# Leaking FLUE Pipe



## almazon (Feb 19, 2012)

Heya guys,

Its all started couple weeks ago when my wife brought my attention to a dark spot on the ceiling in one of the rooms' closets on the 3rd (top) floor.
I removed the sheetrock and found out an obvious sign of the leak:









I also poked the plywood with the long screwdriver and it was all soft. It needs to be replaced. Btw roof is 27 years old.

Then when it was raining I saw some drips from the opening. So its either bad Flashing or Storm Collar. Or both.









I understand that this is 6" Double Walled Pipe coming from the Furnace on 2nd floor via 3rd floor to the Roof:










I am planning to repair the leak in the next couple of days.
What I am going to do is:

- remove old shingles and underlayment
- cut off bad plywood
- add 2x4 to the side of Rafters
- screw in Plywood Patch
- apply New Underlayment
- install New Pipe, Flashing, Storm Collar and Cap
- finish with shingles

But I have a few questions...

1. Does this pipe necessary to be Double Walled ABOVE the roof?
2. Will this Cap (Type B) do the work OR do I need to install something more solid?









3. Is installation of the Storm Collar necessary?

I have trouble finding 6" Flashing for this job frm my local Home Depot or Lowes. I am planning to look for it in General Plumbing Supply store. If not then online.

4. Does it need to be a special kind of Flashing OR something like this (comes with Storm Collar) will do the job?









Also, I understand I will have to use Underlayment like Ice and Water Shield, but buying a whole $100 roll for 3' by 3' job is kinda breaking me.

5. Is there any Peel and Stick substitute you would recommend?

Thank you in advance,
almazon


----------



## hkstroud (Mar 17, 2011)

Why would you want to change the flue piping above the roof.

Leak is not coming from flue, it is coming from improper installation of flashing.
Flashing should be installed under the shingles above the flue and on top of the shingles beside and below it.

Your flashing is installed below the shingles on the down side of the flue. It should be installed above the shingles so that it sheds water just like a shingle.

You can see that the damage to the roof sheathing is on the down side of the flue pipe.

You should check other pipes coming through your roof for same error. This was probably done some time in the past when a roof was reshingled. If it was done this way here it was probably done the same way at other places.

Shop heating supply for flashing and storm collars.

A couple videos on installing flue flashing.


----------



## almazon (Feb 19, 2012)

hkstroud said:


> Why would you want to change the flue piping above the roof.
> 
> Leak is not coming from flue, it is coming from improper installation of flashing.
> Flashing should be installed under the shingles above the flue and on top of the shingles beside and below it.
> ...


Thanks, Harold!
And thanks for the videos!

I am totally, 100% agree with what you said. But that Flashing's top is under shingles while bottom is over them. Its just they covered the bottom in cement and it looks like shingles.

I went with new Chimney Pipe, Cap, Storm Collar and of course Flashing. Just out of esthetical reasons. It was all original and ugly. 

The only thing is that I have a problem with connecting new pipe to old elbow.

1. Can I cut new pipe's outer wall a little bit (at the end) to make it fit better? I am gonna use screws to secure them later...

2. Also, are you guys using OSB or plywood?

I've read that builders prefer OSB over plywood nowadays. I used 7/16 OSB and it does not feel any stronger than existing plywood.

Thanks again,
almazon


----------



## hkstroud (Mar 17, 2011)

People like OSB only because its cheaper than plywood.

You will probably have to take that elbow out, put in on the pipe and then shove the pipe up through the flashing from the inside. Then reconnect the elbow back to the lower pipe.

Either that or have some one manipulate the elbow as you put the pipe in from the roof.


----------



## almazon (Feb 19, 2012)

hkstroud said:


> People like OSB only because its cheaper than plywood.
> 
> You will probably have to take that elbow out, put in on the pipe and then shove the pipe up through the flashing from the inside. Then reconnect the elbow back to the lower pipe.
> 
> Either that or have some one manipulate the elbow as you put the pipe in from the roof.


Thanks, Harold!

So plywood is better? Well, at least it feels stronger. I feel more confident with it...

Thanks again,
almazon


----------



## almazon (Feb 19, 2012)

Heya guys!
Here's an update...

Last Saturday morning before going to work I finally finished this job.

