I just got my permit to do the basement. I am putting a full bathroom down there and breaking into the slab. This bathroom is right on top of the final clean out before the main 4″ pipe hits the wall and goes out under the street.
The building inspector said that as long as I have 2″ for shower and sink and 3″ for the toilet I do not need to worry about venting. He was pretty confident that since the main 4″ ultimately goes back through the house and up to the roof I’d be ok. I think this may be called a “wet vent” but that unless I’m doing a lot of draining on the second floor at the same time it’s really no big deal (and even then the fat pipes I’m using will be ok). He said if it ends up posing an issue I could get a “cheater vent” (i.e. mechanical unit) attached to the drain on the sink and I’d be good.
Am I good to go? I have to say accessing the main vent stack from this part of the basement may be a pain which is why I’m relieved I may not need to bother. All I’d end up with is the three lines hooking into the main one in the ground only–no wet wall to speak of–and I’m done.
Replies
Sorry about how harsh this is going to sound, but he's an idiot.
Wet venting should only be done when the upstream fixtures are on the same floor & limited to 1 & 2 unit fixtures up to a total of four fixtures.
I'm not a fan of mechanical vents as all mechanical things will fail by design, but sometimes there is no other choice.
Remember short cuts equals a short lifespan.
Unfortunately, like Plumbbill said, wet venting can only be done in very limited circumstances. Doing things the way he suggests may satisfy him, but wouldn't meet our plumbing code. Flush the upstairs toilet and the water in your basement one will be dancing. Is it really that hard to tie into the vents upstairs?
What your BI suggests won't meet code, but it will work. Here's why:
The only way the traps could be siphoned (negative pressure exerted on the trap seal) or that they could burp (positive pressure on the trap seal) is if the 4" line were running so full that there were no air space in the top half of the pipe.
Since this is not an apartment with many bathrooms and many occupants using the 4" line, there is no way that your family could ever load the 4" line so full that it would lose its capacity to provide venting action that will protect the trap seal. This is especially true since the place where you're tying in will be far down the horizontal section--the flow has plenty of length for it to flatten out, thereby running low in the bottom of the 4" line.
The way you connect the new trap arms to the 4" will be important to assure that each trap arm has access to the air in the top half of the 4" line. First of all, it's best to make individual connections to the 4", if you have the space. For the wye's that you use to connect into the 4" line, be sure to lay them almost flat, rather than rolling them up very much. This is because you want the flow to enter the 4" as smoothly as possible (reduced "hydraulic jump" is what you're after), and so that the top half of the 4" line maintains as much air space as possible.
For the sink drain, it would be a good idea to have an air admittance valve (mech. vent) in the top of the vertical line that serves the sink. That way, it will always be accessible, because it's bound to fail sooner or later. Changing it is about a 30-second job if you have good access.
The reason the sink needs the vent is because the flow line (or "weir") of the trap is above the point where it can get access to the air in the top half of the 4" line, and, without a vent, you would be making an S-trap, which is prone to self-siphoning.
The toilet always self-siphons to work properly, and then refills the trap seal as the tank refills. The tub or shower will not self-siphon because they will have access to the venting action of the top half of the 4" line, since the traps are below grade. You should set the trap for the tub or shower deep enough so that the trap arm doesn't need to have an offset downward to reach the level of the 4" line. This is because you would be making an S-trap if the weir of the trap is higher than than the top half of the branch line where it enters the 4" line.
Wouldn't having the wyes on their sides work against the way you are suggesting the venting will work. If as you suggest the 4" line will never be completely full, how will the wyes have access to this air if they are not on the top of the pipe?
On a more general level: all sorts of unvented plumbing may work by poaching off another floor's vents. Completely unvented plumbing may also too in fortuitous circumstances, but is it a good idea?
Thanks for the helpful responses! I am frankly not sure exactly where the main stack is to even hook it up to. I am going to take another gander tomorrow and unscrew a clean out which I am hopeful is leading to the main stack. If it is I may go that proper route.If it's not up to code but would otherwise work and, importantly, pass inspection, I may take that cheaper route. I am concerned about filling the concrete back in and THEN finding out I should have vented it, though, so hopefully I'd be able to figure that out pretty well before hand, should I take this cheaper route.
I am sure not trying to cause you more work - I know renovations are hard enough without additional problems being heaped on, but no sensible person would suggest plumbing a bathroom without venting it.
