Bathroom remodel copper and brass drains

[big_rat]

I've been doing some research on how to set the tub on a mortar bed. I'm going to use the sand mix that the company recommends. I will have 2x3 or 2x4s on 3 sides of the tub as stringers. I have a few questions.

1) I have a 8"x16" cutout around the drain so that I can cut the pipe, weld the ptrap and the waste drain after I set the tub down. I calculated that about 2.5" by 16" of the tub at the end will not be supported by mortar, but the vast majority of the tub will be supported (see pic, I shaded red in the tub diagram how much of the tub will be supported by mortar). I contacted the tub manufacturer and they said this is fine. I just want to ask you guys, from a practical experience is it normal to have a cutout around the drain and a little bit of the tub not supported by mortar?

2) I have read on this forum plumbers recommending to lay plastic on the plywood before mudding. I have read other recommendations to put the plastic on top of the mortar. The tub instructions do not mention plastic. Do you guys recommend plastic under, over the mortar or no plastic at all?

 

[big_rat]

bump!

 

[Sponsor]

 

[Reach4]

The advantages of plastic is that it allows separation if you ever want to take the tub out. It also slows drying which makes the result a tad stronger. Since this does not require high strength, the separation part is probably the best reason. You could even put the piles into non-stuffed plastic bags, I would think.

The tub instructions do not say to not use plastic. Do the instructions say to use piles of mortar?

Why is it called spigot instead of street? I don't have a good theory of how the convention began.

 

[Reach4]

delete

 

[big_rat]

The instructions say to fully level and support the tub with mortar or something along those lines. I can always ask them if they are cool with the idea of using plastic. They seem to be ok with everything I've asked.

How do you feel about the small space around the drain that won't be mortared? Is that normal/ok?

 

[Reach4]

I have never done it, but you are not going to be able to pave the whole area under the tub. You are not going to be able to get the amount just right. With piles, the pile squishes to let the pile collapse to exactly fill the available space. Think of notched trowels for adhesive. The ridges collapse to fill the available space.

I have not done it, but there have been many posts on the topic. They make sense. Try searching using mortar piles tub as a search. Maybe take tub out of the search because you are doing a shower. But the concept holds.

 

[big_rat]

I've done piles for a tub install before but this tub that I'm installing is unique. It does not have a side skirt so I will actually be able to get in with my hands or a stick and shove the mortar all around and under the tub.

 

[big_rat]

Does anyone know if I should do anything with the corrosion on the outside of the copper drain stack? It appears to me that the plumber who installed it didn't clean the flux out that well. Should I wipe down the pipes with something?

 

[JRC3]

Does anyone know if I should do anything with the corrosion on the outside of the copper drain stack? It appears to me that the plumber who installed it didn't clean the flux out that well. Should I wipe down the pipes with something?

Poke it with a screwdriver. Mine had the same problem and had corroded all the way through in spots. It got replaced. ...Pretty much everything in that pic got replaced.

 

[big_rat]

Thanks I poked it and it was solid. A light sanding with emory cloth and it comes right off.

 

[Jadnashua]

Not necessary, but you can if you want...it won't take a lot of time.

A spigot verses a hub is whether the OD of the pipe is designed to either fit into a socket, or is sized to allow a pipe to fit inside of it.

 

[big_rat]

I can get