All mold cares about is humidity. If relative humidity is over like 55-60% then mold will grow. That's it. Stale air and lack of airflow help to keep humidity high because air is not being circulated evenly. You can get pockets of high humidity in certain areas. So that will add to the chances of mold.
this post was submitted on 14 Mar 2025
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Explain Like I'm Five
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Technically it’s a combination of absolute humidity and temperature. Bathrooms can be prone to mold even if they’re not any more humid than the rest of the house, because metal plumbing can conduct heat out of the room into the ground—causing the room to get cold enough for moisture to condense even if the water fixtures in the room aren’t in use.
Yeah, for sure. Relative humidity is influenced heavily by temperature so i kinda baked that into my answer haha.
Here's the book of standards for indoor air quality published by ASHRAE (American Society of Heating, Refrigerating, and Air Conditioning Engineers):
https://www.ashrae.org/File%20Library/Technical%20Resources/Standards%20and%20Guidelines/Standards%20Addenda/62-2001/62-2001_Addendum-n.pdf
And this is the relevant bit for this situation:
Apartments and houses are designed for air flow. You don't need a gap in your door to prevent mold. Mold will grow despite that if you live in a city that has high humidity.
Everyone should watch for mold. Check around windows. Behind the toilet tank. Above and around the shower. Wipe with bleach often.
You can also get a dehumidifier if it becomes a problem
Bleach doesn't kill mold, and actually causes it to release spores. Use concrobium (or a similar product) to properly kill it.
I've heard vinegar is better at killing mold than bleach
Not bleach. Use mold control spray. Bleach doesn't kill the mold deep in the drywall, and sometimes not in the cracks of the paint.
I would get a dehumidifier before resorting to wiping with bleach often. If you ever see mold, you already have a humidity problem. This may be isolated to your bathroom due to extra moisture from showers, but it's still a problem that needs to be addressed. If it's just the bathroom, a new shower fan (or just using the existing one) could be enough.
I don't understand what you mean when you say you "don't live there" ?
Regardless, if you consider mold in general then the room which most typically gets mild growing is the bathroom, because it's moist and warm which is perfect condition.
It doesn't take much to get mild growing in other places too though. If you have moisture in the air then mould could happen.
Good ventilation helps prevent mould because it lets the humid air created from normal activities like cooking and washing escape and be replaced with drier air from outside - assuming you live in a climate that doesn't have crazy humidity.
As in, I don't live in the apartment, I'm living somewhere else currently. So, nobody uses any water, does any laundry, cooks etc. there.
So I don't understand how it could become humid inside my apartment.
Fair :) But on that basis why are you wanting to block things off if neither you nor anyone else is living there?
That wasn't my question
If a pipe breaks or just starts leaking or water comes in from a different apartment and you aren't there to catch it you can get mold.