can i use threaded pvc rather than cement?

Plumbing Forums

Help Support Plumbing Forums:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

the13bats

Member
Joined
Mar 19, 2018
Messages
12
Reaction score
0
Location
,
I am working on a 100 plus yo upstairs bathroom,

I needed to replace the old rusty plugged up galvanized sink and tub drains
The catch i wanted to bust as little of the floor as possible,

The rectangle room has the old but good iron main drain toilet on top at one cornor,
Then the other cornor has the sink, the tub drain was T,ed into that sink drain, it goes to the side of the iron pipe behind where the toilet sits on it,

I got all the old pipe out wasnt easy, nice threaded 1.5 hole in the iron stand pipe to connect to, wasn't easy getting that rusted galvanized threads out of there,

My original plan was to cement the pieces and pipe ( pvc ) together as i assembled worked them into their space, in the floor,
But dawned on me with it cemented together it would have to be cut to do any service and getting it all together with some connection out of reach with cement would be a bit tricky, not impossible but difficult.

So can i use pvc threaded fittings on the pvc pipe and just screw sections together, no pressure just a tub and sink drain, is pink tape what to use on the threads, or is there a sealer for this some places will still be cemented together but for example screwing the tub drain pipe into the T with make it so much easier,

If i can do it with some threads fittings it would make it easier and give me peace of mind i could service it without cutting it out,

Okay...clue me in,

Thanks
b
 
You can use tubular trap under the lavatory sink. And the tub should have an overflow face plate to take off if it ever needs cleaned.
 
Adding to what Justin said. Can you put a clean out in the line somewhere if that's what you are worried about.
 
If you are saying you want to put pvc male and female fittings together under your floor then
I wouldn't advise it. You can screw a male adaptor into the cast iron pipe and then just run your
pipe normally to the fixtures. Like Justin said you will have a trap to take apart for the lav and you
can go down the waste and overflow on the tub with a snake.
 
Okay,

Why wouldnt you advise it?
But do advise pvc screwed into iron drain pipe?

So you know more about me,
at the risk of sounding pompous i am somewhat mechanically inclined. I do things ranging form up to code full house wiring to frame off vintage corvette restorations to restorations of antique arcade machines, and building computers from scratch,
But im very OCD ADD and other letters of issues and with this pvc plumbing i see all the threaded fittings made and if its a bad idea to use them its not i dont believe you i do believe you, i just like to know why you feel that way,

Many thanks,
Bats
 
After years of use you are way more likely to develop a leak underground with screwed fittings over fittings with a chemical bond. If it happens above ground, no biggie. It can be repaired with minimal damage.
 
Okay, thank you!

in my case if you missed it, its in a crawl space between 1st and second floors,

I thought hard about it and im going to use both
Glued joints and in a couple other places threaded, like where the tub drain will connect to the sink drain T
i might make changes as i mock it up before install,

But if i do use threaded which is better a sealer or tape seems after a google hunt people are devided....
 
Where I live, almost all plastic pipe fittings are glued. No tubular traps either. I just have a hard time understanding why you want to use screwed fittings at all on drainage. It's more work.

Every threaded joint I do gets Teflon tape and pipe dope.
A few light wraps of Teflon to lubricate the joint, and pipe dope to seal the threads for a little reassurance.
 
So sometimes you do use threaded...

I explained why in my original post,
But to further clarify, i am trying not to tear all the floor out, sure i know that is what a "professional" would insist on doing ( partly to charge more ) but i tend to think more outside the box with stuff, and to me screwing the tub drain pipe in would be easier than trying to get it that 3 feet under the floor to the T all dripping cement making using primer then cement very hard to pull off,

Theres a lot of irony to me for it to be a big thumbs up to use a pvc threaded adaptor into the iron pipe but dont use threaded pvc to pvc
 
You have to understand that you are there staring at the project your working on. Then you try to explain it to someone and have them imagine what you are talking about. Sometimes things get lost in translation as i am sure i would understand it better if i was looking at it. Maybe a few pictures would help.

I would never go to someones house and tell them to demo drywall just so i could charge them a few extra dollars. I may suggest it instead of trying to just patch a section of old pipe, like you have some of it open now why not do it all and be done with it.
 
