Homepage › Forums › Fix-it Forum: Home Improvement & Do It Yourself Repair Forum › used floor tile This topic contains 1 reply, has 0 voices, and was last updated by the warm floor center 21 years ago. Author Posts September 26, 1997 at 11:38 pm #10548 Gina Wanick I have alot of used 12×12 floor tiles with the concreteleft on the back. Do I have to remove the old concrete,or can I leave it on. It would take forever to chip itoff. September 27, 1997 at 9:59 am #76381 the warm floor center yes you should. the tile will be harder to installand will not set level.rjb Author Posts You must be logged in to reply to this topic.