# Time to fix and re-engineer the stink pipe up on the roof before winter!



## Don2222 (Sep 10, 2012)

Hello

*Well I wonder if anyone else has a vent pipe coming out of the roof that is too short?*
*You may and not know it?*

From http://www.doityourself.com/forum/plumbing-piping/351561-vent-pipe-roof-whats-min-height.html#b
"According to my code book from IPC, unless some changes have been made, The lowest acceptable height of a stack in NH is 12". We have snow here so where you live may be different. And must be 2' above and 10' away from any opening window."
However I have also seen 6" as a min and recommended height of 18" ! ! !

Well I have the 12" height from the roof here in Salem NH done in 1962. I am sure that is not correct. There is alot of warm air from the shower and other fixtures in the full bath that comes out of the stack and condenses to melt the snow and cause re-freezing and such on the roof. I also believe that this has caused the rubber boot to become so brittle it broke and now there is a Huge space where water can get in! ! !

So we cut the old boot away and put a new boot and used a whole tube of black roof sealant! Using 3" PVC and a clamp, extended the pipe to 25 Inches! Above all codes and more important above all snow! I used some black grill paint to make the copper, PVC, stainless steel clamps and the aluminum boot base all the same color!

See pics click to enlarge!


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## heat seeker (Sep 10, 2012)

I  have a different situation - and this is my second house that does it. I have two soil pipes going up through the roof, since the baths are not above one another. When the wind is from a certain direction, and certain house windows are open, the wind blows in one pipe, carries the stink out the other pipe, and it follows the roofline and side of the house and comes in the windows - and it stinks!

My cure is to put aluminum foil over one pipe, with a few very small holes in it. That keeps the wind from blowing through the pipes, but doesn't interfere with the venting. 

It took me a while to figure out what was going on the first time. I looked everywhere for the source of the smell, then one day I figured it out. A quick trip up on the roof, and fresh air ruled once again.


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## Don2222 (Sep 11, 2012)

heat seeker said:


> I have a different situation - and this is my second house that does it. I have two soil pipes going up through the roof, since the baths are not above one another. When the wind is from a certain direction, and certain house windows are open, the wind blows in one pipe, carries the stink out the other pipe, and it follows the roofline and side of the house and comes in the windows - and it stinks!
> 
> My cure is to put aluminum foil over one pipe, with a few very small holes in it. That keeps the wind from blowing through the pipes, but doesn't interfere with the venting.
> 
> It took me a while to figure out what was going on the first time. I looked everywhere for the source of the smell, then one day I figured it out. A quick trip up on the roof, and fresh air ruled once again.


 
Good thinking! You could also put 2 90 Deg elbows on the top of the vent pipe so air can get in but no wind.


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## Highbeam (Sep 11, 2012)

The old boot was done wrong and needed to be replaced and properly roofed. The extension will work great.

The roofing job you did needs to be tore out and done properly. Use no cement and leave no nailheads exposed. You didn't even shingle over the flange. Sorry.


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## ironpony (Sep 11, 2012)

Highbeam said:


> The old boot was done wrong and needed to be replaced and properly roofed. The extension will work great.
> 
> The roofing job you did needs to be tore out and done properly. Use no cement and leave no nailheads exposed. You didn't even shingle over the flange. Sorry.


 
what he said^^^^^^^^^^^^^^^^^^^^ "A" for effort but you created another problem when solving the first one


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## PapaDave (Sep 11, 2012)

Should have at least put the top portion of the new boot under the shingles.
Highbeam and ironpony are correct.


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## Don2222 (Sep 11, 2012)

Hello

You cannot see from the pics but the top of the flange IS under the shingles. I agree this is temp. If I took the shingles up they would crack and need to be replaced. this is better than before for now!


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## RichVT (Sep 11, 2012)

Unfortunately that rattle can of grill paint that you used contains solvents that can cause the new rubber boot to fail prematurely.


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## Don2222 (Sep 11, 2012)

RichVT said:


> Unfortunately that rattle can of grill paint that you used contains solvents that can cause the new rubber boot to fail prematurely.


 
What paint would you use on the stainless steel clamp and aluminum and copper?


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## maple1 (Sep 11, 2012)

Don2222 said:


> Hello
> 
> You cannot see from the pics but the top of the flange IS under the shingles. I agree this is temp. If I took the shingles up they would crack and need to be replaced. this is better than before for now!


 
That must be a really deceiving picture. Actually, I think the flange should be under the shingles on the top and the sides? Sides maybe debatable. If it's only temporary you might be OK, but better check the goop on a regular basis - those flanges like to wrinkle and break seals.


