# Leaky vent stack, need advice on materials and install



## tinner666 (Mar 14, 2005)

Here's a link to a power vent install. It's the same as yours, only LOTS bigger. No need for cement anywhere. I just toe-nail the sides down so the shingles cover the nails.. One nail in each upper corner.
http://www.albertsroofing.com/Power%20Vent%20Installation.htm

Buy 2 of the ABS 3 in 1 collars, Tear for the 3" pipe, (it looks like ?). I cut the entire flange off the second one and just slide it down the pipe to cover the rubber boot on the first one. Should last 15-20 years that way.


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## Windows on Wash (Aug 30, 2011)

Interesting vent flashing approach.


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## tinner666 (Mar 14, 2005)

Windows on Wash said:


> Interesting vent flashing approach.


 You think? It's a simple fix when the call comes in and that's what went south in the 8th year. Doing it on install makes it last longer.
Here's one I did when the owner didn't want copper or lead.
By comparison, here's a no-caulk collar still going strong on a 1951 house. I took the pic in Dec.


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## tinner666 (Mar 14, 2005)

I need to take pix of the stack of aluminum ones in the shop that have the ruber ring. When they go south in the 8th. year, the water pours into the house. The rubber is at roof level, not on top of the dome.


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## nowwhatnapster (Oct 26, 2008)

I picked up flashing similar to the photo below from HD yesterday. This is actually a photo of the other vent pipe on my house. Looks to be in ok shape except those nails at the bottom of the flashing bother me. They shouldn't be there/should be covered in cement? 

Hopefully I'll get to install this weekend.


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## Windows on Wash (Aug 30, 2011)

You can purchase replacement boots at HD or Lowes.

That boot looks okay and appears to be installed pretty well. Might be a good time to swap them both out and yes, a dab of sealant on the exposed nails is a good idea.


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## mae-ling (Dec 9, 2011)

Seal with roofing cement/tar between back of shingles and top of flashing where it goes under the shingles or over the shingles.
Assuming thisa is not a not tar type flashing


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## tinner666 (Mar 14, 2005)

Yours looks OK so far, but the corners should never have been nailed. When I used to use those, I'd flex the flange so corners ctayed tight and the toenail the flange so the nails were under the shingles.

That's the type I quit using. When that rubber fails, it fails right in that crease and water will pour into the house. The ABS ones will split too, but won't leak as bad. Doubling extends their life. Or just wait 10 years, buy a new one, cut the flange off and slide it over the existing to reseal it.


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## vandel777 (Jul 27, 2012)

i would suggest going with a hard plastic pipe flange, here is link that shows you the process of the in-stallion (http://www.hammerzone.com/archives/roof/maintenance/reshingle/install_1/vent_flashing.htm). it didnt quite mention where which course of shingle is the right one to go under the flange before nailing it to the roof deck. the way i judge mine is when i get up to the pipe i will want the top of the shingle to be atleast 1/4 to half way up pipe (note: not every pipe flange you go to shingle will have the exact placement, therefore shingling up to them leaves you with a different distance from the top of your shingle to the pipe, it could be little bit below the pipe or above so if your below the pipe chances are you should throw another course of shingles on before you nail the pipe flange to the roof deck.
along most of these style pipe flanges will a risen piece of plastic for the water to follow down, so when your going to nail your flange make sure you keep your nails on the outside of this water guider.

let me know if my info helped any


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## nowwhatnapster (Oct 26, 2008)

Thanks for the info about the full plastic flanges. I went with the cheap aluminum/rubber flange by oatey. The roof only has about 5 to 10 years on it, so I will replace these with something better when the time comes.








Starting to get into the finer details of this task and I have a few more questions.

I picked up some Karnak #19 Flashing Roof Cement. I am not entirely sure if this is the right product for the job. Can anyone confirm?









I was trying to find hot-dipped galvanized roofing nails at my local HD but wasn't having any luck. All I could find was electroplated. Am I looking for the wrong kind of nail? Is there a better kind of nail I should be looking for?

Also, what length of nail should I be looking for? I know its supposed to penetrate 3/4" into the deck, but I'm not sure how to measure so I get the right length. I beleive there is only 1 layer of shingle, felt, and clapboard decking.


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## joecaption (Nov 30, 2011)

SIlicone or that caulking will work, just needs a small dab.
1-1/4 nails, if there installed under the shingles elecro plated will work.


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## nowwhatnapster (Oct 26, 2008)

Would aluminum nails be superior to the galvanized variety for this application?

My googling confirms your recommendation of 1-1/4" for a single layer of shingle. Thanks.


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## Michael Thomas (Jan 27, 2008)

Even year I inspect _dozens_ of rubber-gasket type vent stack flashings which have failed. 










IMO, the "old school" solution of a lead flashing bent inwards over the top of the stack is FAR superior.










I have seen literally thousands of these - without finding _one_ which has failed except as a result of mechanical damage.


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## nowwhatnapster (Oct 26, 2008)

Well the job is done. I did not execute as well as I could have. I think I made some mistakes, but I don't think it will leak unless we have a major storm that blows rain up and under the exposed flashing.

Here are some pictures. I'll let you draw your own conclusions:
#1 - Removing the shingles & makeshift flashing









#2 Same as #1 just further along.









#3 Cut a replacement shingle because the old one was hacked to fit and in two pieces. Also note the first nail I drove on the far right of that shingle I put in the strip by accident. I covered it with roofing cement.









