Q: Our cat frequently urinated on our basement concrete floor, which now has a strong urine smell. I’m in the process of getting the house ready for sale and have tried everything I can think of to remove the smell from the concrete. Do you have any suggestions?
A: This was a new one on us, so we asked Terry Collins at the Portland Cement Association if they had any experience with removing cat urine. It turns out that this problem isn’t as unique as one might expect. Removing cat urine isn’t any different than removing human urine from concrete. So here are a couple suggestions.Place some clean cat litter on the floor. Using a wood block, scrub the cat litter back and forth to open the surface of the concrete a little bit. Then, leaving the litter on the floor, place a mixture of half bleach and half water on the floor, scrubbing it in. Leave it overnight, removing the residue in the morning.If that doesn’t work, try dissolving 2 pounds of trisodium phosphate (TSP) crystals in 1 gallon of hot water. In a separate, shallow enamel pan, mix 12 ounces of chlorinated lime to a paste-like consistency by adding water slowly and mashing the lumps. Pour the TSP solution and the paste into a plastic container and add enough water to produce 2 gallons of solution. Stir well. To the concrete surface, apply a 1/4-inch-thick layer of this clear top liquid, converted to a thick paste by the addition of powdered talc. After it has dried, scrape it off and remove the residue. This solution will corrode metal and bleach fabric, so be careful. This method also will remove some very tough stains on concrete.