Ok, I am thinking about doing the plumbing for an addition myself and would very much appreciate your help in laying it out. It is a small addition, just 150 sq. ft. spread out over three floors (so, approximately 50 sq. ft. per floor. In the rear of the house (where the addition will be) the basement is entirely above grade. This will be heavy in plumbing as the 2nd level of the addition will have a half bath and the 3rd level a full bath.

My plan right now is to run a 3" stack up one corner of the addition where both baths will tie into. This "stack" (not sure if this is the right term in this application) will tie into the house's main 3" cast iron stack (which currently services 1 full bath). In general, does this work? In order to get this where it needs to be it will require 3 long sweep 90's, is that overly problematic?

Can I run the 3" stack right up and out the roof and use it to vent the various fixtures? I know each fixture needs its own vent, but can I tie it all up together in the attic and have just one protrusion through the roof?

So, can I check dwv sizes?

Toilet - 3" drain, 2" vent
Lavatory - 1.5" drain, 1.5" vent
Tub/shower - 2" drain, 1.5" vent

Am I right on these?

Hi Stubits...

3 long sweep 90s is a bit problematic, but if you install a wye/1/8th combo. fitting with a cleanout in place of one or two of the 90s you should be fine. Otherwise, you will need to install a dandy cleanout after every 3" long sweep... ok?

All DWV sizes are correct as you stated them..

Now, we need to find out if wet venting is allowed in your area (call local inspector if need be). If it is allowed there will be LESS WORK (see picture on left of big picture).

If only individual vents are allowed in your area then there will be a bit more work needed.. see picture on right below.

You will connect vents and run them up to the 3rd floor where you will probably be best to connect the vents into the VENT STACK (now) at about 48" off finish floor and then run the 3" up and out as you noted...

You can also connect the vents in the attic if that is easier...

There is a lot more rules, like pitch for drains and vents, how vents connect together, hanging pipes, drilling joists, where cleanouts belong, how tall to make the vent past the roof line, etc. We can go over that as you fine tune your plan.. OK?

Let me know if you have more questions...

MARK

Mark-

Wow! This is great. Thanks!

We are governed by 2000 International Plumbing Code which I believe allows wet venting, no?

Now, for the 90's, let me try and explain their function and maybe you can help me find an alternative. The 3" stack will run vertically up the left rear corner of the addition. Starting from the roof, it will come down to the ceiling of the basement level where it needs to run horizontally (about 5') to the right rear corner of the addition. At this point it needs to 90 into the existing building where it will run approximately 15' (in a soffit) along the basement ceiling into our utility closet where it will finally 90 back to the left about 2' to tie into the main stack. Complicated, I know. Does it make sense? Effectively this needs to occur because the main stack is on the far side of our air handler, so the pipe cannot just run straight.

Any thoughts?

Hey again...

If there is no other alternative, such as a pipe underground that you think you might be able to get to then you have no choice...

Most important on all these turns is simply going to be to install cleanouts where they can be accessed if needed. If necessary, can also install an access panel for future.

In terms of the IPC I'm pretty sure they allow wet venting, but can't be 100% sure here because even if IPC allows it, it may still not be allowed inyour town/state... need to check with local inspectional services department to be sure.

Keep us posted as you move along...

MARK

Unfortunately the basement is a finished space and going through the floor would be overly disruptive, I think.

So, a "dandy cleanout" is required by code at each 90, right? Before or after? Obviously if it is behind drywall, then I'll need an access panel. The cleanout cannot be drywalled over, I assume.

How would I use the wye/1/8th combo. Fitting you mentioned earlier instead?

Thanks!

Actually, the wye 1/8th combination fitting can almost be used interchangeably with the long sweep 90... as long as you install accessible cleanouts in line.

In fact, the long sweep 90 and the dandy cleanout is probably best in this case as it allows you to snake the drain in both directions of the drain... ;) The end clean out only allows for cleaning in one direction.

See pictures.

MARK

Great.

I could be way off on this, but I seem to remember from another post that wyes are used for horizontal connections and sanitary tees for vertical?

Correct!

Sanitary tees can also be used on the horizontal to pick up vents as long as they are rolled above the center of the drain line... ;)

Ok, great. That's what I thought. I am starting to work this out in my mind and will try and get something down on paper shortly. Will run it by you then. Thanks!


Mark-

Would it be too much to add a washer into this?


Also, here is a very rough layout of the bath room as we'd like it.

Just a couple of things to point out.

1) The black dot in the upper right hand corner is the 3" stack.

2) On both floors, the wall on the right and the wall on the bottom are original 8" thick solid brick walls. On the main level, we will be framing the wall out with 2x4 and covering in drywall. On the 2nd level, we will be leaving the brick exposed.