I have looked again and what I _think_ is the main stack has a clean-out that in fact was glued shut. It has a cleanout with the square end to attack to when unscrewing but it's been glued/caulked shut; I cannot open it. This is similar on most of the clean-outs in fact, although a couple of them (the main on the floor and another large one) are not glued shut. I don't know why they glued them, but they won't open now. I'd have to hack up the clean out off and hook it up again and I'm not 100% positive this is the main stack. Before really going to town trying to open them I mentioned what looked like glue to the BI and he said it wouldn't be glue but rather a wax or something, but it sure looks and feels like glue and acts like it :)Is it a proper test that if I do go with the wet vent approach I can hook my pipes up and simply dump a huge tub of water into the various pipes and see if they drain properly? I assume that would be suitable and then if I find out that they aren't I then could put another effort into the venting solution (or even hire a plumber, but I hope not)?EDIT:http://publicecodes.citation.com/st/ny/st/b400v07/st_ny_st_b400v07_31_sec002_par001.htm"P3102.2 Vent connection to drainage system. Every vent stack shall connect to the base of the drainage stack. The vent stack shall connect at or below the lowest horizontal branch. Where the vent stack connects to the building drain, the connection shall be located within 10 pipe diameters downstream of the drainage stack. A stack vent shall be a vertical extension of the drainage stack."I barely know what I'm reading but if this is the case perhaps the wet venting approach, given where I'm doing it in the main drain line and very close to its final exit out of the house lends itself to this idea that the venting will work ok...?BTW here is the drain:
http://i897.photobucket.com/albums/ac177/Skoorb100/drain1.jpgand inside:
http://i897.photobucket.com/albums/ac177/Skoorb100/drain2.jpg
Edited 10/24/2009 7:57 am ET by Skoorb
Your situation occurs frequently in many different tasks during renovations. Venting requires you to open walls you would rather not open. Perhaps removing a wall to put in a beam would mean carrying posts to the foundation that would necessitate you to open further walls. New electrical outlets in a kitchen would be simpler if you could just come off an existing one in an adjacent room rather than fish wire all the way to the panel. That is the nature of the beast.
I think you got very bad advice from your inspector and it has set you off on a path you shouldn't be pursuing. There are no field tests that will allow you to anticipate whether your bathroom will work effectively without venting any more than there are for loading beams to see it they stand without posts, or plugging in all your appliances to see it your new kitchen outlets make the grade.
Sorry, but that's the hot and cold of it. You need to provide venting for the fixtures.
Having the wye's on their sides means that their centerlines will be at the same level as the 4" centerline. This way they have access to the air in the top half. But just as important is the fact that the flow from the branches will enter the main stream smoothly and running free and fast.
Anytime a branch dumps into the upper part of the main line, flow energy is dissipated in the process (hydraulic jump or turbulence), and this slows the flow. Also, if the the branch discharges into the top half of the horizontal main line, it can create a sort of temporary curtain of water that interferes with the air movement in the top half of the pipe.
"On a more general level: all sorts of unvented plumbing may work by poaching off another floor's vents. Completely unvented plumbing may also too in fortuitous circumstances, but is it a good idea?"
What I suggested in my original comments are ways to create the fortuitous conditions that will allow his system to work trouble-free, and will save the expense and difficulty of opening up a wall in the upper level of the house.
around here a wye laying flat on a horz line will get you red tagged. they want it entering the top of the pipe. so as water goes by it cannot cause a suction.the older i get ,
the more people tick me off
"around here a wye laying flat on a horz line will get you red tagged"
Neither of the nationally-recognized codes (UPC or IPC) has such a prohibition. Sounds like you're the victim of an inspector's pet idea.
Horizontal drain lines are sized in the codes to normally run half-full, even when loaded to the maximum drainage fixture units allowed. Thereby, the centerline of a wye branch, even if it's smaller than the pipe it connects with, will be at the same level as the centerline of the parent pipe; both will have their top half above the flow line.
Anytime a branch line enters the main pipe in a way that creates a waterfall effect, the resulting turbulence in the line dissipates the flow energy and actually slows the flow. Ideally, horizontal flow should be fast, free, and flat, that is, with as little hydraulic jump, or turbulence, as possible.
This is why the IPC doesn't allow a horizontal branch connection within 10 pipe diameters of where a drain changes from vertical to horizontal--the 10 pipe diameters' distance allows the flow to flatten out into the bottom of the pipe before another source of flow joins it.
I deal with the UPC.
