Do You Have To Put Anything Under Vinyl. Most of todays luxury vinyl tiles are fully waterproof which means you wont have to put a damp screen to prevent moisture as a part of the underlay. Others dont care and just a few recommend it.

When Underlayment Is a No Go Vinyl flooring installation with tiles and planks can be simple even if using underlayment. With uniform dimensions and edges these sheets are pretty much weightless. Vinyl floors under 4mm should be installed right over the subfloor.
Lots of houses have vinyl siding.
Vinyl floors are designed with a base layer making the addition of underlay pointless. Vinyl floors under 4mm should be installed right over the subfloor. Vinyl tile is available in three main styles with VCT or vinyl composition tiles peel and stick tile and luxury vinyl tile. With thinner vinyl flooring construction adding a foam underlayment can effect the locking system strength.