I once had to fit a long copper pipe under a section of wooden floor. It needed to go through joists and I ended up having to cut it into sections and solder it all together.They use them in some new builds. Pressure test them to make sure they is ok. Am not convinced they is betterer than copper pipe. Cheaper. Copper dun't last foreverer but eye prefer it in castle hippo. Eye has one length of copper pipe that eye knows of. Runs under me dining room floor to the kitchen rad. Eye plan to remove it and drop a new pipe from upstairs into the kitchen instead.
Nightmare, plus I nearly set fire to some crud under the floor boards.
I is not a plumberist!!
Plastic was not around then otherwise I'd have used it, plus plastic is quite bendy so the whole job might even have been possible in one length.
House sold a while back and wasn't leaking then!