I am installing my PEX plumbing runs.  Most of it will be in the I-joist and covered…but I will originate all the runs from a manifold.  Since PEX is UV sensitive, do folks install these runs in the wall studs or cover them with a “box”?  Installtion is in a utility room, with a window and door.  Wethead?  I have heard of brittle PEX from perhaps too much exposure.  Obviously safe thing to do is cover it up…just curious what is done every day.