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I would like to tile a concrete floor in a 4-season room. The floor has two potential problems: it was painted several years ago and I’m not sure how to get the paint off so the tiles adhere; and more importantly, the floor isn’t smooth. The original floor (poured concrete) is nice and smooth, but the room was enlarged 15 or so years ago and the ‘new’ concrete is very rough and not level compared to the original floor. so, is there a way to create a smooth surface by grinding down the rough concrete or should I just pour a thin layer of mortor (?) on top to level the floor? And do I need to do anything about the paint? TIA.
…tom
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Tom, If the paint is good ie, not flaking off or easily scraped off, you are probably fine to tile right over it. Use a good thinset mortar perhaps with a bonding agent. You could also 'prime' the painted floor with something like WeldBond glue, which acts like a bonding agent. If the paint is flaky or suspect it is worth going back to concrete. Use either paint stripper or bush hammer the surface to get back to 'crete. Regarding the un smooth surface, if it is only a bit uneven, your mortar bed could be thick enough to level it. If it is really uneven you could try a self leveling concrete (expensive) or grind it (Really, really dusty).
*There are a number of methods to professionally remove paint from concrete and at the same time prepare it for resurfacing or tile work - shotblasting, water blasting, carbide cutters, diamond grinding, etc. Depending on your geographic location and availability, they may be cost prohibitive."Pouring a thin layer of mortar" is not the answer as thin overlays are a major problem unless a polymer concrete or some of the self-leveling (as mentioned).I always view paint as a "bond-breaker" but there may be some overlay products capable of bonding to it for the long haul.You don't mention the size of the room. Disk grinding sure is messy, but in a smaller area with some dust controls in place (vacuum, exhaust fans) it is certainly viable and cost effective.I've removed paint from garage floors with just high power water spray from rented units - obviously had to control water and have to wonder how good the paint bond was to begin with. Can you control water in your space?Just some more thoughts. Randy
*Call in a concrete grinding specialists. I just had alot of grinding done on a 4500 sf floor. They first came through and grinded off all of the paint that the painters sprayed on the floor, then ground the humps and floated any low spots with Ardex 15 self leveling patch. Tile guys use it all the time to level concrete for their tile. It costs .15/sf to grind off the paint, 55.00/man hour to grind and 1.60/sf to Ardex 15. So. California prices. Look under concrete contractors in the yellow pages. GW