A wye tying to drain lines together on a horizontal plane is fine by any code I'm sure, but having that wye serve as the vent connection it must roll off above the centerline of the waste pipe that it is serving per the UPC.
Exactly right.
The code requirement you refer to addresses the way to begin a wet-vented section, not the way to connect to a wet-vented section.
However, my suggestion was in response to the OP's original post where he asked if what his BI recommended would work. (And, no question about it, what he recommended would not meet the UPC, the IPC, or NY state code, but it would work.)
In that case, the wye connection would be the junction of a trap arm to a wet vent, because he would be using the 4" main line as a wet vent. Again, not to code, but it works because of the oversizing of the main line, which has adequate access to vents upstream of the new bath.
As we all know, the trap arm needs to have access to air, or connection to the vent, at a point that is not lower than the weir or the trap--otherwise, we've made an S-trap that's prone to self-siphoning.
By rolliing the wye up, he unavoidably raises the weir of the trap higher than the point where the trap arm connection to the wet vent (the 4" line) can first get air.
Finally, his case is one that calls for using principles of venting and flow, rather than the prescriptive requirements of the code. I believe his BI was doing just that.
Thought I'd post where I'm at now. I've been sledging into the concrete. I am fairly committed to the layout of the bathroom as stated here because it works well with the confines of the basement. Also, unfortunately, the distance between the final clean out and wall is so short I don't believe I can easily get into it, which is why I have what I have here:http://i897.photobucket.com/albums/ac177/Skoorb100/piping_branch.jpgDo you see any problems with it? Dark green is 3", light is 2". I'd have Y connectors for the most part with a proper "directional" tee where the 3" hooks into the 4" main line so that an auger would continue down the line as it should.ORhttp://i897.photobucket.com/albums/ac177/Skoorb100/piping_branch2.jpgMain problem with this last one is the concrete "ledge" in the middle may get a bit thin; I don't want all the stone collapsing away from under it, as it tends to do. Also, I'm not sure if it's allowed to have such aggressive angles in the pipes (even though any tees would be of the directional kind.EDIT: These directional things I'm talking about are properly called sanitary tees. Apparently just for connecting horizontal into a vertical. So, that won't do. Which means I need either a WYE, but its angles don't please me, or perhaps a combination tee (http://www.idealtruevalue.com/servlet/the-30682/Detail) would be code-compliant and functional?Of course, my wife asked the obvious. Why not drain the sink into that clean out and leave a clean out cap in place. I don't know that there's the room to do that without destroying that entire joint but even if there was the sink would then be separated from the toilet and bath branch, which would technically leave them unvented.
Edited 10/28/2009 9:43 pm ET by Skoorb
You're right about the proper type of fitting to use for horizontal-to-horizontal drain connections: use the kind (combination Tee-Wye) in the 3rd picture, or you can buy a wye and a 45-degree elbow--two fittings that give you the same angle, but are probably cheaper and definitely more versatile. Having the 45 as a separate fitting allows you to "stretch out" the bend, which sometimes makes it easier to get where you're going.
Your pictures are very helpful, and it appears that the existing drain is very shallow. This means that it will be difficult to patch in small sections of concrete in around the new lines because the pipes will be so close to the surface that the new concrete will crack in lines that follow the pipes. I think you will find it easier and sturdier to break out the entire area that encompasses your plumbing and patch it as one continuos surface. You could lay a steel wire mesh blanket over the whole area to help keep it from cracking, and pour the new concrete over that.
As for the configuration of piping, either one will meet your code if you install the AAV on top of the vertical riser that will drain the sink. Bring the riser up, either through the floor of the vanity cabinet, or inside the wall behind the vanity. At a height of about 20" above the floor, install a sanitary tee (not a wye or a combination T-Y) so that the horizontal branch of the tee has its centerline at the 20" height. This horizontal tee will become the trap arm for the sink. Keep it off to the side of the sink drain about 4" so that you don't crowd it too close to the sink drain, which can make it hard to fit the p-trap in.
The top of sanitary tee will be for continuing up another 4-6" to the vent termination, which, in this case, will be the AAV. It will be exposed and accessible within the vanity. The doors of the vanity will provide plenty of air leakage to allow the AAV to suck in air as needed, but your BI might still insist on some kind of grille in the vanity.