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## Highbeam (Sep 11, 2012)

maple1 said:


> That must be a really deceiving picture. Actually, I think the flange should be under the shingles on the top and the sides? Sides maybe debatable. If it's only temporary you might be OK, but better check the goop on a regular basis - those flanges like to wrinkle and break seals.


 
Top and sides should be under the shingles with a healthy 3/4" gap between shingle cutout and the jack's cone to allow junk to flow around the cone. No nails exposed whether cemented or not, and no cement.

Even if the top of the flange is shoved slightly under that next three tab you will notice that there is a gap between two tabs on the flange so it will leak.

The shingles were not flexible at all? Even in this heat? Usually you see some curl when they get that bad. The proper thing then is to remove shingles as necessary to do the job.


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## RichVT (Sep 11, 2012)

Don2222 said:


> What paint would you use on the stainless steel clamp and aluminum and copper?


 
Latex is usually recommended but of course probably won't last as well as solvent based.

Usually just the white PVC pipe gets painted.


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## Don2222 (Sep 11, 2012)

Highbeam said:


> Even if the top of the flange is shoved slightly under that next three tab you will notice that there is a gap between two tabs on the flange so it will leak.


 
Yes, but if it leaks a bit the water will hit the old witches hat and still not go under the shingles just weep out the bottom of the new witches hat.
Correct?

Also the rubber part was not painted.


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## woodgeek (Sep 11, 2012)

Or you could just put a STUDOR valve in your attic...

http://www.ipscorp.com/plumbing/studor

I dislike all roof penetrations.


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## Don2222 (Sep 11, 2012)

woodgeek said:


> Or you could just put a STUDOR valve in your attic...
> 
> http://www.ipscorp.com/plumbing/studor
> 
> I dislike all roof penetrations.


 
Good idea!


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## Morgan (Sep 11, 2012)

You wouldn't get away with a STUDOR here in Canada for you main stack. All new constructions requires at least one 3" vent to to terminate to fresh air.  This 3" vent must be increased one size before it penetrates the roof.  So basically every house has at least one 4" penetration through the roof (to prevent frost closure) and then maintains a 3" minimum size right out to the septic or sewer. Air admittance valves are legal under the Canadian plumbing code, but my province for some reason overrides the NPC and makes them illegal to use, although they are used all the time here on non-permit jobs


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## Don2222 (Sep 11, 2012)

Morgan said:


> You wouldn't get away with a STUDOR here in Canada for you main stack. All new constructions requires at least one 3" vent to to terminate to fresh air. This 3" vent must be increased one size before it penetrates the roof. So basically every house has at least one 4" penetration through the roof (to prevent frost closure) and then maintains a 3" minimum size right out to the septic or sewer. Air admittance valves are legal under the Canadian plumbing code, but my province for some reason overrides the NPC and makes them illegal to use, although they are used all the time here on non-permit jobs


 
That is good to know.

I am in NH on the Border of MA, This is the code for Mass
Location: Massachusetts
MA Plumbing code says this:
_*10.16.6 *_
_*(f) Frost Closure. Where frost closure is likely to occur, each vent extension through a roof shall be at least three inches in diameter.*_

*Definition of Frost Closure*
Whenever a vent is extended through the roof the portion of that line above the roof will remain at approximately the same temperature as the outside air, which as you know, in mid winter in Massachusetts that can range from sub-freezing (32degF or less) to sub-zero temps.
When hot water is discharged into the drainage system it produces warm water vapor that rises up the vent lines. As that warm vapor comes in contact with the cold pipe it will instantly condensate on the inside of the pipe wall and freeze in place. Generally the amount of ice that will build up on the inside of the pipe wall will not exceed about 1" however if you have a 2" diameter vent and 1" of ice builds up on the walls it would result in closing the vent completely.
To compensate for frost closure the plumbing codes state that in regions subject to frost all vent opening passing through the roof must be increased to a minimum of 3" diameter at least one foot inside the attic space. (*Some local codes require 4"*).


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## woodgeek (Sep 11, 2012)

I think STUDOR allowance in the US varies...you would need to check with local code official.


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## Dune (Sep 11, 2012)

woodgeek said:


> I think STUDOR allowance in the US varies...you would need to check with local code official.


 
Yep, check with your local inspecter.


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## Don2222 (Mar 7, 2013)

Hello

Here is the results!

The extension really does prevent heat loss, melting and water damage and ice damming!


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## mepellet (Mar 8, 2013)

Now, what is causing the snow to melt on the roof in that area? Hmmmm.


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## Don2222 (Mar 9, 2013)

mepellet said:


> Now, what is causing the snow to melt on the roof in that area? Hmmmm.


 
Good question! That is right above the wall between the bathroom and living room close to the front entrance to the house? The strange part is that it is right above a vented soffit?


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