Need Thoughts on Shower Drain on Slab Foundation

[Redrum]

Hi;

A bit of a background to my quandry. I have a seasonal camp/cabin in Northern New York that is built on a concrete slab foundation in the 50's, and worked on by several different hacks over the course of it's life (the stories I could tell you of what I found...)

As far as plumbing there is only a toilet, shower, kitchen and bath sink. The drains were always a bit slow at times, and on investigation (digging), I found that only the toilet feeds to the septic tank. There were two black ABS pipes (kitchen and bath sinks) which I found, but I could not find the shower. Peering down the shower drain, I got the impression it went deeper before it tied to the other ABS lines. I verified all lines tied together* by running water into one, and having it back out the others (because destination is clogged/slow).

*They tie together somewhere...there must be a drywell of sorts somewhere, but I have no idea where and how to find it.

So, with the help of the local plumber (see picture) we ran the kitchen and bath sinks to the septic tank, and left a stub out in the location where the shower drain would be, for me to address in the future.

Now it's time to do something about the shower, and I am a looking for thoughts on the best way. Please note that the place has been gutted to the studs, walls moved, rewired, etc, so please feel free to suggest anything (i.e. running a pipe in a wall - no problem).

My two thoughts, along with their associated uncertainties:

1) Remove the shower stall, cut the concrete, run a 2" drain, p-trap in the floor, vent up the outside wall, tie into the stub. My concern is not breaking up the 4" or so of concrete in the floor, it's what will I encounter when I try to go through the rim of the slab, where it is thicker, rebar? will I hurt the integrity of the slab?

2) Other option - over the floor rough shower stall, come out the side of the wall low, sweep elbows down into the stub. My question with this approach is where is the P-trap located? Are there special p-traps to fit below those stalls, or, would I have the p-trap outside, and if this is the case, how to vent?

Further complication, and there always is one it seems, is I need to address the existing vent that goes under the eaves. I vaulted the ceiling inside the camp, and will now need to vent the ridge and the eaves, requiring that vent to go through the roof. One thought on a hack would be to bring the vent back inside (with 45 elbows) and tie it into new shower vents, then through the roof. I know the right way would be to redo the toilet plumbing too, but I would love to avoid that.

Any thoughts to break my mental stalemate?

Jim

 

[Redrum]

ok, maybe my post is too long. let me boil it down to two questions:

1) Should I be scared of cutting out the concrete slab from about 24" in, through the side of the thicker part of the slab? I don't think I can go below the thicker part as the entry to the septic is rather high.
2) With an over the floor rough shower, where does the 2" p-trap go? Is there a special p-trap that will fit in the limited space? Is the P-trap after the drain exits the shower pan area? If so, can a p-trap be outside?

Thanks for your help...
Jim

 

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[Jadnashua]

You can rent a gasoline powered concrete coring drill which would allow you to get through the outer foundation without cracking it all up.

You don't really want to have your trap a long ways from the drain as the pipe on that horizontal section will still need to be sloped, and will accumulate hair, dead skin, soap scum, body oils, and residue from soaps and shampoos...that will tend to smell eventually. Going vertical into the p-trap scours that part pretty well, and the water in the trap blocks anything below it from being an olfactory assault.

With a 2" drain, you have a maximum of 5' on the trap arm before it must be vented and can then turn down.

Vents can have twists and turns in them as long as they still have proper slope and rise so that condensation and precipitation can flow through them without becoming stagnant. If you use this in the winter, vents outside tend to need to be larger in diameter to prevent hoar frost from sealing them closed. There will be a lot of hot/moist air moving through, and once outside, that really cold air can freeze things fairly quickly.

The old sinks and shower might have gone to a drywell verses the septic system, but that probably is no longer allowed. Over time, those can tend to stop working well as the soap, lint, hair, etc. fills in the pores of the dirt lining the drywell, stopping or slowing how fast the water can be absorbed into the ground. Do you have an area that seems to get damp after you've been at the cabin for awhile outside? AN area where the grass or shrubs or trees seem to do better than others? If so, you may have found the location of the drywell, not to be confused with potentially similar reactions near the septic leach field(s).

FOr actually building a new shower, suggest you check out www.johnbridge.com when it comes time for that. That may point you towards the use of a particular type of drain for your shower that you'd need to know before you close up the slab to have everything in the right position for what you want.

