We just purchased a multilevel home built in 1969, and I have a question about our bathroom vinyl floor. The bathroom sits on a concrete slab and a blue stain extends about 3 feet out from the front of the toilet. I will follow your advice and have the floor tested for asbestos before replacing it, but I wonder if you have a theory why the stain would only appear in the toilet area?

Thanks for answering the email questions I sent you about the staining situation. Since you didn't see any blue staining in the toilet tank, we can rule out a toilet bowl cleaner's involvement. The toilet is not leaking from underneath through the front unless the floor slopes downward in front of the toilet.

Typically leakage comes from the side or back of the toilet, not from the front, so any stains or discolorations that I have seen around toilets associated with concrete floors are normally found near the back or sides. These areas are prone to a higher concentration of moisture (sweat) after someone takes a shower, which may accelerate or contribute to the staining process.

This moisture, the flooring mastic (glue/adhesive), and the minerals present in the concrete could possibly create a chemical reaction, causing staining to just under the floor's top clear finish.

I'm not sure exactly why this staining occurs, but I suspect that a combination of moisture from the toilet, moisture in the concrete, and the mastic reacting to the minerals in the concrete.

For that reason, I'm convinced that resilient flooring should not be used in a bathroom environment with a concrete subfloor. I also don't believe that Pergo (or similar flooring products), wood, or carpet should be used in this environment, especially if there's a shower.

In a basement bathroom or any bathroom on a concrete subfloor, I recommend tile such as unglazed mosaic, pavers or quarry as a floor covering.

Since floor tiles are cold in general and will become even colder when placed on a concrete slab, I recommend a floor-warming system by SunTouch that will keep the tiles and your toes toasty warm. I installed this system in our own bathroom.

I like the SunTouch system because it uses an extremely flat orange mat that increases the overall finish floor thickness by only 1/8 inch to 1/4 inch, depending on the thickness of the thinset applied. It comes in both 120 or 240 volts and includes all the parts necessary to complete the system: wall-mounted thermo-stat, floor temperature sensor, and double-sided tape to secure the mat. The system can be installed directly onto a concrete slab floor. To learn more about the product, go to www.suntouch.net or call them at 888-432-8932.

You also mentioned in your email that staining is also located on the front sides of the toilet. It's possible that the staining is not from a leaky toilet, but that can only be confirmed by removing the toilet and inspecting the wax bowl ring for damage and around the toilet flange to see if it is cracked.

I suspect that the stains came from the rug without a rubber backing that fits around the front of the toilet. Perhaps the toilet overflowed, soaking the rug and it bled, staining only the top surface of the floor.

As I said before, you won't know for sure until you pull the toilet.

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C.R.S., Inc. · Spokane, Washington · USA