#4 Flashing in place with roofing cement applied to top. I did not apply any cement on the underside, I was thinking this was a mistake, but at the time I was unsure and decided omitting it would not be a huge error. Feel free to correct me here. Also note that I only nailed the top 2 corners of the flashing. In hindsight I should have put 1 nail in the middle of the top edge and probably 2 midway down the flashing on the edge. Again, I was unsure and felt omitting would not be a huge error.









#5 another shot of the 2 nails at the top. Again I feel I should have put 1 in the middle. I used hot galvanized nails 1-1/2". Tad longer than needed, but they were readily available.









#6 Final product. I re-used some of the shingles that I felt were in good condition so my repair would not stand out so much. Perhaps I can spray paint the black shingles so they blend better. The black splotch on the red shingle is from the old "flashing" it peeled off easily and was not terribly tacky nor missing particulates so I decided to reuse it.









I will definitely do a better job next time around. A little more research and time to execute would have made today's job better I feel. The only major thing I am concerned is that I did not nail the flashing farther down. The more I think of it the more I feel a gust of wind might lift it out of position. Thoughts?


@Michael Thomas, the lead flashing that goes all the way up and into the pipe does seem the superior method of flashing. I saw a copper variation of this online which I would prefer over the lead which would eventually leach into the run off.


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## stuart45 (Jun 20, 2009)

[]


Michael Thomas said:


> Even year I inspect _dozens_ of rubber-gasket type vent stack flashings which have failed.
> 
> 
> 
> ...


Got to agree 100% with Michael Thomas here. 
I used a lead slate where the oil boiler flue comes through the roof of an extension I'm building at home. The only difference is that the flue goes well above the ridge, so a cap and sealant are used instead of it going up to the top. Lead slates and flashings can last well over 100 years. 
It's best to put some patination oil over them when installed to prevent the white staining on the roof though.


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## tinner666 (Mar 14, 2005)

I thought I mentioned it before. Maybe not. 
Under the shingles on the sides, I toenail the flange, just snug to prevent uplift. I've ever caulked the top of bottom of the flange, though if I was going to do so, I've put the caulk at the very outer edge ONLY, after toenailing.

The lead or copper collars are superior. As Michael showed in his pic, the plastic bottom ones only split on the top, so the only repair truly necessary is to cover the top with another one, with the flange removed. Doing it at the beginning should give 20 years, instead of 6,8, or maybe even 10 years between leaks. 
You can't do that with the metal/rubber ones. Notice the brand name.


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## rtoni (Jul 18, 2007)

tinner666 said:


> Here's a link to a power vent install. It's the same as yours, only LOTS bigger. No need for cement anywhere. I just toe-nail the sides down so the shingles cover the nails.. One nail in each upper corner.
> http://www.albertsroofing.com/Power%20Vent%20Installation.htm


hey tinner - i read the article at that link and that might explain why I'm seeing a problem on my wood stove flashing. My apologies for jumping on this thread, but this is maybe an "a-ha" moment for me.

I have a wood stove flashing assembly for the insulated stainless steel chimney (flashing is all one piece, galvanized). The installer apparently did NOT follow the 50% rule of thumb for running shingle under the flashing. They did what the link suggests that "a lot of roofers do" - they hid most of the flashing. It's a nice looking job, but I just noticed a slight leak after a windy downpour this past weekend - right under this area (a couple drips on the corner of my woodstove). I went up on the roof and it seems to me that the water running down the flashing probably got pushed sideways by the wind and got under the edge of the shingle and beyond. 

This is a relatively new roof on an addition, but no warranty left. I really hate to have to tear out this flashing and re-install. All the materials seem to be in great shape, but I'm thinking the problem is the way it was installed - it should have been done as in the link you posted. Can I seal under the edges of the shingles, on top of the flashing (down the sides) to address this issue? I'm ok with a temp fix as the older part of my roof will probably need a replacement in 1 or 2 years and I can get the roofer to take care of this at that time with a more permanent fix. 

Thanks for the help......


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## tinner666 (Mar 14, 2005)

Instead of caulking anything, other than nail holes, cut those shingles off the bottom of the flange and open it up for water flow. Then look under the side shingles and if you see any squared off tops, taper them back. Caulk any holes in the bottom of the collar. That would give a better job.


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## Pittsville (Jan 8, 2011)

Haven't seen this mentioned yet. Another possible solution...

http://www.permabootstore.com/


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## rtoni (Jul 18, 2007)

tinner666 said:


> Instead of caulking anything, other than nail holes, cut those shingles off the bottom of the flange and open it up for water flow. Then look under the side shingles and if you see any squared off tops, taper them back. Caulk any holes in the bottom of the collar. That would give a better job.


thanks very much for the reply. I hope I didn't confuse things with my post when I said they "hid" the flashing - I don't have a pic from my roof so I stole a snip from your link, as this is pretty much exactly how my flashing was installed too (the flashing is exposed at the bottom but the shingles overlap the sides of the flange all the way to the bottom, except for the last inch or so). 

I put red outlines around the shingles that I think water got pushed under but to be honest could have also been higher up on the side. So should I cut the last (bottom) overlapping shingles off over the flange (water can run off without getting under this shingle?), and also taper any square tops --- or should I just taper any square tops? Sorry if I'm being really thick here, just want to make sure I didn't get good advice based on a bad description on my part earlier. 

thanks again...


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## tinner666 (Mar 14, 2005)

Just cut the square tops off. They catch lots of water and send it under the roof.


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## rtoni (Jul 18, 2007)

I will try that - thank you very much for your help....


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