3) The floor joists will be 2x12 and will run from left to right (the long way). The floor for the 2nd level will actually be sistered 2x12 because we will be installing an antique clawfoot tub.

4) The left wall and the upper wall are both exterior walls. I haven't decided if I will frame them using 2x4 or 2x6.

So, that said, what do you think? Is this a reasonable layout? It seems intuitive to me. How about from a plumbing perspective?

With the joists running from left to right, I think the only drain that will need to run through a joist is the 2" tub drain, right?

What are the rules for notching or boring studs in a load bearing wall? Is it no more than 40%?

I've spoken with a local plumber who confirmed that wet venting is allowed, but I have a call into the inspector's office.

Thanks!

Hi..

If you want to add a washing machine is there any chance you can connect the 3" from the new bathrooms into a 4" pipe instead of the 3" from the existing bathroom? Let me know.

DO not NOTCH studs...drill them. The 1/3 rule applies to joists not studs. With studs you want to keep the hole as small as possible is all you can do.

The layout seems fine... pretty much lays out as I posted at the first picture with WET VENTING... just slightly different.

I'll try to draw up a plan for you in the next day or so... won't take too long.

Answer my question.

Chat soon.

MARK

I do not believe I have a 4" pipe anywhere, at least not above ground, unless I am misreading things. I will post a photo tonight, in case you can see something I am missing. Basically, there is a 3" cast iron that comes up out of the concrete slab and goes straight up to the bathroom. I believe it is 3" top to bottom, but could be wrong.

On the studs, I'll be sure to drill, not notch. My concern is the 2nd floor lav where the 1.5" drain line will have to run through a couple of exterior, load bearing studs. Due to space issues I am thinking of framing out in 2x4, but can I drill a hole for a 1.5" pipe through a 2x4? Also, I will need to drill through the top and bottoms of the studs to bring up the various vents. (I will run the 3" stack in a chase on the corner so I won't have to run it in the wall.

You can drill a 2.25" hole for 1.5" PVC pipe...works fine in a 2"x4" stud (i.e., 1.75" x 3.75").

As you noted, you can bring the stack up in the corner or you could build the wall using 2" x 6" studs....you decide.

I'll wait for the picture...There has to be someplace where there is 4" in the house? Where is the main cleanout? Let me know.

Hmm. Now you have me thinking a bit more about the current setup.

There's actually only 1 cleanout in the whole house that I am aware of. The 3" stack that services the upstairs bathroom passes through a large cleanout about 3' or so before it enters the concrete slab. Perhaps the pipe after the cleanout is 4"?

See if you can post a picture... see what we think here. I have almost never seen a home with only 3"... hmmm?

Let me know.

I will try and get a picture tonight.

For what it's worth, it's an older home, circa 1930 (but you're up in Boston where homes are even older). I know there's only 2 stacks, a 2" and what looks to be a 3", but I could be wrong.

Can I measure it? If so, how?

Yeah... I've been all over new england states and have only seen 3" in a few cottages...so interesting if you only have 3".

Most hubs of cast iron pipe/fittings have a number and an SV (service weight) or an XH (extra heavy) cast into them (raised above surface)... see if you can find the number and which letters are present.

This would be on the hub (the cleanout?) itself? In indeed this is a 3" pipe into a 4" pipe, there should be two numbers on the hub?

I will check on that tonight, for sure.

Also, what do SV and XH stand for?

Reread my last post regarding SV and XH... ok?

The hub is the enlarged bulbous end on a pipe or on a fitting... see picture.

Great, will do!

Sorry... I posted an updated picture while you were writing.

Ok, so I am pretty sure it is 3" all the way through. I can post a picture if you want, but there is a number 3 on both hubs. I didn't see any other text, although the pipe that runs down through the slab is embossed with the words "permanent pipe."

Now, not sure if this matters, but it is unlikely all of this will ever be going at the same time. Also, we have a new high efficiency washer.

Any thoughts?

The newer high efficiency washing machine is actually what I was concerned about.. LOL

Here I would have to refer you to that local inspector you said you would talk to regarding wet venting (although plumber friend said was OK).

I think you are pushing the limits. In my area you can have a great number of fixture units on a 3" drain line, but 3 toilets is maximum (in some areas TWO is maximum)... and now the high efficiency washer plus all the fixtures... hmmmm?

Always best to check with local authority.

I'll draw the plan up tomorrow sometime... based on wet venting... :)

Let me know the details as you get them.

.

Mark-

Thanks so much.

Out of curiosity, why is the high efficiency washer worse? I thought it uses less water?

