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Mildew on non-vented bathroom ceiling. How to ventilate?

8 years ago

last modified: 8 years ago

We recently purchased an older home (1950's) that we plan to knock down and build on eventually. Until we get everything situated (plans, permits, etc.) taken care of, we are renting it out. It was a mess when we took it over so we did a lot of cleaning and had it re-painted. After our most recent tenants moved out, they mentioned that there was some mold/mildew on the bathroom ceiling. There isn't any venting in there and I'm guessing that is what is causing the problem.

What is the best way to mitigate the problem and provide some sort of ventilation (without doing anything major structurally) to keep the problem from coming back?

Does Kilz work as a mold deterrent in this manner to get rid of what's currently there?

Picture of bathroom. There is a window in here but no other source of ventilation if the door is closed.

The corner of the bathroom where the paint is peeling. Is this where the moisture is "collecting"? We had the whole house, walls and ceilings, painted not more than 3 months ago

Close up of peeling paint and mold

It's all over the ceiling

Close-up of mold

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Comments (6)

anitamo
8 years ago
last modified: 8 years ago
Have you looked in the attic? Was the roof replaced recently? Is the bathroom the only ceiling affected in the house? Moisture breeds mold, so water is getting in somewhere. And you would need a vent, too.
User
8 years ago
last modified: 8 years ago
Install a vent fan on the wall above the window. 4" hole in the wall and a deflector/flapper closer door on the outside. Mount the van in a box to the 4" vent pipe. Wire to the light(most difficult part).

Clean off the mold/loose paint(scrub it with Bleach/water. Let dry, prime with BIN or even Kilz. Let dry. Paint.
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PRO
Cabot & Rowe
8 years ago
Paint will not stop mold. Mold needs water, food, and air to grow. By eliminating the water, you'll stop the mold. Venting is the way to accomplish this task. Check your local code for how close to the window a vent is allowed to be placed.

If this place will be a rental in the future, hard wire the vent to the room light to be assured the vent will be used.
energy_rater_la
8 years ago
install a bath vent fan. clean molded areas with tsp.

run bath fan for half an hour after showering.

mold needs moisture and a food source.

eliminate the moisture. paint damage looks like from inside the room,

not from above.

best of luck.
User
8 years ago
last modified: 8 years ago
A typical bathroom fan only exhausts so it can't provide ventilation air (i.e. outside air) but it removes moisture laden air and pulls in dryer make-up air from the adjacent room. There are bathroom fans that do provide outside make-up ventilation air that passes through a heat exchanger.

As a temporary solution, you could open the window a bit or clean and repair the ceiling so it is very smooth and paint it with a semi-gloss vapor barrier paint with a mildew resistant additive. It wouldn't hurt to wash it every few months too. Flat or textured paint would speed the growth of fungus.

But I suspect you will need to replace the ceiling and that is the time to install an exhaust fan. Of course you could install a simple exhaust fan through the wall near the ceiling with an humidistat and timer.
sdello
8 years ago
Clean as recommended above and repaint with this

http://www.rustoleum.com/product-catalog/consumer-brands/zinsser/cleaners-and-mold-and-mildew-proof-paints/perma-white-mold-and-mildew-proof-interior-paint

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