Add Full Bath using PEX - DIY Chatroom

cibula11 · 10-01-2009, 10:41 PM

After plumbing quotes around $4000 to add a full bath we've considered doing the work ourselves. Our house currently has copper, but we would like to use pex to supply shower, sink, and toilet.
My questions refer to running pex to the different areas.
1.)Do I need to use a PEX manifold added onto hot and cold water lines and then PEX to each fixture?
2.)Where is the best place to make this transition to PEX?
I3.)f using a manifold do I need to be mindful of the sizes of PEX to each fixture and the order in which they are run?
4.)Is PEX typically ran to a copper stub out near each fixture so that shutoff vavles can be used and the PEX is not exposed (especially on a pedestal sink or toilet)?

(I believe the largest copper we currently is 3/4")

Daniel Holzman · 10-01-2009, 11:15 PM

1) No, you don't need a manifold, you transition from copper to PEX using a sweated on PEX transition piece.

2) You can make the transition anywhere you can sweat on an adaptor.

3) You need to use the appropriate size PEX regardless of whether you use a manifold or not. Typically 3/4 inch for the main line, and 1/2 inch to each fixture.

4) There are PEX shutoff valves available. You can use crimp copper valves if you prefer. I use crimp angle stops specifically designed for PEX, and use braided stainless steel for the final connection. The only reason to worry if the PEX is exposed is if you don't like the look, or you are worried that Edward Scissorshand is loose in your house, and will damage the PEX. He doesn't live at my place.

**thekctermite** · 10-02-2009, 12:59 AM

Daniel covered it pretty well.

PEX is great stuff and is easy for DIYers and plumbers alike.

One consideration with PEX that a lot of people (including plumbers) don't know about is that you have to keep it away from sources of heat such as can lights, which are common in bathrooms. Most PEX manufacturers recommend at least 12" vertical clearance between the heat source and the PEX, and at least 6" of horizontal clearance.

cibula11 · 10-02-2009, 08:54 AM

Thanks!

Is the best place to tie into my supply lines typically near the water heater? If so, I would most likely need to cut a straight run and at a "T" fitting. Is this the easiest way or is there a better option?

Will it matter the order in which I run the lines i.e. sink first, then shower, then toilet supplies?

You mentioned I don't need a manifold, but would that be the best option since I'll have a cold line or sink, shower and toilet and then hot line run for shower and sink? Just wanting to make this as simple as possible.

Daniel Holzman · 10-02-2009, 10:41 AM

I redid my entire house in PEX because the copper pipes all had pinhole leaks due to acidic water. There are a few sections of copper left, areas that I had previously replaced with copper and didn't feel like breaking up a wall to replace with PEX, but about 95 percent of my house is PEX, starting at the pump.

You can replace as much or as little as you need to. I have been to houses that use manifolds, I don't know that they save any money or time, but certainly they are an option. One advantage of a manifold is that you can shut down an individual fixture without turning off the whole house. They use more pipe than a traditional run, and may be more appropriate for new construction, where the walls are open and the pipe can be installed in chases.

I recommend that you get the appropriate PEX tool for the specific type of piping and fitting you are going to use. Since I used Wirsbo tubing, I have the Wirsbo expander tool. Cost about $300, but it beats renting the tool at $50 per day.

cibula11 · 10-02-2009, 12:49 PM

So basically I can run pex from the hot water line and cold water line coming out of the water heater, and then to each fixture?

Daniel Holzman · 10-02-2009, 01:46 PM

That is exactly what I did. Just make sure you use potable water PEX, not the PEX designed for radiant heat applications. Also, if you use the Wirsbo tubing, you will have the choice of plastic (polysulfone) and brass fittings. The theoretical advantage of the brass fittings are that they (in principle) can be reused if you ever need to cut the pipe off to add a T, reroute, or some other purpose. In my experience, in order to get the pipe off the fitting, you need to slit the pipe with a razor blade tool, and if you even slightly nick the brass, it will not seal properly, so I never reuse any fitting, brass or plastic.

I prefer the plastic fittings now, since I have acidic water, I am somewhat concerned about acidic damage to brass (see the Zurn lawsuit regarding brass fittings and PEX).

djrussell · 10-02-2009, 02:15 PM

Quote:

Originally Posted by Daniel Holzman

2) You can make the transition anywhere you can sweat on an adaptor.

take note of that comment. you'll still need to do some soldering or have someone do it. this is what drove me to do my bathroom work in copper. i saved by not having to buy the pex tool and learned to solder in the process. i'm not too bad at it now.

it does take more time and work though just in prepping the joints.

WaldenL · 10-02-2009, 06:55 PM

Actually the sharkbite connectors can grab onto copper just fine. You don't have to solder on a connection, you could go with all push on if you wanted to.

cibula11 · 10-02-2009, 07:09 PM

Yeah I think I'll have to soder something. Since my existing plumbing is copper and I'll have to tie into it, sodder is most likely inevitable. Is there any other sort of "code" requirements that I need to be mindful of as I run pex?

Is cutting the straight run of copper in the middle okay to do? The only L fitting is really impractical because of where it is located.

WaldenL · 10-05-2009, 10:09 AM

You can cut a run of copper in the middle, no problem. Just stick a tee in there and pull the pex off the tee. As for the soldering, I'm not arguing against it, but you can use push-on connectors on the copper too. Probably simpler to solder on the tee and then pull pex off from there.

djrussell · 10-05-2009, 12:31 PM

that's a good point i forgot to mention. you could use a sharkbite or similar to transition between copper and pex. no soldering necessary. i talked with my local plumbing inspector and he didn't recommend using them inside walls. i went with the tried and true soldered connections.

WaldenL · 10-05-2009, 12:33 PM

My understanding is that the push-ons are approved for hidden (in-wall) installations, and even underground installations. But what really counts is whether the inspector will pass them. :-)

cibula11 · 10-06-2009, 04:10 PM

Let me run some things by you all and let me know if I'm on the right track.

I'll add a "T" fitting to my hot and cold water 3/4" copper about 3-4 ft from my hot water heater. I'll run 3/4" pex to an area near the bathroom where I will send a 1/2 PEX to supply the tub, sink, and toilet.

Does that sound right. Do I need to use 1/2" for sink or can I get away with something smaller?

WaldenL · 10-06-2009, 04:12 PM

Plan sounds reasonable. A 3/4 feeder to the bathroom and then 1/2 to each device. You want to use 1/2, nothing smaller. And remember, 3/4 pex is a lot harder to bend to your will than 1/2 is (learning that the hard way right now) :-)