Bathroom remodel DWV questions

[skt]

We are trying to replace a 48" tub with a full size (5") tub in a 1970 mobile home. To accomplish this we also have to move the toilet over 8" from it's current location. I have removed the wall hung cabinet above the current toilet location, as well as the towel cabinet which was 12" wide and floor to ceiling. I cannot move the furnace. There is one lav, a tub/shower combo, and water closet. There are two vents, one serves the lav and the tub/shower combo, the other serves the water closet and I think the kitchen sink, which makes me queasy, to say the least. Obviously someone has had their way with this plumbing, because there is NO WAY any inspector would have approved this as currently routed. There is a washing machine waste line that is 25' long, that is the last drain to empty into the soil line, and it has no vent whatsoever. The washing machine drain will be removed completely from the line for the time being, so for now it is out of the equation. The lav and tub/shower are vented as follows: the lav has a dry vent to the roof, and the tub/shower is tied into that waste line and the vent is tied into that vent above the lav. The waste line for those two units runs horizontally through the floor and ties into the soil stack at the same place as the kitchen sink and the toilet and is a mess. See the attached picture.
What I want to know is this: I have attached a drawing of what I propose to do. The tub/shower and lav will remain vented together and joined to the same waste line as they are currently. After moving the toilet I will vent it to the 2" vent that currently runs through the wall and up through the roof. Above that connection I will tie in the tub/shower and lav drain, and above that connection I will tie in the kitchen sink drain with it's vent tied in to the 2" vent above everything else. The red portion of the drawing is what I am most unsure of. I have no way to reroute the vents through the roof, and I am not a plumber, obviously. Any advice would be greatly appreciated. I have approximately 24" from the bottom of the closet flange to the gravel under the trailer to make these connections, and approximately 6' horizontally, then the soil line turns downward and I have no room to work with.
(I stole this drawing from somewhere else on this forum and reworked it to suit what I needed, so to whoever owns this work, I am sorry and also grateful for the beginning.)

If you're looking at the drawing, the drain from the kitchen sink is actually behind the toilet, but if I were to show it that way all you would see is a straight line, so imagine it is turned 45° clockwise.
The tub/shower and lav connection would be turned 45° counterclockwise.

 

[hj]

You admit you are not a plumber, therefore there is no way you could tell WHAT an inspector would have approved, especially since mobile homes have their own codes. Trying to follow your convoluted description of what you want to do is very confusing and both of your drawings appear to be the same.

 

[Sponsor]

 

[Terry]

24" is a lot of space to work with.
Like hj, I'm getting confused on this. Really confused that you are deleting the washer plumbing too.
I would look at adding a vent for that and keeping it.

 

[skt]

24" is a lot of space to work with.
Like hj, I'm getting confused on this. Really confused that you are deleting the washer plumbing too.
I would look at adding a vent for that and keeping it.

Apparently I posted the same pictures 2 times, it wasn't intentional and I apologize for the confusion.
The reason for deleting the washer plumbing is this: currently it is a 28' 6" piece of 1" PVC with a trap that is 30" below the floor, it has no vent, the pipe has to go uphill for 51" before it can go downhill where it empties into the soil pipe before anything else, so whenever the toilet is flushed, or the sink is drained, it gurgles and belches out fumes. It is in a stick built addition to the mobile that is used as a family room and that puts it on a lower level than the rest of the plumbing by at least 40". It's standpipe is 36" above the floor and it has been known to spew liquid when the washer is draining and when the rest of the system is being worked hard (as in grandkids in and out of the bathroom constantly on weekends). Right now I have the standpipe capped so that I can use that room without gagging every time I draw a breath of air. At this point laundry is the least of my worries.
We HAVE to get our plumbing in usable order by November 21st. If I could afford a plumber, I would hire one, believe me. When we started this project we had no intentions of turning it into a major remodel. Once he saw the extent of what he was up against he decided that if it was going to take that much work to make it right that he might as well have a full sized bathtub when he was done.
To start with, he just went to look under the trailer to see what was causing the problems with the odors, and with the washing machine. This is where the nightmare began.
Under the trailer there were roughly two tons of raw sewage in the crawl space. There was NO connection to the septic at all, except for that 1" PVC pipe from the washer. Someone had had a plumbing problem previously, and rather than repair it, or call someone who could, they had taken 3" plastic dryer vent (the kind that has coiled wire in it to make it stretchy) and hooked it onto the soil pipe that you see in the photo above with a hose clamp. Actually 6 hose clamps all put together to make it long enough to go around the pipe on the toilet end, and then just shoved the end of it into the sewer pipe. Needless to say, it didn't stay there, it was just running raw sewage into the crawl space. So our first order of business was to remove that waste and spread 200# of lime and antibacterial agents in the crawl space. Then we had to leave it open to the air, and have the soil tested 3 times till we got the all clear to proceed. In the meantime we are using a Port-A-Potty in the yard. The next order of business was to spread more lime, put down a plastic barrier and then 1 1/4 tons of gravel in the crawl space. That brings us up to date.The carpentry work inside the trailer is not a problem, neither will be moving the lav over 6", as well as moving the toilet 6" too. I even have a handle on moving the water supply for the new tub, and securing the valve and stops in the new framing. The problem lies in making sure that we have the vents hooked up properly and that they are all going into the waste in the proper order. I do know how to make sure they are at the proper grade and how to use the hangers and how often to make sure that they stay where they are supposed to, etc. There is a cleanout where the 3" soil pipe joins the septic line, approximately where the line ends in my drawing. If we can just get this done, we can deal with the laundry issue at another point in time. Any help would be greatly appreciated.
In response to hj, obviously I do NOT know what the inspector would approve or I wouldn't be here asking for help from those of you that do know, but I stand by what I said above - there is no inspector anywhere that would have approved the plumbing in THIS place. I'd stake my life on it.

