Tub Drain: Solvent Weld vs. Slip Joint

Discussion in 'Shower & bathtub Forum & Blog' started by bronsonb, May 1, 2012.

  1. bronsonb

    bronsonb New Member

    Messages:
    19
    Location:
    Smyrna, GA
    Hi All-
    We're in the midst of updating our bathroom and replacing all fixtures. We have a new jetted tub on the way to replace the old cast iron behemoth that is currently sitting in pieces next to my garage awaiting a trip to the recycling center. New tub is the same size as the old tub (although I know the drains will not likely match up and have already started replacing the Ptrap).

    I am weighing the pros and cons of using solvent a welded tub drain versus a slip joint model. The tub I am getting is a Jacuzzi Primo from the blue box. It is skirted but has an access panel across the front allowing access to the tub's motor and also to the front where the drain is located. Until I get the tub to the house, I won't know how much access I have though.

    My concern with a slip joint drain is that if I don't get the joints lined up and tight I might get a slow leak that I don't discover for several weeks or months until it's stained the family room ceiling below. Also, it seems that a solvent welded drain would hold together better, but am I wrong?

    If I go the solvent weld route, I am curious as how to best get everything together with access from the side and maybe access behind if I cut a hole in the closet that backs up to the tub. However, there's a vent line and a cold water line partly in the way from that vantage point behind the drain.

    I'm going to be replacing the Ptrap in the joist bay below, so I can get the new Ptrap to line up perfectly with the drain from the tub, so that shouldn't be a problem. But there's still the question of how to hook up all of those pieces so that nothing leaks and everything flows and drains properly.

    It seems the advantage of the slip joint is that it's more forgiving and I can take multiple tries. I read the tip about coating the threads with plumber's putty before assembling to help them seal (did I get that right?).

    With the solvent weld, there's only one shot after repeated measuring to get it right before you have to but a new set of pipe, but it seems like it would be more stable.

    What would you do? I guess there's option #3 --> help the local economy and pay my plumber to hook it up. I take it that this is a fairly straightforward job for a pro who has likely done this dozens of times and can do it in his (or her) sleep?

    Thanks, in advance, for the advice.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,009
    Location:
    New England
    You likely don't want anything on the threads with a slip joint. Now, on a sink tailpiece, that can be a different story - the gaskets used and how they seal are different.

    Since you have access, my take is to use the cemented connection. When setting the tub, make sure it is level and properly supported. If the subfloor isn't perfectly flat and level, and the tub rocks or warps, it can create long-term problems. Whether it requires shims or bedding in mortar would depend on the tub and the floor. If you're lucky, it has a full support and your floor is flat and level.
  3. bronsonb

    bronsonb New Member

    Messages:
    19
    Location:
    Smyrna, GA
    Thanks Jim! I am actually pouring SLC for the entire bath floor. I had one joist that was crowned, and I was able to plane it down, but then another joist was a tad low. The floor is not bad, but it is not 100% level. I'm investing in a few bags of SLC to make it level. I don't want to have issues with the tub.

    According to the Jacuzzi Primo tub directions, it doesn't require a setting bed as it supposedly fully supported, but they recommend it. And they actually recommend plaster over mortar.
    Strange.

    Thanks for the advice on the solvent weld. That is the route I am going to go. It just seems like it'd be the more stable solution in the end.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,636
    Location:
    Cave Creek, Arizona
    I, and many other plumbers, would assemble the drain to the tub BEFORE moving it into place. Then after making the necessary measurements, connect it to the "P" trap, finally place the tub into position over the drain assembly. If it is done correctly and everything lines up, then you insert the drain plug and screw the overflow plate on.
  5. bronsonb

    bronsonb New Member

    Messages:
    19
    Location:
    Smyrna, GA
    That's actually the way I was thinking about doing it. I figured I'll have to measure a few times to make sure I have it all in the right place. I do like the idea of installing the drain and getting all the solvent welds done BEFORE setting the tub as it will be SO much easier to work without the tub there.

    Thanks for the tip!
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,009
    Location:
    New England
    If you've never used SLC before, read and heed the instructions carefully. Over a wooden subfloor, most want lath installed along with a thicker layer (most want a minimum of 1/2" over the highest point). Plus, all SLC requires the proper application of the primer. There are a few SLCs that can be used thinner over a wooden subfloor (and most can be feathered over a slab), but they are not the majority. Make sure to use something like sill seal foam around the perimeter - you do need an expansion joint at the walls. Plus, it WILL flow through any holes or cracks, so those need to be addressed before pouring. For a DIY'er, do NOT get the rapid set...the 'normal' stuf is plenty fast! Mixing properly requires using a timer, accurately measured water, and a drill that can provide the torque necessary at the designated speed. It can quickly overheat a wimpy drill! The basic key is to mix and pour quickly, move the material to wet all surfaces, then leave it alone. If you try to work it much, it will start to set and you'll have waves and a really big expensive mess. It's not like doing a cement slab - you CANNOT work it once it starts to set. It flashes from liquid to set in a very short period of time. Hotter days, it sets faster. Using cold water gives you maybe another minute or two. Don't use warm or hot! Avoid room temp water if you can. Measure carefully.

    If the tub sets flat and level once set, you don't need to bed it in anything if it has a factory full support base. Plaster would work, but it can set up pretty quickly, so you need to be fast. It does 'smush' easier than say deck mud.
  7. bronsonb

    bronsonb New Member

    Messages:
    19
    Location:
    Smyrna, GA
    Thanks again for the tips Jim. This will actually be the third time I've used SLC. I remember being completely terrified of it the first time I used it. I tried to get the "ES" (extended set) version, but no one stocked it and all of the suppliers kept talking me out of it. So I recruited a neighbor to help me with the mixing and pouring. I had to do 7 bags, and I recall you have about 10 minutes to work with it before it sets up. I was embedding the heat mat in our master bath. It all worked WONDERFULLY in the end, and I had a flat and level floor to boot.

    I've got my lathe and primer all ready to go, and I thankfully have a large roll of sill sealer somewhere around the house from last year. After I finished our master bath, I redid my parent's strange 1.5 hall bath (a very odd jack and jill type set up where the tub actually separated the two baths...you stepped through the tub from one half of the bath to the other). I had to use SLC there due to one joist being higher than the others. I remember on that pour the SLC found a hole I missed and started pouring into the crawlspace. I heard it pouring but couldn't see where for a minute. When I found it, I tossed a handful of dry SLC into the spot, and that firmed it up. But you are so right about how it will find those holes.

    I've actually got the buckets I used for my SLC last year still in my garage, and I had marked the fill line on them. I was very impressed with how well the SLC worked. Mixed it two minutes, and it was perfect as pancake batter. Primed everything just as the directions say. Had lathe installed. All went well.

    I do appreciate the tip regarding not needing a bedding compound if the floor is level. I think I'll leave that out assuming my SLC pour goes well. I am afraid that if I use something, it will cause even a modest offset from whatever I measure regarding drain placement. We'll see how it all goes.

    I'll try to post some photos of before / during / after.

    Again, I really appreciate your help Jim! I can see how you got to 16,000 posts in just a few years!
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