That's why I wouldn't advise it. And I know nothing about you as posted in #6 and believe me I won't advise you anymore'
 
Never thread dissimilar materials such as plastic and metal pipes together. Recipe for disaster. Always install a short ~3-4" stub out of new metal pipe nipple in a female metal fitting. Use a shielded no-hub coupling, NOT the rubber only Fernco type, SHIELDED only to connect the new pipe stub to the plastic pipe.
 
i know things get lost in type i know people are different personalities,
i haunt a lot of different forums i learned a long time ago some egos are as big as a mountain fragile as glass and my reason for being here isnt to offend anyone with how i present my self nor is it to coddle, im here for help, various opinions and ideas on how to tackle my project if you want to give your opinions many, many thanks if you dont, ill live and my projects will still get done.

Now my remark about a professional plumber would want to, many would insist on tearing out in this case the entire floor to do a job that 90% of the floor isnt in the way, i never said anyone here does that i based that on my personal experiences over 46 years,
Plumbers Like with any hired out work there are good and bad, i am doing this myself because i ran into the bad apples too many times in the past.

And i wasnt clear i am replacing all the drains and pipes with pvc in this bathroom with the exception of that big main iron drain which is in great shape,


SHR,

Please expand, when i said i needed to connect pvc to a 1.5 remail threaded hole in a iron drain i was handed a pvc adaptor, male threads one side and you cement your 1.5 pvc pipe in the other end, im sure you know the piece,

Now if i am understanding you , you are saying dont do that it will cause problems but rather get a stub piece of "metal" pipe screw it into the iron pipe then use one of the shielded rubber couplers to connect that metal stub to the pvc,
I know the parts you speak of,

This bathroom hasnt worked in over 20 years, new copper feed lines were ran back then and capped, so no water in any drain pipes for that long,
We bought the place an over 100 yo former b&b as a fixer upper about 2.5 years ago,

Here is my fear with that so please clue me in,
The reason this bathroom job was started over 20 years ago, was the then galvanized tub drain leaked right through the floor ceiling to first floor, they did repair they first floor ceiling.

The leak was at the tubs drain, the old galvanized removed pipe was still laying on the bathroom floor never tossed in the trash, and it was mostly rusty gunk blocked up but when they removed it you can see the threaded part tore up,

They had replaced only the tub drain pipe with pvc screwed it into the old galvanized sink to main drain pipe at a T where its orginal galvanized drain pipe had been, big mistake, or halfass, because
When i started on it i quickly learned that sink galvanized pipe was also rust gunk plugged up so i desided to get rid of it and go all pvc,

And where that old galvanized sink/tub drain pipe screwed into that main iron drain the threads gave up, i spent about an hour getting the rusty, froze in place busted pipe threads out of that main drains 1.5 threaded female hole,
And the threads in the iron pipe are luckily in great shape,

So in this case pipes rusted badly from inside filled with rust gunk and leaked at threaded unions, i want to avoid that,

So my fear when you say use a metal pipe nipple screwed into that main drain, wont that just rust and leak at those threads all over again?
Please give me a run down clue in...doesnt matter to me if i use a threaded pvc adaptor there or the metal nipple with rubber coupling as you say use i just want more details on it all and least chance of issues and leaks.

Many thanks!
B
 
Last edited:
Matt, you get real, stop changing around what i said so you can get upset,

If you had read what i posted i didnt say "all" and i will expand that to skilled tradesmen not just plumbers do insist on things a certain way to do a given job to make more $$$ i never said "all" and never said you,

If you dont believe that kind of thing happens in this world you are either in denial, lucky to have not experienced it or living in a naive dream land, and i dont mean that as insulting.

For another example i am into classic cars and only about one shop in 100 is any good, this is from over 40 years experience,

If you dont play games like that then you are about one in 100, but no need to get angry because i recognize there are bad apples in this world.

And i do appreciate each and every person who offers help....
 
I don't understand why you keep on posting replies to this thread if you're so dead set on doing it your idiotic way then go ahead and do it instead of listening to the members of this fourm who have helped hundreds of other people with their problems but if you want to be like the many others who decided to argue and do it their way join the club. But if there's one thing that I hate it's when someone ask for help they're given the correct response or they're given the correct way how to do something and then they argue with that person.
If you are so uncertain on how to do this how about you hire a professional to correctly do it wait a minute though they're all scammers that will try to rip you off and charge you a lot of money for doing something you cant sorry I don't know how we can help you anymore...........
 
My dad taught me years ago to never look a gift horse in the mouth. The folks replying to you are professionals, have received thousands of hours of instruction and on the job training.

You made the statement "i haunt a lot of different forums". Well, that told me alot. This discussion is over.
 
I have opened this thread as a last ditch effort, hoping the member understands it is being watched closely. I will tell you from past experience, when a professional decides to move on, he moves on.
 
  • Like
Reactions: SHR

Latest posts

Back
Top