I'd like to install the standard Allure luxury vinyl planking (with an adhesive grip on two ends) in an upstairs unit of a fourplex in which I took out carpet. I'm concerned about noise issues travelling to the downstairs unit and am investigating putting a roll of cork over the MDF boards that are on the floor. (Haven't been able to figure out a good way of using the GreenGlue for flooring which is supposed to be good between sheetrock layers in walls.) Should I put cork under cement board for installing this product, or should the cork go over the cement board, do you think? My husband went out and found the warranty info on the Allure and apparently putting an underlayment under the product voids the warranty?! My bigger concern (over the 5-year warranty in a commercial setting) is a good installation and I'm considering taking this product back to the store before I even install it and finding another product for this LivingRoom-Kitchen-Bath project. Also, after reading this discussion, I'm wondering if we should put the toilet down first and then caulk around the bottom of the toilet in the bathroom, instead of putting the vinyl under the toilet and not installing under the frig and stove in the kitchen, since it's supposed to be free-floating. Is the Allure Ultra product click-lock and therefore better? Do ya'll have flooring installation ideas, tips, warnings, or advice for me here?