 

[Redrum]

Thank you for your comments. I didn't know about a coring drill. A hole saw of sorts? I assume I would break out from the inside, then get to where it thickens and drill into the broken out area from the outside. Maybe a 3" or bigger hole to fit the 2" pipe through....

Understand on the venting, and thank you for the good reasoning on why to take a shower drain directly into a p-trap.

I still don't understand how they fit a p-trap in a "above the floor rough" shower stall.

As far as the dry well, I gave up before I even started trying to find it. The cabin is in the Adirondack park, in a pine forest of sorts, on a hill, leading to a lake with sand soil. No grass (no mowing!), all trees and ground cover, and a deep bed of pine needles. The perk is excellent. I am sure it is no longer allowed, and the reason it failed is for the reasons you mentioned. So, I directed the basins to the septic, and now want to do the same with the shower.

Thanks again
Jim

 

[Jadnashua]

Unless you bury the p-trap below the floor, you end up needing a false floor, raising the height and thickness of the shower pan making it a potentially huge step up to get in, but probably more dangerous and inconvenient, is that step down out of it when your feet and hands are then wet! Was in a small, quite old hotel in London one time that had a shower built that way...almost killed myself stepping out of the shower! Not fun, not recommended (but possible). My sister has a bathroom in her basement and the sewer outlet is above the floor. To keep the plumbing so it didn't need an ejector pump, they raised the floor of the entire bathroom, which also lowered the ceiling in there. IT works, but it's still a bit awkward but at least you're less likely to be doing this while dripping wet coming out of the shower since it's a 'normal' height and step into the rest of the room. You still need a step up into the whole bathroom, though, rather than it being on the same level as the rest of the place.

Spent some quality time in the Adirondacks at summer camp, and hiking the mountains...climbed Mt Marcy 3-4 times. Like the area, hate the black flies! Very pretty. My hiking days are pretty much over, but I still like the scenery. Went winter camping once with about 4' of fresh snow...large group with snowshoes...the first person had a tough time...the last, was like walking on a sidewalk! Below zero in our shirtsleeves until we stopped to keep from getting soaked in sweat. Deep enough so there was no wind...a surreal experience in the moonlight as we got there after dark with a crystal clear sky and no town/city lights to detract from the brilliance and visibility of the stars.

 

[Redrum]

Hi jim,

Nice description of the adk. I to have been to Marcy and a few of the other peaks. Never did the winter thing. Luckily our community does bti treatment of local moving waters, which minimizes black flies, but they still get ya until July. I have several itchy bumps as I write this. We are lucky to be on a lake where motorized boats are prohibited, just canoes and kayaks. It can be unbelievably quiet and pitch black.

Regarding the above the floor rough, I was referring to something like this that my local kitchen and bath guy can get:

http://www.clarionbathware.com/re5636x.html

The x designates over the floor rough, and it has a 8 inch threshold that drops to a 3 1/2 floor (see PDF drawing). The question is getting the ptrap in the 3 1/2 inches. The threshold actually wouldn't be bad. Since the camp is built on a concrete slab (all of the floors are currently painted concrete...for now. The place is rough but getting better) I plan on finishing it like I did a 4 season room at home - concrete, then vapor barrier, then 1+ inch foam, 3/4 advantech subfloor, vinyl plank. So, the whole floor will come up 2 inches, so the threshold becomes, 6ish, and the shower floor about 2 inches above finished floor.

Perhaps I could rough the horizontal pipe within the 3 1/2" but break out a bit of the floor for the bottom of the p trap, then fill back in with concrete around the bottom of the trap. But it seems that "above the floor" should mean just that.

My initial inquiry was that perhaps someone has used one of these guys...

I'll try to call the manufacturer tomorrow. Thanks again.

Jim

 

[Jadnashua]

That will work, but having the floor a step higher is still a bit dangerous in my experience. While stepping over the curb can be annoying if it is tall, stepping down out of a wet/slippery surface is messy, especially if it's not something you use every day and learn some muscle memory. The first time you forget and do a face plant, you'll understand what I mean. Especially risky if you have occasional guests.

 

[Redrum]

I guess going into the slab is inevitable. I don't mind tasks that I have never done, except the ones where you get half way through and have a bigger mess on your hands than when you started. I try to think everything through ("what if" the possible issues) before I start, but it's hard to know what to expect with a slab built in the 50's. Maybe I'll see if the local plumber feels like doing it . Thanks for your tip on the core drill.

Jim