Be sure that the AAV you buy is labeled to meet ASSE standard 1051. There are some that are sold that aren't listed and labeled to meet the standard
Thank you!I ran through the fittings at HD today and was unable to find a combination tee. In fact, their fitting selection is not great. I believe Lowes has a much better one, but I can of course create my own combination tee with a wye and 45, so I'll do that. I plan on using the all-rubber (non-shielded) Fernco couplings to hook that new 4X4X3 wye onto the main line, assuming I cannot rebuild everything at the clean-out.You are correct about the dept of this drain, basically they had the drain on top of the rocks, then the vapor then the 3" of concrete, so if I don't recreate the entire ensemble around the clean-out I will be left with fairly thin concrete.
Ain't no stoppin' you now.
Good luck!
Had the inspector over for a chat. He said that I could take advantage of that cleanout and drain the sink to it and leave toilet/shower alone but his preference is to do what we have here in the pic now:http://i897.photobucket.com/albums/ac177/Skoorb100/layout.jpgMakes sense and should make it much easier to drain the pipes properly as the longest run is only 6' or so.He often used the term "I'd prefer to see" so I took the hint on all those; I have his blessing on this layout.He also said he would think about just busting up all the concrete and not trying to snake thin trenches through it. Got lots of hammering ahead of me.
I would go with what he suggests. It will work fine, and he'll be sure to pass it.
Breaking the concrete out in the whole area will not be much worse than trying to break out channels because once you break out the channels, the in-between stuff will break out quite easily in fairly large pieces. Some of your hardest work will be to haul all the broken stuff up and out of the basement. I'm guessing you'll end up hauling about 20-25 5-gal bucketloads out of there.
This is where you hope that the original builder was a stingy, lazy bastid and the floor's only 2-3" thick, instead of 4-6".
A strong nation, like a strong person, can afford to be gentle, firm, thoughtful, and restrained. It can afford to extend a helping hand to others. It's a weak nation, like a weak person, that must behave with bluster and boasting and rashness and other signs of insecurity. --Jimmy Carter
Based on what I've heard from neighbors I expected he had gone cheap on the concrete and in fact he had; it's only 3 inches thick ;)I have all the fittings I need, but the guy at HD who is a licensed plumber was emphatic that I use a 4" as the main branch when connecting back to my drain and then a customer of his who's also a plumber was saying the exact same thing. That seems like expensive overkill to me, especially since I think the other toilets in the house are only on a 3", the inspector is saying 3" is fine, and I cannot find any combination of searches on google where anybody has said 3" is insufficient for a residential toilet, so I plan on sticking with 3".
Ugh, cracking concrete has it such that I am now finished removing concrete. But the entire bathroom (almost) is now completely excavated. The cracks kept going to the wall. I figure I have about 25 square feet now and 3" deep. Quikrete at 60 lb bags will require 17 of them or ~$125 (?). I should have gotten that rented wetsaw afterall, perhaps.Given that I'm no longer filling a thin trench and instead a pretty large area is this something I can reasonably fill in myself or should I hire somebody? If I transported all the concrete there I suppose I'd just be using them for pouring of it and leveling...One very large chunk in particular is still in place (bottom pic), open on all sides with a crack on one edge. If I open that crack up enough to fill in, could I leave it there; basically jigsaw portions of the slab back together with concrete in super large cracks (so it would go all the way down)?http://i897.photobucket.com/albums/ac177/Skoorb100/concrete.jpg
http://i897.photobucket.com/albums/ac177/Skoorb100/concrete2.jpg
Edited 10/30/2009 9:42 pm ET by Skoorb
I believe you should break out the peninsula that's left, following the crack that extends from the cleanout riser back to the wall.
The patch will be at its strongest when its shape is as near round as possible--not perfectly round, of course, but near.
Also, my calculations say that, if you end up with 30 sq. ft. to fill @ 3" deep, you will need only 7.5 cu. ft of new cement. (Each sq. ft. = 0.25 cu. ft. if it's only 3" deep.) The Quickcrete website calculator says you'd need 17 bags for 30 sq. ft. @ 3" thick.
This is do-able for the DIY'er. I recommend that you do NOT try to mix in a 5-gal bucket. Buy a plastic mortar-mixing tub from HD for about $10, and mix using a hoe. (No jokes, please, about mixing with ho's.)
By the time you've hauled all the rubble out, all the bags down, and mixed, placed and finished all the mud, you'll be a new man. The sledging you've done so far shows you can do it all.
