This is going over a concrete subfloor in a basement. Contractor is saying that floor is not level. What can I put to level floor ?

Hello Reluctant renovator and thanks for your question. Yes, the Style Selections Jute Oak LVP should be installed on a floor that is level 1/8" on a 6 foot span. First, the subfloor must be cleaned of all dirt and debris, then filled using a suitable commercial grade patching or leveling compound. Finally, cover the concrete with a 6 mil polyethylene plastic vapor barrier, then install the flooring over the top. For more information regarding subfloor preparation, installation, or warranty, please review the Installation and Warranty Guidelines (found in each carton or on the product page of the Lowe's website). Thanks again.