The lesser of 2 p-trap evils

Hi, first time posting but have done a lot of reading here and appreciate the time and advice you give.

I am remodeling my bath and because of severely sloping floors am building a raised platform to provide a level surface for the tub. Would like the trap to be above the floor(unconditioned crawl space) and will have about 7" of vertical space between drain and floor, which should be enough if I don't use the tailpiece for the drain assembly and instead connect the trap to the male threads. The "business end" of the tub shares a wall with an adjoining utility closet so I have full side access to the plumbing.

Had considered using a PVC trap but have read that PVC threaded female to brass male is a no-no and against code in some places(although I'm not sure if that applies only to supplies) The other option is to use a brass trap with a tailpiece and PVC slip coupling on the outlet side of the trap but some seem to dislike brass traps because of corrosion.

Would appreciate any insight as to which you think is the better option. Thanks for the help.

I would be concerned about "severely sloping floors" before I build any platform and put a big tub full of water on it.

Raising the tub can be a trip hazard, and in some houses, if this was also a shower, could be a big problem with headroom. Some insulation may be enough to keep the trap from freezing with heat from the room (normally, there's a hole around the trap - you could box it in so it was heated by the room). You don't normally need to worry about the draining water, since it normally would flow to the drain and not freeze along the way.

I also would be concerned there wasn't a structural problem that needs to be addressed first. If that IS okay (unlikely), then removing the subfloor, sistering the joists so they are nice and level, and new subflooring would be better than a platform. Lots of labor, but not all that much if doing it yourself.

Good point but the sloping is a result of settling of piers that were put in 70 or so years ago. Joists and beams are all solid and straight. Trying to correct 70 years of settling with jacks didn't seem like a good idea. Besides, this is "old house New England" where crooked floors are a way of life.

Never suggested jacking the thing...if you take the subfloor off, attach new joists to the existing ones so the tops are level, new subflooring, and you have a nice, flat, level floor to build whatever you want on. this may also help in preventing excessive buildup. If you want to tile the floor, you can't tile to planks, you need at least a 1/2" layer of plywood on top, then either a membrane or cbu before you tile. If you take the planks off (I'm assuming that's there on an old house), you'd minimize the buildup, and provide a nice stable surface you can tile to, and set your vanity, toilet, and tub on.

You can buy a tub waste and overflow made of either ABS or PVC, that way you can solvent weld the pipes and fittings.
Don't raise the tub too much, my sister has one in Omak that is raised, and every time I step out of it I almost break my neck.
For some reason I keep forgetting how high it is. Dang!

If you are raising the tub 7", make sure you provide a "platform" on the outside of the tub that same height. There are so many ways to connect your tub drain to the trap, that we could not cover all of them, but one thing that might apply is that if your trap is going to be above the floor, that almost ensures that it will be an "S" trap, even if you are using a "P" trap to do it.

I had intended to connect the outlet of the p trap horizontally to a sanitary tee in a waste/vent stack about 12" away. This stack will connect to the main waste line underneath the floor. Does this avoid an s trap
configuration?

downeastdon said:

I had intended to connect the outlet of the p trap horizontally to a sanitary tee in a waste/vent stack about 12" away. This stack will connect to the main waste line underneath the floor. Does this avoid an s trap
configuration?

Click to expand...

That sounds proper.