Thanks, I will remove that chunk.I'm thinking of getting either the high-strength concrete or the quikrete crack resistant. Either one will increase my cost by only about $15. I figure they may assist with trying to prevent a crack along the seam as it connects to the old concrete. I will dampen that up a lot and "brush" it in regardless.Do you think I can mix 15-20 of the 60 lb bags fast enough? I am going to have another guy over. We could either do that mortar bucket + wheelbarrow or maybe two bags at a time in the wheel barrow.Not sure if I could screed by hooking a ledge to the wall to make scaffolding to kneel over or if it's ok to just do it in some boots. It's only 3" thick so it shouldn't really flood out all that much, then I'll float it on an extension.Quikrete has a cement adhesive used as a preparatory step when adding self-leveling compound. Would this brushed on the existing slab edges be of help or harm? The good thing is my sledging has pretty much undercut all the edges so the surface area is pretty good and it's quite ridged/rocky.
Edited 11/2/2009 10:08 am ET by Skoorb
With a helper, you can definitely mix fast enough.
You won't have conditions that speed up curing. (No wind, no direct sunlight, no high outdoor temp) You will have plenty of time.
Additives that bond the new to old are good.
Your patch will almost certainly crack where it meets the old, but it should not tend to lift because of the undercut you mentioned. (That's at least one good feature of sledgehammer-breaking.)
Attach a screeding ledger to the outside walls and make a screed stick with an ear, or projection, on one end that will ride on the ledger, and the other end on the existing concrete.
Since this cement is resting on top of a vapor barrier (normally concrete is on top of something porous and dryable) for curing I had planned to leave the dehumidifier off for a few days. Should I mist only? If I put plastic over the top it may end up staying moist for a really long time...
I'm not an expert on concrete, but in my experience doing the kind of small patching that you're doing, I would say that the vapor barrier underneath will slow the curing to allow very high strength and to afford you plenty of working time. In fact, I think you will find that it will be a long time before you can do your final toweling without bringing up a lot of soupy slurry to the surface.
And, of course, once the final toweling is done, you could cover the patch with plastic, but I don't think it's really necessary.
I am good to go now, got the plumbing 100% finished and inspector yesterday said to fill it in. I am doing it tomorrow with quikrete crack-resistant concrete. I am still unsure whether I should use any rebar or not. Not for most of the patch, but should I use it to attach the old to the new cement? I have the rebar purchased along with an anchoring cement and was going to drill 4" holes into the existing slab every 18" or so. Then rebar only on the edges. My only concern is that if I am going to end up with a crack along the old/new line anyway, this rebar may interfere with that but not in a desirable way; i.e. cracks may end up elsewhere or something instead.
I would strongly recommend borrowing, renting, or buying a concrete mixer. I bought one off of Craigslist for $100 (an old Gilson with a Baldor motor, angle-iron frame, no wheels) and it's big enough for me to do two 80 pound bags at a time. I could probably do more, but two bags works well for me. Each bag takes a gallon of water. I use an empty milk jug to measure - no guesswork involved. With a helper, I can mix and place two 80 pound bags in about 10 minutes. Depending on where I'm working, the concrete gets moved either by wheel barrow or 5 gallon bucket. The nice thing about the mixer is that it makes concrete work pretty easy - at the end of the day you're not tired out and your hands don't have any blisters from mixing with a rake or a hoe. If you're within driving distance of north jersey, you can borrow my mixer.
-BK
Edited 11/7/2009 3:52 pm ET by bk24
With my limited experience doing a patch of your type, I would say that, so long as you've compacted the sub-grade well, you could pour without re-bar.
However, I seem to remember a comment in one of your early posts where you mentioned that the basement slab is not connected to the walls--does this mean that you have expansive soil underneath?
I hope someone with experience in your region can answer you better than I.
It seems to me that re-bar could not hurt, and you're set up to do it.
Wouldn't fly here.
