I've seen underlayment called 1/4", 3/4" etc. which is it?we currently have 3/4" plywood under vinyl in bad condition and are removing the plywood. Will replace w/same. Do we need to put 1/4" over this before putting down sheet vinyl? In order to keep floors even, would then have to use 1/2" plywood over subfloor and then 1/4". Also if 1/16 is left between boards and then use patch to smooth seams,does this mess up expansion between boards. Thanks.

 

Dear LH

To start off with there are many different types of underlayment(hardibacker, Durock, Levelcures, to name a few) so first is if you are replacing the subfloor(the 3/4 plywood) no you do not need to put anything over it as long as it is sound and smooth, those are the two biggest requirements for installing sheet vinyl. And yes you would use patch to smooth the seams but you need to use a skim with a flexible additive in it. The two main rules in sheet vinyl are sound and smooth because any imperfections on the subfloor will "walk through" or show in the vinyl.

Hope that helps,

Kevin