Do I have to pry up the travertine first?
No! Just get the proper underlayment
I don’t think you do unless the relief pattern is pronounced, meaning very textured. It it’s pretty smooth you’ll be able to cover it with a special liner similar to plywood. Ask your flooring supplier.
in our kitchen we covered an embossed rolled vinyl before the planks were laid. In a bathroom, we laid good one side plywood.
make sure your subfloor is very smooth. Any staples or nails have to be in tightly. Everything shows on the vinyl surface!
does this website runs in Canada?
yes if you want a level floor. I can't say this enough always remove old flooring before installing new if you want a quality floor if you want a crappy floor then leave the old floor down.
This can be installed over travertine. I have seen it done.
You’ll need a 3/4 inch slapstick rod to jimmy the existing tiles loose. Then pour dilute Johnson’s whitewash over surface before laying the new floor down. It works best to do after dark