OK, 12 feet away along the same wall is this:http://i897.photobucket.com/albums/ac177/Skoorb100/option.jpgAbove it is the washing machine and also a sink and toilet. Is there anything to be done with this do you think? From what I can tell the venting for these fixtures are all in the walls; I still see no accessible stack anywhere, with zero thought by the builder put into somebody actually finishing the basement, it would seem.EDIT: Here is a closeup of it. I'm wondering in fact if this is a vent that I could tap into? We have here the 3" for the toilet and then a 2" with the vertical 1.5". Everything I see in the basement is 3 or 4 (main line) or 2" so is there any way to tell if this vertical part here in the close up is in fact a vent and if so I could tap into it, couldn't I? It may be what the toilet just above this assembly is using.http://i897.photobucket.com/albums/ac177/Skoorb100/vent.jpgEDIT #2: Actually that 1.5 is definitely the drain for the sink. Thus that 2" line would HAVE to be the vent, wouldn't it? Unless that toilet simply isn't vented since its 3" pipe is directly accessed through the floor. Makes sense, right? In any case, I followed back on that 2" line and got its waxed (they are wax ;)) cap open and it is the only line I have so far opened that does not have some kind of a sewery slime and goo on everything. However, I actually believe it's the drain for the washing machine as it does have a tiny bit of moisture on it. I opened up another one that seems it should be in the spot for the main stack, it's 3". I have yet to be able to run all the fixtures in the house (people sleeping), but it also is lacking the goo but DOES have a little bit of dribble and "bug stuff" in it when I open the cap. Would a vent typically be kind of dirty like that? Like I said, it looks nothing like the definite-drain pipes in the rest of the house...
Edited 10/24/2009 3:10 pm ET by Skoorb
I have to agree with most of the posts, you need to vent the fixtures. Most codes will now allow a AAV to be the only vent with a toilet involved.
Most areas that allow wet venting will not allow it with fixtures above, your call.
"If you don't have the time to do it right, where will you get the time to do it over"
"Unless that toilet simply isn't vented since its 3" pipe is directly accessed through the floor. Makes sense, right?"
In a typical three piece bathroom the toilet is not separately vented but is wet vented.
"Would a vent typically be kind of dirty like that? Like I said, it looks nothing like the definite-drain pipes in the rest of the house..."
Remember that the vents go up through the roof and are exposed to any rain and debris that falls so yes you may have found one. Wake everyone up and run some water.
OK I've run all the drains upstairs and can unequivocally say that there is truly no vent access from the basement. I find that a real shame considering the house is only four years old and not an entry level. The builder made it a 12 course (standard+1) but no vent stack access.I realized that the vent accesses outside so when it rains it's going to get wet but I ended up with a face full of water when one of our toilets upstairs was flushed, so that wasn't going to cut it ;)Truly every pipe that can be seen from the basement has fluid moving through it.I very much appreciate the time y'all have put into opining on this topic. I want to go past what the BI said just so that it's "done right" (honest), but if I'm going to have to start busting up walls looking for the vent stack to meet a requirement that he's not looking for and there's a great chance things will workout without it I may have to give up. I'd run a second stack but since I believe they all have to go up through the roof, that's a good bit of work, too.
Any went that you can access in the basement will likely have a fixture above it, dumping onto it, in other words, a wet vent, so you will not gain anything by tying into it.
Tying into any dry vent in the ceiling of the basement will actually be a code violation, since vents (wet or dry) must be joined together at a point at least 6" higher than the flood rim of the upper fixture, which would mean opening up a wall in the upper floor.
Only a vent that rises from a basement fixture would be any help to to you as a point to tie in your new vent, and it appears that no such vent exists, if I understand your description.
Also, the NY code info that you included in one of your posts says plainly that you could use an air admittance valve (mechanical vent) to vent the bathroom group, since the house has at least one vent that terminates thru the roof. So you can meet the code of your state by using the AAV if you choose. Just make sure it's installed according to the manufacturer's instructions, and any applicable NY code requirements.
So talk me through this. If the NY code allows him to use an air admittance valve for the bathroom and avoid wet venting then a) The valve would have to be located 6" above the level of the sink (perhaps behind the mirror?) and b) the fixtures would have to be plumbed and vented as a group with a single 3" connection from the WC into the 4" line
I also just saw that "in some cases" for AAVs it should be placed above the flood level of the sink. However, the BI drew out a diagram to me yesterday and I'm pretty sure that if I read it right the AAV was going to sit hidden in the cabinet similar to how this guy has his:http://www.handymanhowto.com/wp-content/uploads/2008/08/studor-sewer-valve-under-kitchen-sink.pngIn this manner I'd have my sink and shower hook up to the 3" toilet, which in turn hooks to the 4" and the AAV is an "after thought" if I need it; it's not like each of these three fixtures will be individually vented to a main line which has access to an AAV instead of a normal vent stack.Certainly I'd double-check on the AAV for the sink and whether the pic above is good or it would have to go behind the mirror, for example.I'd take some quick vid of a tour of the pipes in my basement but I fear I'm already bordering on psychiatric with the obsession of this :DEDIT: http://publicecodes.citation.com/st/ny/st/b400v07/st_ny_st_b400v07_31_sec014_par003.htm"Stack-type air admittance valves shall be located a minimum of 6 inches (152 mm) above the flood level rim of the highest fixture being vented."So there you go. I assume a cabinet is sufficiently ventilated, but it isn't 6 inches above, so I'll need some way to hide that.
