Why is LVP better than vinyl sheet? It seems more expensive and less waterproof with no adantages?
It’s much easier to lay, particularly in large rooms and when it’s not a perfect rectangle. Depending on the brand, it also can have a much thicker underlay. With sheets if it gets torn or if you have to do something to the subfloor you really have no choice but to replace the entire sheet, which typically is adhered with glue and difficult AF to remove. LVP can be entirely removed and then re-laid, which came in super handy for us when we had a sink flood.
It depends on the product. Sheet vinyl flooring can either need full glue, perimeter glue, or no glue.
I have thick, cushion vinyl flooring in my master bedroom extension and it required no glue, it was just cut, rolled into place, and that's it.
It's quite thick, around 5mm, so it's durable and very comfortable to walk on barefoot. Mine is matte grey, so you barely notice it's there, which is my personal esthetic preference for this particular space.
The major downside with loose-lay vinyl is that you really can't be sliding furniture around on it because it will shift and create bumps. We did this moving a dresser and now make a point to get help to fully lift anything heavy that needs to be moved. That said, I probably wouldn't want to be dragging furniture over a lot of LVP either, so it might be a moot point.
I initially chose cushion vinyl as just "for now" flooring because it was so cheap and the supply chains out here were still a disaster during building, plus I was off the island and had no option to see anything in person. But I've been tremendously surprised with how much I really, really like this flooring and have no intention of changing it until I have to.
After this install, I would probably choose cushion vinyl over LVP for most spaces.