Roughing 1/2" Copper for Tub Tile

[Chuck B]

I am going to run 1/2" copper pipe for my tub spout, single handle hot-cold shower/tub faucet, 6 in 1 mixer for the main shower head, a body spray, and a separate hand help sprayer...all Moen behind 13" square porcelain tile.

Will screw Hardibacker to studs, tape and thinset seams and caulk bottom gap by tub lip with silicon.

How do I calculate the "horizontal" (sweating 1/2" copper) placement of the above fixtures so that they attach properly outside the ceramic tile, which is over thinset and over backerboard. Is there much play in it?

Also perplexed why "do it yourself plumbing how to books" show a galvanized pipe to the tub spout. Stronger than copper? Wouldn't a brass nipple be better? Doesn't galvanized interact with copper anyway?

Thanks guys!

 

[Reach4]

Also perplexed why "do it yourself plumbing how to books" show a galvanized pipe to the tub spout. Stronger than copper? Wouldn't a brass nipple be better? Doesn't galvanized interact with copper anyway?

You are correct on all counts on the galvanized. However the best deal is to put in a longer galvanized nipple until the finished walls are done. Then replace that with the correctly sized brass nipple.

 

[Sponsor]

 

[Terry]

Many plumbers will use galvanized because of cost. Every morning when the tub is used, you will get a little burst of rusty water.
I use either brass or copper. I don't carry galvanized on the truck.

The Moen spec sheet and instructions will have the allowable setback from the finished surface. There is some leeway. I like to be somewhere in the middle, because I never know exactly how much space the backer and tile will take. It's always a guess.

 

[Chuck B]

Many plumbers will use galvanized because of cost. Every morning when the tub is used, you will get a little burst of rusty water.
I use either brass or copper. I don't carry galvanized on the truck.

The Moen spec sheet and instructions will have the allowable setback from the finished surface. There is some leeway. I like to be somewhere in the middle, because I never know exactly how much space the backer and tile will take. It's always a guess.

Thanks a lot Terry and Reach! Big help great advice as usual!

 

[Sylvan]

If the nipple is temperately being used why not black steel?

 

[hj]

Because we seldom carry black steel and would not have much use for it after the tub was done.

 

[Jadnashua]

It sounds like you may be having a lot of potential outlets from your inlets...are you sure you'll have enough volume to do what you want? While you can get more volume than this from a 1/2" copper pipe, the copper organization highly suggests you design things for a maximum flow rate of 5fps with a hot line, which on a 1/2" pipe is 4gpm! Now, you'll have some cold coming into that mix, and they allow 8fps with it, but that could be short-changing your showerheads. Going beyond that recommendation results in noisier pipes, the potential to erode them from the inside, and loss of pressure through friction.

 

[Terry]

I
Also perplexed why "do it yourself plumbing how to books" show a galvanized pipe to the tub spout. Stronger than copper? Wouldn't a brass nipple be better? Doesn't galvanized interact with copper anyway?

Thanks guys!

Many "how to" books are written by writers that ask questions of people in the trade, and then try to picture what they meant by it all.
It's rare that I follow much in the books. Some of the information is old, or just not done.

 

[Plumber69]

If the nipple is temperately being used why not black steel?

It's more common here. When finishing there will be rust built up which will stain tile grout

 

[Plumber69]

It's more common here. When finishing there will be rust built up which will stain tile grout

I reuse the same nips and cap

 

[Terry]

If the nipple is temperately being used why not black steel?

They weren't talking about a nipple stubbed out during the rough, and being replaced at trim. Some plumbers use steel nipples from the valve body with a steel 90. Any steel to the tub spout will give you rust first thing in the morning. It works, but why do it?