For a kitchen sink installation PEX is typically run inside the stud wall with a copper Stub out fitting which is attached to a stud at the desired point for the angle stops.

PEX should never be run in an exposed location because PEX will deteriorate from prolonged exposure to ultra-violet light.

lazypup,
Thanks, this has to come through the floor...a remodel. The way you have described it...sounds like the transition would be inside of the wall. I'm not familiar with the code,but I thought I remembered hearing that there should be not pex joints inside of a sealed space.

A PEX fixture stubout is a PEX x Copper Transition that has a short section of copper pipe bent in a 90deg angle and it has a flat mounting bracket that is nailed to a stud inside the wall. One end of the copper pipe has a PEX connector and the other end is a straight section of copper pipe which is capped on the end. When installed the capped end extends out of the wall to provide a standard copper stubout. After the system is installed and pressure tested the stubout is cut to length and copper x 3/8compression adapter or an angle stop is installed on the copper pipe. by necessity the PEX connection remains inside the wall.

If you would like a copy of the PPFA(Plastic Pipe & Fitting Association) Installation handbook you can download it in PDF format from this website:

http://www.toolbase.org/Design-Construction-Guides/Plumbing/Plumbers-Installation-Handbook

LP, thanks for the link to the handbook. I understand exactly what you mean on the stubout. Since I have to come through the floor I will have to find a method of securing the copper in the basement. That will give me something that doesn't move around under the sink. So, what a few have posted on this site is incorrect? Pex fittings, by code, are allowed in a closed wall?

Quote"PEX should never be run in an exposed location because PEX will deteriorate from prolonged exposure to ultra-violet light."
Lazypup,
I thought that PEX would deteriorate if use outside due to sunlight UV. It should be OK for exposure inside the home where there is no UV. Please correct me if I'm wrong.

Regards

Joe

The installation manual cautions that even when run in a basement it must be protected from UV coming in the windows..PEX tubing and manifolds must be installed where they are protected from any direct sunlight coming in a basement widow or harsh UV exposure from artificial lighting sources. When run under a raised structure such as a mobile home you must have skirting or provide protection against reflected sunlight.

Also, for new construction in my jurisdiction you can't use a PEX supply tube on a watercloset if the bathroom has a window.