Let's not worry about the washer. It would have been easier to tie it into this, but there is another option all together. No worries. Let's just stick with the additional 1.5 baths?

Still waiting on a call back from the inspector... they're not particularly helpful/friendly/responsive here. But I feel confident on the wet venting thing, the plumber I spoke to is licensed and does plenty of work here.

The high efficiency washer uses less water but the new pumps pump at a greater volume and pressure than the older pumps did.

Check with that inspector to see MAXIMUM number of toilets on a 3" drain line in your area... we can take it after that... ;)

Thanks...

MARK

Mark-

I finally heard from the inspector right before I left.

He confirmed that wet venting is allowed.

He referred me to the IPC and indicated the following regarding fixture units:

WC=3
Lav=1
Tub=2
Washer=2

So, I have 3 WC(9), 3 Lav(3), 2 Tub(4) and possibly 1 washer(2), so at most I have 18 fixture units.

He added the that I can have the following:

Horizontal Branch= 20 units

Total per Branch Interval=20 Units
Total for Stack of 3 Branch Intervals or less=48 Units
Total for Stack of More than 3 Branch Intervals=72 Units

He also indicated that with a 1/4" slope we can have up to 42 units on the main drain

So, he said, without of course reviewing any specific plans, that I should be fine, even with the washer.

Am I totally missing something here?

Thanks!

Nope... just wanted to be absolutely sure.. ;)

Let me know where you are planning for the washing machine... add it into the drawing and I'll draw up a final print... ;) I won't be on until later tonight.. ;)

MARK

Thanks so much. I am glad everything seems in order.

The washer is more of an add on here and is actually not a part of the addition. There is a closet on the main level of the home (where the powder room will be added) where we would like to place the washer. It is located such that the drain from the washer would tie into the new 3" horizontal run after it enters the existing house from the addition. My thoughts on the vent would be to run it under the 2nd level floor and tie it into the powder room vent. Can this work?

Mark-

Just checking in on this. Not sure I can add the washer to the diagram as it is on the other side of the home. Maybe I can explain it though. It is on the same level as the powder room. The drain would be a straight shot to the horizontal 3" running from the addition to the main drain, somewhere between the 2nd and 3rd long sweep.

Thanks again for everything!

OK... I'll work it in where you mentioned. I'll draw this all up over the next day or so, but will definitely post all by Saturday sometime...

Talk then...

Mark-

Just seeing this now. Thanks, I can't appreciate your help more!

Can't wait to see what you come up with.

Many thanks and best!

Bump?

I got the BUMP... ;) I'll work on this tonight. I should have it posted by early AM.

You're great. Thanks!

Sometimes... just need the extra reminder is all... :)

Thanks.

Hi Stubits:

To begin with... when you lay out the joists for the new addition make sure that the first joist in from the outer wall does NOT end up anywhere near 12-15" to center from the finish wall....if it does you will end up having to cut or head the joist off...so be aware of toilet rough when laying out the joists upstairs and downstairs..ok?

Next, if you install the tub as you drew it with the shower valve on the end opposite the outside wall then you will need to add an 1.5" vent for the tub... it will be too far away to utilize the wet vent from the sink. I drew the 3rd floor bath with the tub being wet vented (in other words I turned the tub toward the outside wall as I figured the pipes would be exposed since this is a clawfoot tub... right?). If you decide to keep it the way you presented it then yoou will need to add the individual vent and connect that back into the vent pipe from the sink or washing machine.

I did not include al the 90s you mentioned... you can place them as needed. I did include the washing machine with a rough idea of how to install it.

Most important with the washing machine is that you pipe it 2" with a 2" ptrap and the standpipe coming out of the trap should be about 30" tall (keep fittings close to floor for this to work out well.

The toilet closet flange roughs in at 12" from the rough stud wall.

The sink drain should be between 18" (for vanity) and 20" (for pedastal) off the finish floor.

The tub drain will need to be determined by where you intend to place your clawfoot tub. The waste line usually transitions over to the tub waste and overflow assembly below the floor but with a desanco fitting about 1/2" above the finish floor. We can discuss this more later.

I have included two drawings. One is a side view diagram. The other is a top down view (waste pipes only)... hopefully, combined these will make sense.

Check out the drawings and let me know if you have any questions...

MARK

Wow, this is great!

Couple of really immediate questions, I am sure mostly because I am not accustomed to reading these diagrams.

First, in general, is the main 3" stack located in upper right hand corner?

Second, on the full bath, is the toilet located on the same wall as the lav?

Never mind! Looking at the second set of drawings, it is totally clear.

OK, so some real questions...

What do you mean when to roll the wye above the center of the drain?

Also, how accessible do the cleanouts have to be?

