Offsetting 1.5" galvanized on a 22.5 degree angle? How? Possible?

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To make room for a solar panel layout,
I'd like to extend the following plumbing penetration to a spot higher on the roof. At this time I have access from above to the pipe embedded in the wall, and access to the roof below the 6" dimensional rafters.

The roof pitch is 6:12, which means 22.5 degrees. What's the best way to get this done, that leaves the line workable with a plumbing snake from above, if needed?

This must be maintenance free at the top plate junction, as that will be inaccessible after roofing. The existing galvanized waste vent is in good condition, though from the 1920's.

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Tuttles Revenge

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The way to do this is with 2 swing joints. Two 90° bends will allow you to attain any offset angle. Cut your vent in the wall, band on a 90 that turns to horizontal above the wall, then another that runs up at the angle you need in the ceiling.. Same as you penetrate the roof.
 

Sylvan

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You have a few choice for offsetting this line a 1/32 bend = 11.25 deg or 1/16 bend = 22.50 deg = or a 1/8 bend = 45 deg a 1/6th bend = 60 deg


You can get cast Iron no hub fitting and no hub couplings then you have choices

Having 2- 90 deg fitting s make it difficult to snake in case you need to

Also in certain circumstances I use galvanized drainage fittings with shoulder nipples if I do not have a lot of space

You can also buy a short sweep or 1/4 bend and wear goggles and use a grinder to make your own angles as required
 
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Thanks for the input so far!

The two 90's idea does not seem like it would pass a plumbing snake very well.

How about if I used one 45, plus then got someone to bend a section of 1.5" galvanized pipe to make up the remaining 22.5 degrees? So 45+22.5=67.5 degrees. Does the plumbing code allow me to bend a waste stack pipe????

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I not a plumber. I don't myself have a rig for bending pipe so stiff, nor do I have a thread cutter. But I have a local tool library, and can get something (or buy it, and donate it to the tool library).
 

Reach4

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How about if I used one 45
I looked at the math earlier today, and it looked like you would want a 63.43, if I did that right. A 45 and a 22.5 could give as much as 67.5 so a 45 and 22.5 would be enough to give the exact angle desired. (revised a few times)

I suspect gluing that up and getting it right the first time would be fairly hard.

For the galvanized to pvc, you would use a shielded coupler. Maybe have a street fitting grabbed by the coupling on one side, and the galvanized on the other.
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Let's see, I might have the angles a bit wrong.

6:12 pitch is 6 inches rise per 12 inches of run, or 26.57 degrees.
The pipe comes up vertically, so we're interested in 90 - 26.57 = 63.43 degrees.


The roof is a 50 year+ metal roof, and the junction will be inaccessible. It has to be very long lasting,
like the original 90 year old pipe it will attach to.

Is it practical to use a 45 degree elbow, plus then get someone mandrel bend the remaining 18.43 degrees into each end of a the diagonal pipe?
 

Kreemoweet

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TheOverThinker said:
... suggests bending pipe ...

Drainage pipe is NEVER bent, be it metal or plastic. Just how far does your diagonal section of pipe
have to travel? The pipe does not have to be perfectly parallel with the roof framing. If you cut your vent,
attach a rubber coupling and then a 45 plus 22.5 bend, and continue up with a length of pipe, the pipe will
grow nearer to the bottom edge of the rafters about 3/4" for every 1 ft of horizontal travel. Using a 60 will
make the pipe approach the top edge at a somewhat higher rate. These drop/rise rates
may be sufficient to keep the pipe in the framing cavity until the place you need to turn vertical. Then you
would just use the same bend(s) to reverse what you did at the bottom.
 
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The diagonal section is about 15 feet, avoiding the solar array.

There is a top of roof jack for running drain waste pipe under solar panels, but it's way better in this case to run under the roof.

Does plumbing code prohibit bending drainage pipe? Would I be allowed to use a 15 foot section of plastic pipe and take advantage of its natural flexing ability?
---------------------------------------
If I do use plastic, how is plastic pipe protected from the sun in roof vent applications, to prevent it getting brittle
over the decades?
 

