Bathtub Plumbing

Mike Goetzke

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Jul 12, 2008
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I'm working on a bathroom remodel. Will be replacing the original blue cast tub with probably a steel white one. We have a tri-level and this bath is on the top floor so was worried about drain access. I was hopeful a hole in the lower level hall closet would allow access to the drain. After poking around with a screwdriver and using a stud finder I had to bore out a hole saw hole lower than I thought I wanted but it might be in a good spot. I can reach in with my right arm to the bottom of the tub and almost to the overfill.

My house is copper (this seems like maybe 1-1/2" od 2") so seems like this is doable by a capable homeowner?

Hopefully the new tub will have a similar drain position. Any previous experience welcome.
 
Measure the drain layout on the existing tub, check the layout on the replacement. Hopefully they will be the same, if not you may be able to find one you like that is the same.

Yes. it should be 1-1/2” drain. Being copper, you may be able to just remove the drain hub that screws into the drain shoe. This will allow you to remove the tub and evaluate the situation. You will have to remove the wall surface above the tub to remove it.

Being a cast iron tub you’ll need to bust it up to get the tub out of the house unless you can find a few strong helpers. If you have to go the bust it out route get some furniture pads from HF and cover the tub, This helps capture flying pieces, even doing this I had one job where a piece of the tub went through a wall and ended up in the hallway. There is the option of cutting it up with a recip saw, this is kinda slow. Do not use a grinder, no telling where the sparks are going, presents a fire hazard. No matter which route you choose, gloves and great eye protection is a must, the porcelain shatters and flys everywhere (bare feet are a no no also).

What wall is on the drain side of the tub? If it is a closet, you can remove the drywall on the lower section and work through the opening. When you’re done cover the opening with plywood for future access.

Pictures would help.

Only you can answer the can you do it question. If you’re apprehensive, you may be able to find a plumber who will remove the old tub and set the new one. The more prepared the space is the less time it will take them to complete the process.

Tom
 
@tjbnwi Thanks for the reply. Here are a couple of photos.

I used a hole saw to cut a visual access point but it may be all I need. The floor joists run in/out of this view but there is a wood 2x10 on the end of the joists supported by 2x4 framing that made me drill lower my original calculated location. You can sell a HVAC duct and my first thought was oh darn it but then when I looked in the hole to the left slightly I can see the p-trap and the drain runs left:

IMG_8246.jpg


It's hard to get a pic straight up - plus don't want to lose my phone but here is the plumbing. The overflow is straight up and the tub t's into this run. Like I said I can get my hand on the pipe to the tub and almost to the overflow but don't think I can cut the piping from the wall side even with a larger hole. May need to do that from the bathroom I'm guessing:

IMG_8248.jpg
 
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There should be no need to cut the pipe. Remove the drain hub from the drain shoe by unscrewing it, then remove the overflow screws. Once the hub and overflow anre unscrewed you can get the tub out.

What you describe is the most common tub drain install. The drain hub screws into the shoe/toe, the overflow “t” is the “heal” that the 3 converging lines connect to.

The advantage to copper is you can heat and de-solder it, reconfigure then re-sweat. The copper appears to be in great shape.

Making a plywood template of the new tubs drain location will allow you to get the drain shoe exactly where you need it without the tub in place. The hardest part of the reinstall will be keeping gasket/seals in place.

Tom
 
I looked at your thread where you asked about the size thread for the drain hub/plug. With the year of your home and with number of them I’ve done in your area it is a 1-1/2”-16 thread, I’ve never seen an 1-1/2”-11 in your location.

There were 1-3/8 and 1-5/8 long ago, your home is to new for one of them.

Tom
 
I looked at your thread where you asked about the size thread for the drain hub/plug. With the year of your home and with number of them I’ve done in your area it is a 1-1/2”-16 thread, I’ve never seen an 1-1/2”-11 in your location.

There were 1-3/8 and 1-5/8 long ago, your home is to new for one of them.

Tom
Thanks for all the help. I asked about the thread because my wife picked out bronzed gold Moen fixtures so need to match the tub drain and overflow.
 
@tjbnwi thanks for the help. I took a better photo of the plumbing and see there is a slip joint on the waste line but I measured the distance from the drain to the tiled wall and it’s within 1/4” of what the American Standard spec sheet shows for the tub I’ looking at - so probably don’t need to do a thing.

But, our old tub drains by pulling up and twisting a plug. Is there an advantage to c/o the piping to have a lever for the drain?

IMG_0136.jpeg
 
Maybe they're better now, but I've never seen a gold-finish plumbing thing that looked good after 5 years or more. Maybe if you have a whole-house filter and softener, but they just don't clean up as well as chromed-plating, and once the deposits are there they're really hard to remove without damaging the underlying finish, assuming the finish itself didn't get corroded.

As for drains, the lever mechanism is just something else to fail with limited access for repair. The in-drain plug at least can be replaced top-side.
 
@tjbnwi thanks for the help. I took a better photo of the plumbing and see there is a slip joint on the waste line but I measured the distance from the drain to the tiled wall and it’s within 1/4” of what the American Standard spec sheet shows for the tub I’ looking at - so probably don’t need to do a thing.

But, our old tub drains by pulling up and twisting a plug. Is there an advantage to c/o the piping to have a lever for the drain?

View attachment 376002
I would not give up the copper if it is in good shape upon inspection.

You will need to change the gland nuts and gland washers. It took a screen shot of your picture and labeled the gland nut. You may need to split the gland nut to get it off, hopefully nut. There is a rubber gland washer between the nut and the waste tee. As you tighten the gland nut it compresses the washer against the tube to seal the joint. Use metal gland nuts and rubber gland washers.

When you assemble the drain assembly, just snug the nut enough to hold every thing in place. One of the hardest things to do is set the rubber gasket between the drain shoe and tub drain hole and the overflow and tub if you have limited room to work in. The only “sealer” you will need on the drain will be a rope of plumbers putty on the drain hub/plug when you install it.

Once everything is set and aligned you can tighten the gland nuts.

If you find the toe piece tube has been cut short for your new tub it is available as a separate item.

IMG_0946.jpeg

Tom
 
I was looking at the American Standard Princeton Americast steel tub. I saw a video of one being installed and it had an integrated overflow. Don't know if I like this - makes the plumbing initiate at the bottom of the waste drain so I'm thinking further below the floor. They also seem to offer the more common two hold design. Guess I'm at the info overload point right now but thinking not time to try a new design.

Screenshot 2025-05-28 195408.png
 
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