Edited 10/24/2009 11:13 pm ET by Skoorb
"and the AAV is an "after thought" if I need it"
Wait now, we are discussing how you vent your fixtures not if you need to. Everyone is pretty clear on that. If you can't tie into an existing vent your AAV is your dry vent. It isn't an extra, it's what make the system work and as a bonus meets your code.
You are probably right about it being allowed up under the counter. That is how they are installed on kitchen islands.
I probably misunderstood the BI. I agree with you, it is not an "if I need to vent". I would built it in from the start.
Good luck with the project. Enjoy your new bathroom!
Thanks :)Do you have any opinion, given that I actually have this choice with an AAV, on whether I should drain to the wall (http://www.oatey.com/aav_public/resources/photos/6_sink_app.jpg) or the floor (http://www.wrighttouchplumbing.com/media/studortocode.jpg). If both are to code is one or the other easier to deal with later?
Going through the floor leaves you with a hole in the base of your vanity which is hard to clean and limits storage. Go through the wall about 12" off centre of the sink so you can run a 90 off the bottom of the sink drain and have your trap parallel to the back wall leaving you more clear space for storage.
AAV's do not have to be located 6" above the flood rim; they are required to be 4" above the trap arm. (The branch of the sanitary tee is where the trap arm begins.)This allows the AAV to be inside the cabinet and to be always accessible and visible.
The 6" above flood rim requirement refers to the point at which dry vents may be run horizontal, and the point at which two vents may be tied together. The reason for this is in case the drain becomes blocked, water and gunk will rise in the line to the flood rim of the fixture; if there's a dry horizontal vent lower than the flood rim, the gunk will be left behind. lying in the horizontal portion. This can lead to vent blockage over time.
Pardon my long-windedness on this if this is stuff you already know, but others reading this post may be interested in the reason behind the code requirement.
The new bathroom group can be tied into the 4" with a 4 x 3 wye, and the group can be vented with the AAV under the sink. The whole arrangement will meet the NY code. which appears to be the IPC with NY amendments.
"Pardon my long-windedness on this if this is stuff you already know"This thread has been a great help to me :)I was perusing Stanley's book on plumbing at Lowes yesterday and it talks of AAVs along with some pics. In one case it showed the AAV venting "between" two fixtures; i.e. kind of like these fixtures would have their own vent (per conventional approach) but instead of up to the stack it would go to the AAV betwen them. In another pic it showed the under the sink approach. In the first neither fixture relies on the other, but with the under-the-sink approach if the sink somehow got completely clogged the other fixtures relying on it for venting would no longer have venting. In practice I have no idea if it's worth worrying about.
Anytime a single vent serves more than one fixture, with fixtures entering at different levels (a "wet vent") there is the possiblity that a drain blockage of the upper fixture could cut off venting action for the lower fixture(s).
Not to worry. If the upper fixture, or any fixture, is blocked, you'll know it. Once you clear the blockage, the vent is back in order.
But there is some non-trivial danger that the process of clearing the clog will simply push it into the vent tee and clog that.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
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But there is some non-trivial danger that the process of clearing the clog will simply push it into the vent tee and clog that."
That is a remote possibility, but the possibility does not arise due to the fact the he would be wet-venting fixtures below; the same thing could happen even if there were only one fixture being vented.
>>>Tying into any dry vent in the ceiling of the basement will actually be a code violation, since vents (wet or dry) must be joined together at a point at least 6" higher than the flood rim of the upper fixture, which would mean opening up a wall in the upper floor.<<<
That is not correct, a dry vent (i.e. vent stack) can be tied into as long as the specific vent is run 6in. above ITS flood level rim. If you think it out what would you do in a hundred story building?, wouldn't be any reason to run vent stacks
"If all else fails, read the directions"
"That is not correct, a dry vent (i.e. vent stack) can be tied into as long as the specific vent is run 6in. above ITS flood level rim. If you think it out what would you do in a hundred story building?, wouldn't be any reason to run vent stacks"
In the OP's situation, he would not be tying his new dry vent into a vent stack, he would be tying into an individual vent at a point lower than the flood rim of the fixture it serves. Such an individual vent is subject to being flooded if the drain that it serves becomes blocked. If the tie-in were lower than the flood rim of the upstairs fixture, the lower vent would be flooded, and any horizontal portions would have debris left behind that would not be washed out. This will eventually grow mold and reduce, or even cut off, the venting action.
