I am interested in installing sheet vinyl (either the Congoleum vinyl or the Mannington Sobella fiberglass product) in two rooms that currently have the tile-look laminate flooring. One of the rooms is the kitchen, where the subfloor beneath the laminate is plywood and that room is over the basement; the other room is a family room which is on a slab foundation, and the laminate and its supposedly cushioned underlayment is directly on top of the cement slab.

Originally I assumed that I could simply have the existing laminate and its underlayment removed and apply the vinyl flooring directly to the plywood subfloor in the kitchen, and as far as the family room my plan was to have my contractor install a floating plywood floor because due to health issues I cannot walk directly over a cement foundation, and then install the vinyl on top of that new plywood surface. However, the salesperson at the Mannington showroom where I saw the Sobella told me that sheet vinyl cannot be installed directly over a plywood subfloor because the surface is not smooth enough -- and that a layer of Wonderboard would need to be installed over the plywood and then the sheet flooring would be installed over that.

Is the salesperson correct about sheet vinyl not being able to be applied directly over a plywood subfloor?

I also asked him whether the new flooring could simply be installed over the existing laminate flooring without having to pull that up at all, and he said no that could not be done because the surface has to be absolutely solid underneath the vinyl with absolutely no give or flexibility whatsoever to it. Again, correct or incorrect?

When I raised this question with my contractor he disagreed with the salesman and said that he has often installed sheet vinyl directly over a plywood subfloor and as long as it is level there is no problem. So I would love to get opinions from those who have installed this product as to whether a plywood subfloor by itself was sufficient or whether the extra layer of Wonderboard is truly necessary. Many thanks!

This post was edited by My4thGarden on Wed, May 29, 13 at 8:14