Bathrooms can be very wet and humid places.
Water gets splashed onto floors, shower walls with closed curtains or glass enclosures stay wet for long periods of time, and wet towels get hung to dry.
All these things can account for a lot of humidity in a bathroom. This is especially the case if there is no exhaust fan—-or if the fan is not functional or doesn’t get used—or not used enough.
These conditions can be perfect for growing a good batch of mold. While some of this will be apparent on grout lines, the corners of the tub and shower, and on walls and ceilings, the condition can be concealed by recent painting, caulking and cleaning—-as is common when the home is put on the market.
The inspector wants to know how the bathroom is doing moisture wise. He or she wants to know if a month after the inspection, whether all the painted-over mold is going to break through the surface like some creature in a science fiction movie.
There is usually one place that gets overlooked in the quest to eliminate this unsightly condition prior to sale. This is the coldest and wettest place in the bathroom. Even under the best of conditions it can be a good habitat for mold growth. But because of this “naturally conducive” environment it is also a good indicator of the bathroom humidity in general. I s a good barometer for leading the inspector to look more carefully in other areas of the bathroom.
This “place” is the underside of the toilet tank.
Bathrooms with poor ventilation or high humidity (due to the many causes previously discussed) will often have toilet tanks that look like this. How about your toilet tank?
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Charles Buell, Seattle Home Inspector
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Hepner says
We moved into an apartment mid April in Renton and I noticed mold like this (worse actually) under the toilets and on the wall behind the tanks. What do I do? I told the office about it already when we first moved in about two weeks ago. It’s so bad that bits are starting to fall down on the floor under the toilet tank.
Charles Buell says
Being a rental, the fix is going to involve whoever owns the building as well as your own use of the building. The source of the moisture will need to be located and corrected and then the mold can be cleaned up by a qualified party as necessary.
Hepner says
Thank you! I’ll have to contact management about it again.