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When running CPVC supply lines for a sink, how should they be anchored before popping out of the drywall? I know with copper you can use drop ear elbows which are mounted to a backer

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But with CPVC supposedly "CPVC expands and contracts more than copper tubing, especially in the hot water line. A 10-ft. piece of tubing can grow in length by as much as 1/2 in. Never butt the tubing against a framing member. Leave a gap, as shown in Photo 8, especially in a long run. Runs longer than 30 ft. require a U-shaped detour about 1 ft. on a side somewhere in the length to allow for expansion and contraction.

When drilling holes through framing members, you'll also need to give the piping some space (Photo 9) to allow the longer horizontal and vertical tubing to move."

That would seem to imply that you'd not want to have the elbow anchored to a piece of wood, yet in the picture on the page, it seems like this is exactly what they do.

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What's the proper way to terminate the CPVC supply lines?

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    We used to use the drop-ear 90°s but we were careful to loose strap all the pipes and drill oversize holes through framing members, giving it room to bow when it grew. I don't remember ever making expansion loops.
    – Jimmy Fix-it
    Aug 20, 2016 at 2:12
  • Jimmy that should be an answer I have had the same experiance with cpvc.+
    – Ed Beal
    Aug 13, 2018 at 14:15

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If its a short length of pipe and it's got a little wiggle room it shouldn't be an issue if you solidly mount them, but everything already mentioned (30' length of pipe needs expansion loops, over sized holes are good, allowing for some play/movement of the pipe is recommended) is good advice.

And you don't want the pipe flopping around inside the wall. It will make attaching the angle stops and supply lines for the faucet a PITA later if they move around too much.

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You are right, probably not a good idea to do that. I would use pex instead because I've had more leaks with cpvc and I would use strapping or pipe hangers if I was worried about pipes hanging loose.

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