Reach4

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I suggest you buy a street 22.5 and a 45 and some pipe to play with. The pipe would be to extend things to make measuring the angle easier. I think you will be able to figure out how to make the angle you need. The 3d math is beyond me, but I think a little manipulation and measurement will make you a believer.

I would not recommend a 45 elbow plus some Spaflex (or other PVC Schedule 40 White Ultra Flexible Pipe) to you, but I might be tempted do it myself, using pvc primer and glue to join to PVC fittings, if nobody was looking and I thought the 45 and 22.5 was beyond me. I am not a plumber.

The PVC or ABS 45 and 22.5 would make everybody who likes plastic pipe for vents happy.
 
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I did find a 22.5 in cast iron, which potentially could be coupled with jacketed rubber no-hubs.
It's just messy, and as I mentioned before if anything goes wrong, it can't be fixed without tearing the roof off again.

I don't actually like plastic pipes for vents... not for a 100 year "buy it forever" roof.

charlotte-pipe-cast-iron-fittings-162-64_1000.jpg
 
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wwhitney

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If you're saying that a tear-off would be required to access the connection, it sounds like the attic is inaccessible. In which case why do you have to follow the roof rafters? Just do a 67.5 degree bend, go as far as you need, and do another 67.5 degree bend.

If you do want to follow the roof rafters at 6/12 pitch, then if my math is correct, you can do it with a 45 degree bend and a 22.5 degree bend as follows:

Starting from plumb, have the 45 followed by the 22.5 all pointing towards the ridge, so you have a 67.5 degree net bend.
Rotate the 22.5 bend 40.4 degrees.
Rotate the 45 bend 16.1 degrees so that you are pointing at the ridge again.
This should get you to a 6/12 slope, i.e. a 63.4 degree bend, with a slight offset.

If you don't like plastic, your options are copper, cast iron, or galvanized, the bends should be available in any of those. Connecting to the existing galvanized is best done by cutting through it and using a shielded rubber transition coupling, unless you are lucky and have a coupling right there you can unthread.

Cheers, Wayne
 

Sylvan

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If you want to bend 11/2 galvanized pipe it can be done by contacting an electrician as some have large hydraulic benders or a pipe fabricating shop

When I worked on high pressure steam systems we had the bends prefabricated less change of failures and saves a lot of man hours from welding or threading. Less joints less chance of a leak

Check with local code officials

http://www.wermac.org/fittings/hot_induction_bends.html

I am glad you agree with me about trying to snake a line with 2 - 90 deg fittings

Also I do not use plastic except for chemical lines such as Chlorine
 
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If you're saying that a tear-off would be required to access the connection, it sounds like the attic is inaccessible. In which case why do you have to follow the roof rafters? Just do a 67.5 degree bend, go as far as you need, and do another 67.5 degree bend.

The attic ceiling space ranges from 6' at the center to 6" at the edges. Access to the top of the pipe is at the 6" part: functionally inaccessible.
The first 67.5 bend would result in the pipe hitting the roof decking.
 

wwhitney

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The first 67.5 bend would result in the pipe hitting the roof decking.
No, it would get you to a 5/12 pitch (actually 4.97/12), so you wouldn't be hitting the roof deck. You'd be dropping 1" / 12" relative to the roof deck. So depending on how far you have to go, and how high you put the 67.5 bend within the rafter bay, and your rafter size, you might still stay within the rafter bay.

Anyway, I think this thread has covered all your options, so you can pick the one you like best based on your personal criteria.

Cheers, Wayne
 
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OP here:
My jurisdiction does not recognize Air Admittance Valves (AAV's), and won't recognize them.
And this is an inappropriate place for one for two reasons: it can't be serviced because of the poor clearance, and
because of the heat of being right below a roof deck. When the rubber on the AAV eventually wears out and gets brittle,
there would be no way to change it.

I'd use a Solar Roof Jack https://solarroofjack.com/ but none of the pipes are plastic, and it seems inelegant to have pipe
hidden under a solar panel, when the attic route is just an angle away....

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