 

[Tom Sawyer]

It's a trailer, do whatever you want. It was never properly vented in the 1st place.

 

[skt]

It's a trailer, do whatever you want. It was never properly vented in the 1st place.

Just because it was done poorly before is no reason to perpetuate the problem, but thanks for your advice.

 

[Tom Sawyer]

You'd have to tear the entire underbelly out if you want to do it right. The wall partitions aren't deep enough to get anything bigger than 1-1/2" pipe into and most trailers use cheap AAV's rather than vent through the roof and the few vents through the roof they have are undersized and not code legal but again, it's a trailer so who cares? Don't put a lot of money into something that just continues to deteriorate year after year. Oh and your existing tub most likely has the trap above the floor. They do that for two reasons. One is that below the floor they tend to freeze and the other is because that big hole you need to cut in the sub floor is a great place for vermin and rodents to get in.

 

[skt]

You'd have to tear the entire underbelly out if you want to do it right. The wall partitions aren't deep enough to get anything bigger than 1-1/2" pipe into and most trailers use cheap AAV's rather than vent through the roof and the few vents through the roof they have are undersized and not code legal but again, it's a trailer so who cares? Don't put a lot of money into something that just continues to deteriorate year after year. Oh and your existing tub most likely has the trap above the floor. They do that for two reasons. One is that below the floor they tend to freeze and the other is because that big hole you need to cut in the sub floor is a great place for vermin and rodents to get in.

If you had read what I wrote, there are 2 vents through the roof now, one is 1½" and the other is 2". My walls are 2" x 4", even the interior walls. The existing tub trap is not above the floor, I know because I put it in. Once the plumbing is corrected, there will be another sub floor belly put in to stop the piping from freezing and keep the vermin out. And for your information, the two vent pipes that are through my roof and snow roof, do meet the code for this area. Again, thanks for your very helpful and insightful advice.

 

[skt]

24" is a lot of space to work with.
Like hj, I'm getting confused on this. Really confused that you are deleting the washer plumbing too.
I would look at adding a vent for that and keeping it.

What I need, more than anything else, is this: what fittings to use to make the connections properly, and where to locate the cleanouts. Anybody that can answer those questions would be much appreciated. Thank you in advance.

 

[Terry]

The drawing looks pretty good.
I see the wye below the toilet for the kitchen, which then vents with 2".
The lav and shower are vented with 1.5"
The fittings for the lav and shower would have combo's or wye fittings on their back for the vents.
The kitchen would have a santee on the vertical for it's vent.
The lav and shower can cut in below the kitchen sink below the kitchen like you have it drawn with a Santee, or it could also cut in on the 3" below the toilet.

The shower is a 2" p-trap, though fifty years ago there were run using 1.5"
The cleanout would be in the kitchen cabinet for the sink, 2"
The end of the line cleanout for the toilet before it enters the ground, a 3"
Normally a cleanout on the lav would be close enough for the shower if it's within five feet.

 

[skt]

The drawing looks pretty good.
I see the wye below the toilet for the kitchen, which then vents with 2".
The lav and shower are vented with 1.5"
The fittings for the lav and shower would have combo's or wye fittings on their back for the vents.
The kitchen would have a santee on the vertical for it's vent.
The lav and shower can cut in below the kitchen sink below the kitchen like you have it drawn with a Santee, or it could also cut in on the 3" below the toilet.

The shower is a 2" p-trap, though fifty years ago there were run using 1.5"
The cleanout would be in the kitchen cabinet for the sink, 2"
The end of the line cleanout for the toilet before it enters the ground, a 3"
Normally a cleanout on the lav would be close enough for the shower if it's within five feet.

Thanks very much for the super fast response!. Without sounding any dumber than I feel right now, by combo do you mean a combination Y-1/8 bend? And the santee on the kitchen would be with the angled portion going into the 3" pipe to direct the flow downward and the vent attaching to the top of the tee?

 

[Terry]

A combo is a wye and 1/8" bend.