Finally, I read, somewhere, I don't know where, that if you have multiple 90's, but they are less than 40' apart you only need one cleanout? Yes, no?

On the 1/2 bath, you want to roll the 3"x2" wye above the center of the drain line for the vent to be a legal vent.

On the full bath you want to roll the 3" x2" wye above the centerline for the same reason as above, but the 2" wye for the tub can come off the 2" drain line it shares with the sink just slightly cocked above center.

Cleanouts need to have 18" minimum clearance and need to be accessible. After 2 90s I would install another cleanout. Easy/cheap to install now... sucks later... ;) Just in case the inspector insists on extra ones... you know?

Keep 'em comin'...

Post more questions when they come up... I'm off for now. I'll be back on later tonight!

First, what does 18" of clearance mean? The cleanouts can be installed behind an access panel, right?

What type of fitting is used to connect the vents on the vertical?



Also, curious about implementation.

So, the floor joists will actually run just the way you drew them in your diagram (great job!), they will be 2x12, and in fact in the 3rd floor I will sister them just to ensure they hold the weight of the tub.

First, the plan is to run them 16" on center, as such the first floor joist in should be about 15.25" off from the wall, will that work? If not, how is this usually handled?

Given the size of the joists, I should have no problems running the 2" tub drain, right?

How about running the 2" vent pipes in a 2x6 exterior/load bearing wall? How about a 2x4 exterior/load bearing wall?

18" clearance simply means that there cannot be anything... except an access panel... in front of a 3" cleanout for at least 18"... so a plumber can snake the drain without obstruction.

To install the vents into the vertical stack you will use either a sanitary tee or a double sanitary tee fitting. This fitting needs to be turned UPSIDE DOWN so rain water can run down the stack and whatever water flows into the sanitary tee will drain back to the pipes by gravity...

Note here, that all vents pitch away from the stack toward the drain at about 1/4" pitch per foot (see picture). Drains pitch at 1/4" per foot toward the stack.

Now, the joists... I just wanted to be sure you understand that the first joist must be taken seriously as it could have consequesnces down the road. As long as you actually stick to 16" on center...you should be fine!

No problem on 2"x12" for tub drain. On a 2"x6" joist you would need to keep the drain/trap high up in the joist bay to install the trap properly. With a 2"x12" joist...run pipe as gravity allows. Ptrap depth should NOT be an issue here...;)

A 2" vent requires a 2-9/16" hole which works fine in a 2"x4" exterior load-bearing wall (3.5" wide). It is really no different than installing a 4" pipe in a 2"x6" wall. As odd as it seems.. it is permissible!

Keep throwin' them out as you think them up...

Ok, so far everything is making tremendous sense. The graphics are excellent. Just out of curiosity, what program did you use for the DWV drawings?

Ok, so two more questions...

1) This is a very simple question, but how exactly do you measure the 1/4" pitch. I am sure you must use a level, but are there any hints or tricks? Where on the level is 1/4"?

2) How do I tie into the cast iron stack? I know I need to support the stack, right? Any tricks or tips here? Then, how do I go about cutting the stack, can I use a metal blade on my reciprocating saw? Is there something better? How much do I cut out? What fitting do I use to tie in?

I use my paint program... ;) Then I save as a JPEG file so it will fit the size requirements of the site.

In terms of pitching pipes at 1/4" per foot... if you use a two foot level you can tape a 1/2" block of wood (or metal) on one end of the level and then when you place it on the pipe and it reads level you know you have 1/4" pitch per foot of pipe.

If you use a 1 foot level, tape a 1/4" piece of wood. If you use a 9 inch torpedo level you would tape a 3/16" piece of wood, etc...

In terms of supporting the cast iron stack you will want to purchase a RISER CLAMP (see pictures)... install under a HUB if possible and then use 2"x4" studs under the ears to support the hanger (see other picture).

You can use a reciprocating saw with a bimetal blade (8-10 teeth per inch) or a diamond sawzall blade by Lennox (if you can find it at a local plumbing supply store). You could also rent a snap cutter... but I don't recommend it for this case as it can also crush pipes and cause even more work for you. Stick with the sawzall.

Whn you plan for the cut, measure the fitting and add 3/4" to total length to be cut from the stack... this will help to accommodate the RIBS in between the clamps and allow a little play for a slightly crooked cut.

Finally, use shielded clamps (cast iron x cast iron) and 3" NO-HUB cast iron sanitary tee fittings... do not install PVC into the stack... OK? The NO-HUB cast iron fittings are available at all plumbing supply stores. Then transition to plastic using a 3" cast iron to 3" plastic shielded clamp... ;)

Let me know if need more...

MARK