Any Problem Installing Laminate Flooring Directly (no Underlay) Over Vinyl Kitchen Floor That Is Over Dry Wood
February 19th, 2010 | 
Author: The salesman says to use a plastic sheet and/or thin foam underlay but offers no persuasive reason to do so other than the floor might be quieter. My subfloor is dry wood over a full basement. I can see no valid reason for the added underlay and expect to install without it unless someone can offer a good reason for its use.
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I think the thin foam does two things. One ii helps keep any small imperfections in the underfloor from causing a problem but more importantly, the laminate floor needs to be able to expand and contract. The foam underlayment that I used with my Armstrong laminate floor was pretty cheap and the top surface was very slick. I’m sure it gives the flooring a better chance of adjusting to different temperatures
Just lay down some rosin paper first. Whatever you do, don’t nail or glue it down! The flooring needs a certain amount of freedom of movement or it will lift and buckle. The interlocking tonque and groove system is enough to keep it from seperating as it becomes a co-hesive unit when completed.
will keep floor from sliding
when you install floor it does not go tight to the wall
Sorry for this non-answer but you might get an answer on the hgtv.com forums. There are all kinds of crafty do-it-yourself people and professionals there to answer your home repair questions.
Our underlay is not thick enough, and our basement has our family room in it. You can hear every step someone upsatirs makes. It is so annoying!
depending on the age of the vinyl and how it was installed, the new flooring might rip up the old. it is best to install directly to solid wood flooring or use the underlay