Here is a minor little spiff I am having with my partner. It regards which plastic pipe type to use for the under-the-slab building sewer line.
We fall under the NY state plumbing code, which is pretty much IPC. We are way upstate rural, building inspectors are part-timers, and plumbing is never their concern. Never. Furthermore, NY has no certification nor licensing requirements for plumbing contractors. You get what you get.
In all I have ever seen and had done, Sch40 PVC is used. My partner and his regular plumber (I’ve not used the guy) say all they have ever done is with SDR35 sewer PVC.
If you are into plumbing and you are still with me on this topic, you know the difference. If we’re looking at 4″ pipe, and that is what Mr. Regular Plumber says he always uses for the main sewer line under slabs, Sch40 has a 4.500 OD, and a wall thickness of 0.237 inches. SDR35 pipe is 4.215 OD x 0.120 wall. Of course, it’s cheaper, which I suspect is the reason Mr. Regular Plumber “always” uses it.
A full line of fittings, including wyes with reduction, closet bends, sweep 90s, etc., is available for Sch40. The fittings available for SDR35 are very basic and limited.
My thinking is that you use Sch40 inside the building, under the slab, do glued joints, and transition with an adapter coupling outside, and go with SDR35 with bell-end slip joints to run to the town main or to the septic tank. You DON’T want to be glued up, outside.
You want your underslab lines to be darned permanent, and able to withstand some rough roto-rooting, if necessary. The glued joints and the wall thickness (SCH40 about twice as thick as SDR35) gives one the factor one needs.
Furthermore, I think is is a code violation to use SDR35 inside. I know the UPC doesn’t permit it, but the garbled way that the NY plumbing code is written prevents me from knowing for sure.
We’ve agreed, my partner and I, and will use Sch40 inside, but I cannot understand why we had so much discussion about it. His Mr. Regular Plumber is going to do the work, but he is not convinced, and will likely continue his practice of using SDR35 inside, for other work. For us, though, he’s using white, not blue.
Edited 6/1/2007 9:11 am ET by Gene_Davis
Replies
You're making me glad I live in a place where this stuff is closely regulated. The SDR material is not commonly available and would never be used for plumbing a house.
Gene,
Here (Or.) schedule 40 ABS or PVC under slab.
Here (WI) it's sked 40 all the way to the street. The only place the thinner wall sewer pipe can be used is from a septic tank to the soil absorption system (seepage bed or drain field) on a non-pressurized system. It doesn't make any sense to use the cheap cr*p any place there's a potential for using a snake - there's too much chance of breakage.
You said, "Here (WI) it's sked 40 all the way to the street."
Which is why, I guess, SCH40 is available both in plain end and belled end.
Use belled end outside, slip joints, no glue.
I'm thinking, "hey, pard, you wanna use thinwall pipe for the main drain, right? Let's extend that thinking and frame the place using furring strip stock."
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Use glue for every joint. Tree roots will migrate to ANY tiny source of water they can find, which will be at each joint if you don't glue them well. You'll have a constant problem with tree root clogs if you don't seal each joint well.<!---->
We just had to replace the entire line from the house to the taank on a 20 year old system because the non gled thinwall joints were all filled with tree root. Glued schedule 40 is what went in. Been having trouble with it for nearly 10 years.
In the areas that I work in, most of the time you can use sdr35 for exterior sewer, but interior has to be sch. 40. Seems strange That NY has no requirements for plumbing contractors, its always had the reputation of one of the hardest tests around??
"If all else fails, read the directions"
From the engineering/septic side of the table: no way I would allow SDR35 to be used within the building footprint. Usual spec is Schedule 40 all the way to the septic tank, and then they can use the 35 from the septic tank to the leach field. If sewer is available, 5' out from the foundation for SCH40, Fernco rubbr transition/flex coupling, and SDR35 to the street.
I have seen a few mobile home slabs go in with SDR35 under them, and while I don't like it, I can't do anything about it - not my spec. Contractors over here usually know better.
schd 40 ABS and glued here all the way!
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Even in the land of no drip edge, tarpaper, or rebar, it's sch 40 all the way, and we don't skimp on the glue either...80 under the drive<G>. I ain't gonna work for Maggie's ma no more.
No, I ain't gonna work for Maggie's ma no more.
Well, she talks to all the servants
About man and God and law.
Everybody says
She's the brains behind pa.
She's sixty-eight, but she says she's twenty-four.
I ain't gonna work for Maggie's ma no more.
My plumber, not his shadetree plumber, says it is actually detrimental to glue the joints in the sewer line that runs from the building, underground to the main.
I'm told that small amounts of subsurface movement, from frost heave or other inputs, can stress glued joints enough to break pipe, thus my plumber's preference for PVC SDR 35 PSM pipe, belled end, gasketed.
The sewer main running under our road, and mains running all around town here, are large diameter coextruded webwall ABS with foam fill, all belled ends, gasketed joints, no glue.
But everybody knows that codes are at best, a minimum standard, and only for weenies. As always, and of course, you are free to overbuild. Such as framing at 16 inches on center. ;-)
Here it's glued sched 40 under the slab and all the way to the street.
Not to drag this thread off on a tangent but there are actually 2 types of schedule 40 pipe - solid core and cellular core. Anyone know why the solid (more expensive one) would be required?
I believe it has to do with crush resistance, or lack there of depending on how you look at it.TFB (Bill)
Actually there is a 3rd type of pipe. Sewer and Drain, IIRC it is ASTM D-2729.S&D is the same OD as SDR 35 and can use the same fittings. But it is thinner wall thickness.It is interesting that S&D is the only one that specs a crush resistance.But, without buying the spec book, I could never find out exact what that ment and how it was tested. Both S&D and SDR 35 come in solid and preforated versions. And they come with glued connection or with gasketed fitting that use oil ring seals.A couple of years ago I ran a bunch of S&D for ground water drainage..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Matt,
I have no idea why but I do know that the cellular core is what is required here.
"Poor is not the person who has too little, but the person who craves more."...Seneca
around here we can only use the cellular (foam core) above grade... mostly for vent... anything underground... is the std sch 40
p
That makes sense... Maybe that is actually what happens here and I just don't know it. I have a few slab installs going in next week. Guess I'll find out then.
OK - so I thought I'd close the loop here. You probably already knew this, although undoubtidly others here don't, but schd-40 cellar PVC (foam core) is marked "not for pressure" but apparently a lot of people here including the local plumbing inspectors feel it is fine for below grade. On the other hand schd-40 solid core PVC is rated for pressure.
I'm told that small amounts of subsurface movement, from frost heave or other inputs, can stress glued joints enough to break pipe, thus my plumber's preference for PVC SDR 35 PSM pipe, belled end, gasketed.
It may be that, with the extremely cold temperatures which are part of every winter in your area, glued joints do cause problems on occasion.
Edited 5/31/2007 9:34 pm ET by Hudson Valley Carpenter
Here [ Ohio ] it's schedule 40 under a slab and 2 inch is the smallest aloud.
Here (WNY) we usually see cast iron through the basement wall, with 35 outside and 40 inside. I've never seen 35 used indoors, but when I re-did my line to the street (replacing ancient clay tiles), the county specified 35 and came out and looked at it. All for a $2.00 repair permit fee.
Bear
the wall thickness (almost 200 percent thicker as compared to SDR35)
Actually it's either "twice as thick" or "100% thicker". 200% thicker would make it .360 wall.
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