I recently discovered a very slow toilet leak (only when flushing), which has dampened the bathroom floor, and dripped onto the basement ceiling, where there is now a pretty mold spot.

A restoration company gave me a quote to remove the floor in the bathroom, the affected area of the ceiling, and 12 inches (31cm) of drywall along the base of the bathroom floor.

My question is: How important is it to replace all the drywall (both on the bathroom walls, and in the basement ceiling)? The quote was to remove the area with > 13% moisture.

Is this strictly necessary?

I'm concerned about the structural integrity of the wall and ceiling, as well as any possible health implications, since the leak was used toilet water. As the water had to wick into the walls, from the floor, I suspect the water there should be "relatively" clean, but the leak has also been going on for quite some time apparently, so who knows what's been growing in that water.

  • what kind of flooring?
    – DMoore
    Jul 29, 2013 at 5:00

1 Answer 1


If there is mold on the basement ceiling, it is highly likely that there is mold growing behind the drywall where water has wicked up the bathroom walls -especially if this has been an ongoing, untreated problem. I personally would not try to save money at the risk of leaving mold growing in that area.

Mold can trigger a host of health problems, some very serious. I once met a woman who had a condition where she was debilitated by sensitivity to perfumes and artificial fragrances (contact or exposure could cause her to be be bed-ridden for months at a time. The weekend I had met her was the first time in three years that she had left her house (her home was a strictly controlled environment - air filters, hermetically sealed rooms, the whole nine yards. She explained that her condition was triggered due to living in a basement for about 8 months where mold was present in the ceiling (she didn't find out about the mold until after she came down with the health problem. I know this is an extreme example, but it is one example of what can happen if mold is left unabated.

Sorry about the verbose response, but take the repairs seriously and don't skimp out just to save time or money. Your long term health is worth the up-front cost of repairs.

  • If I'm not mistaken, once the water source is removed, the mold will stop growing, and die. It's unclear to me if there will still be a health risk after I have removed the visible mold, and the water.
    – Flimzy
    Jun 28, 2013 at 19:23
  • 2
    @Flimzy Depending on how humid it is where you live, the mold could continue to grow in the paper backing of the drywall.
    – John Smith
    Jul 29, 2013 at 23:24
  • @Flimzy It's dangerous to think mold will 'go away'. Instead at best it will spore over, going into a state where it can live for years until another bit of humidity reactivates it. You need to mechanically remove as much of it as you can, and then use a dilute solution of bleach to try to kill the parts you can't see. See this guide for more detail: cdc.gov/mold/cleanup.htm Aug 28, 2013 at 16:27

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