been a band aid for problems, not a solution. Even if it fixes them, it isn’t gonna for long.

I am excited to read your answers. They all sound right to me.
I feel impelled to write a summary of my take from your advice, in a few days.

I have a technical background, but am otherwise roof naïve.
One thing I am pondering. Why would a layman like myself, able to gain access to experienced tradesmen like yourself, and to get my answers so quickly. I assume that the community has a lot of worthy questions to post every day.

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I have confirmed that 2015 is the worst winter in Boston in 120 years.
The snow fall in 6 weeks in JAN/FEB amounted to 119.2 inches.
My neighbors & my church acquaintances have spent some $800 to $1500 to remove rooftop snow/ice in one to two steam removal visits. This seems to account for every other folks I know.

My handyman has gone up to my roof and took pictures showing plenty of ice formation…
I did not rake my roof because it is 2-3 stories up. My house is an acorn deck house. This house design (with cathedral ceiling & no attic) has existed for over 25 years. Deck houses are built by deck-house certified builders, so I trust that the basic roof design is sound. I did not have a roof leak for most of 20 years, although last winter my vent pipe flashings are faulty.

Does this means that I have to make my roof ice-dam proof by going to metal roofing for sure ?
I reason that ice formation can retain water puddle that is wider than the width of a shingle, and this can occur at any height, (say around the skylights) and not just at roof edge. Hence water can & will backup under the shingle between the courses, and finds a way to enter the house.

Metal roofing is not yet prevalent In Massachusetts. Only one of my neighbors installed one recently, after the winter.
But if I need to re-roof, then I should commit to a metal roof ?