In your 100 story example, individual vents, or vents that serve a group of fixtures on one of the floor levels, must tie into the vent stack at a point 6" above the flood rim of the highest fixture served by the individual vent, as you say. However, the base of the vent stack itself must tie into the waste line at a point at least 6" above the flood rim of the fixtures on the lowest level. This ensures that the vent stack will always be dry, even if the main drain line were to become blocked, and it ensures that no connection into the vent stack will be arranged in a way that might cause the vent stack to be flooded.
I think the way we are phasing is causing the mis-understanding."If all else fails, read the directions"
Yes, I agree.
Terminology is often what gets in the way of understanding.
Vent stack; stack vent; waste stack; waste pipe; trap arm; wet vent; dry vent; fixture drain; branch drain; building sewer; building drain, etc, etc, etc.
And the worst part is, the codes (UPC, IPC, and various State codes) don't always agree on what each of these terms means. Then you get individual jurisdictions and inspectors that all have their own ideas of the meanings and how to interpret their application to a particular job.
I have an old (1967) edition of the Southern Standard Plumbing Code that has a feature I really like. Its chapter 2 is titled: "Basic Principles", which consists of 12 basic principles that define what we're trying to accomplish with the rules of the plumbing code. All requirements of that code every other plumbing code really just come down to those same basic things.
Knowing things like that helps an inspector to know how and when to "bend the code" in a reasonable and safe way in order to address situations not covered adequately in the code, or when special conditions make it impractical to meet the letter of the code.
A co-worker insists that I get radon testing because of this. When I bought the house in 2005 I had it radon tested by the inspector (he left it there for a couple of days I think, running). I have no idea what the number was but it "wasn't a concern". I do have that "floating slab" foundation with the 1/2" between the slab and wall, which goes down to gravel, so I can't imagine I'm terribly disconnected from anything emanating from the ground anyway. However, if I break through the vapor seal, and even fix it up a bit, I guess what's how my co-worker is insisting too much radon _could_ come in.Is this really worth pursuing?
Radon? Don't get me started.
But if you're really concerned, just make sure you'll be able to provide good airflow to dilute any real or imagined accumulation of radon when you're done.
They have mail order kits for about $10 that you can do a 3 day radon test in your home. I did this when we replaced all the windows in the house because our bedrooms are in the basement.
I miss the old days when the plumbing code was 10 pages and all you had to remember was 5ft. off the stack, and no individual vents! If you read that chopped off post of mine I don't have a clue how that happened, must be those Breaktime gremlins! ;)
"If all else fails, read the directions"
I've got a copy of the 1925 plumbing code for the State Oregon pinned to my office wall.
It's one page, and says that sewage may be "discharged into a river or stream where such is not in violation of any city ordinance or law of the state."
Progress has many faces, some prettier than others.
rdesigns, are you sure that isn't a copy of the 2009 Beijing plumbing code? ;)
I think theirs has an additional requirement for high-density population areas:
Before emptying the bucket out from an upper-story window, you have to shout out a warning to pedestrians below.
LOL! Brought back childhood memories of peeing out the upstairs window of our cottage when I was too lazy to get out of bed and go all the way to the outhouse.
It was when India and China modernized they adopted that code! ;)
"If all else fails, read the directions"
I think that the way we are phrasing may be causing the mis-understanding.
"he would be tying into an individual vent at a point lower than the flood rim of the fixture it serves."
Of course I agree that you can't do that.
What I take exception to is he can't tie into a DRY vent if he found one in his ceiling.
When I was roughing in future fixtures in a basement I always left a 2in. capped DRY vent in the basement ceiling, if the OP found one of them he would be good to go, these vents were tied into the stack vent, hope this clarifies what I was saying.
"If all else fails, read the directions"
"What I take exception to is he can't tie into a DRY vent if he found one in his ceiling."
I agree, IF the dry vent originated in the basement. That way, even if the fixture drain that it served in the basement were to become blocked, the backup could not reach any higher than the flood rim of the basement fixture.
The OP stated that he definitely tested all vent lines located in the ceiling, and confirmend that every one was a wet vent from the floor above.