I could be wrong, but it looked like the roof was Original and 27 Years Old.
As I suspected, there was a lot of rot. Old Felt was very brittle and easily to brake: 


















I cut off the 43"x32" openning. First I was going to use OSB...









...but then later switched to more-money Plywood:









I screwed it down with 2 1/4 inch exterior screws and covered the patch with 2 pieces (6' and 5' wide) of new Felt, carefully tucking it under old one.

I also went with new DuraVent 6" Elbow, 6"x12" Adjustable Pipe because I have trouble to fit new DuraVent 6"x36" Chimney Pipe into old elbow:









After new Flashing and Chimney Pipe were installed I sealed in between with Red silicone:









Then after Storm Collar I sealed it again:









...and, finally, Voila!









This morning it was raining. So far no leaks.
Waiting for big one to really test it out...

Thanks again guys for all of your help,
almazon


----------



## ZTMAN (Feb 19, 2015)

Nice Job
:thumbup::thumbup:


----------



## carpdad (Oct 11, 2010)

Maybe bad news. You're in NY. You may get fairly bad case of ice dam there, esp as the two roofs valley there.


----------



## almazon (Feb 19, 2012)

carpdad said:


> Maybe bad news. You're in NY. You may get fairly bad case of ice dam there, esp as the two roofs valley there.


Yes. You are absolutely right. As I am at the end unit townhouse, there is one neighbor's roof 1.5' below me and another 1.5' above.


----------



## almazon (Feb 19, 2012)

Guys,

Today it was (and still) raining all day. There is no wet marks anywhere on plywood.
BUT by the end of the day I found there is a dripping from INSIDE of the Chimney Pipe.

What does it mean?
Wind is blowing rain into under the Cap?

Thank you in advance,
almazon


----------



## almazon (Feb 19, 2012)

Or maybe I should get another cap?


----------



## Windows on Wash (Aug 30, 2011)

Sideways rain will allow water to enter the cap. Look at a another design perhaps.


----------



## craig11152 (Jun 20, 2015)

Maybe not a big deal but it looks like you put the plywood in the wrong way. It should run with the outer grain perpendicular to the rafters or trusses.


----------



## CodeMatters (Aug 16, 2017)

Nice looking job. :thumbsup:

Have to wonder if the the original problem was a result of the tar (or 
whatever it was) over top of the lower edge of the collar. As it 
deteriorated over time it may have left a pocket. 
Better to leave it a clean overlap as you have done. :thumbsup:


----------



## a912 (Oct 25, 2017)

almazon said:


> Thanks, Harold!
> 
> So plywood is better? Well, at least it feels stronger. I feel more confident with it...
> 
> ...


OSB is cheaper and stronger when installed properly


----------



## Windows on Wash (Aug 30, 2011)

Stronger is a pretty broad based term.


----------



## almazon (Feb 19, 2012)

craig11152 said:


> Maybe not a big deal but it looks like you put the plywood in the wrong way. It should run with the outer grain perpendicular to the rafters or trusses.


Yeah craig11152,

I gotta admit I missed that one. I will pay attention next time. I hope its not THAT big of the problem. Thanks for noticing!

Anyway, guys...

I replaced this DuraVent cap (that I really liked the way it looked):


















with this adjustable by GAF from my local Home Depot:









However, today it was raining and dripping again from UNDER the pipe that goes outside:









It looks like leak comes from the Cap, pipe's seam or where Cap sits on pipe.
Anyway, is this normal?

Thank you in advance,
almazon


----------



## Windows on Wash (Aug 30, 2011)

They are usually pretty tight. What you might be seeing, especially in the cooler months, is some condensation inside the piping when the combustion equipment first fires up.


----------



## almazon (Feb 19, 2012)

Windows on Wash said:


> They are usually pretty tight. What you might be seeing, especially in the cooler months, is some condensation inside the piping when the combustion equipment first fires up.


Thanks man for your input, but I don't think that's the case. I leaks (or rather drips hard) ONLY when it rains.


----------



## Windows on Wash (Aug 30, 2011)

As I said, the are usually pretty tight. 

Pull the cap then and seal the top of the seam where they connect. 

Then put painters tape on either side of the seam so that you don't goop sealant all over the place and caulk the seam. Take your finger and really tool the sealant into the seam and pull the tape for a nice clean line.


----------

