Apparently, the contractor let the drywall get soaked while sitting on palettes during monsoon season, and since the roofing wasn't done there were inches of standing water that resulted in black mold.
They just drywalled right over it. In the US. In 2018. In a luxury condo.
So, you never know what nonsense you will have to put up with.
This happens regularly in the SFBA, in Marin County. Every rainy season I see at least one house being built through Nov-Dec-Jan that is in the bare studs stage and gets soaked with a week or so of constant rain.
And then the sun comes out and they immediately tyvek wrap and seal the whole house up. Sopping wet, soaked studs, entrapped on both sides. I would love to open up the drywall in one of those two years later and see what the inside of the walls look like...
These are very expensive homes ... the four I am thinking of over the past two years were all 2M+.
This talk really gave me a foundation for understanding how moisture works in a building enclosure through seasons: https://www.youtube.com/watch?v=Ld8pzIu45F8
The speaker is a little hammy, but he's doing (more or less) legitimate science, and he laid out a bunch of principles I didn't understand before.
In particular, the different layers of the wall (ballistic, water, insulation, vapor, structure) really need to go in the right order, and at literally every exterior joint in the house you need to match up all five layers. There are also several layers that it is crucial to vent/drain.
It's extremely complicated, and for the most part just obeying code and convention will only get you 80% of the way there.
It seems to me there are also anti-patterns ensconced in code and convention. The idea that insulation goes inside the structural layer for example. You want your insulation layer to be unbroken.
I know they're in the desert, but drywall really should happen after the building envelope is sealed.
It's why bad actors (such as the ones described above) keep getting away with what they do.
Entering a rainy season without a roof being sheathed is also bad contracting.
How does that work?
You may not be eligible for regular tenant protections, but you're still eligible for recourse through regular courts, no?
My first rental in London had bad mould problems. The landlord refused to fix them. We ended up with dehumidifiers throughout the house to keep it under control. When we left after a year, he complained at us for keeping dehumidifiers around when potential tenants came to visit - it raised too many questions! This was a 2200+/mo rental that he had bought for about 100k 15 years ago. What a crook.
For an air purifier, you need one with a UV light.
1. Air filters might reduce the airborne spores, but if you have mold already growing behind some wardrobe you are wasting time.
2. Hydrogen peroxide, chloride, and isopropyl alcohol are all good tools to fight it when you find a place where it grows, but ultimately you have to solve the problem at a deeper level as mold has excellent survival skills (you might clean the wall but the spores in the air infect it again right afterward).
3. In order to eliminate mold, you have to change the environmental conditions. As most living organisms mold requires food and water. The water comes either from inside the wall (that is something only your landlord can fix) or from the air. So try to maintain a low humidity level within your apartment (<50% should be okay). The easiest way to achieve that is by using your heating and replacing all air within your apartment by opening all windows for 5 minutes (to let in cold air, no longer, as it will cool down the temperature of the wall otherwise), three times a day. Mold nourishes itself from organic material. Very often that means fabric, wood or wallpapers (yes removing your wallpaper might be a good idea). Since water condenses in cold spots first, those are the place you want to keep looking for (walls next to windows, corners of a room).
Three years ago I had a mold problem in my apartment. Following the above advice, the mold didn't come back (except for a few spots in the shower, but that is kinda difficult to keep dry).
If you smell "swimming pool" where no pool exists, it might be prudent to leave the area immediately and take a 1000 mg vitamin C tablet, before making any attempts to discover the source of the smell. (Taking vitamin C after the damage is already done won't help.) If the odor is especially strong, or if it causes any irritation to your nose and eyes, evacuate, and do not return. Call your emergency services number and tell them you smelled a strong chlorine odor.
Don't combine bleach cleaners with ammonia cleaners, ever. Don't even store them in the same place. Also avoid mixing bleach with acids, such as vinegar.
Any advice appreciated.
The mould is still there but the dry air stops it from growing and sporing which is what makes you stick. If humidity creeps up the mould will grow again. Be aware that mould is virtually everywhere and is only harmful if there is enough of it around sporing or if you touch it.
The problem is, once the calcium chloride has absorbed the moisture from the air and is saturated, you have to take it out and dry it to make it effective again. That might be cheaper (in terms of energy) than refrigerant phase-change dehumidification, but it's a lot more labor intensive.
Natural airflow with the outside at 90% relative humidity isn’t going to do a thing other than make the interior occupants ornery.
The natural airflow design of Apple Park for example, that works incredibly well, but that same design in Houston or New Orleans would be catastrophically ridiculous.
https://www.cdc.gov/mold/stachy.htm
I'm not really sure about keeping the humidity below 50% though. The UK and most of Northern Europe has rather high humidity in the winter. It commonly reaches 80-90 RH outside, so you'd have to heat your house to 25c/77F to bring the humidity below 50%.
Indoors? No, not at all. In the winter the temperature in my house/office is 21-22C and 17 at the lowest at night, and I have to run a humidifier 24/7 to keep the humidity over 30% (otherwise the wooding floors shrink too much).
Currently in the bedroom (thanks Netatmo) it's 17.8° and 69% humidity (with one of the three windows open about 0.5"). That compares to 14.0° and 78% on the balcony. Looking at the graphs, 50% is the lowest indoor humidity over the last month.
Still - mold in houses is not a problem in houses in Western/Northern Europe, except for the most pathological cases (for example, mold scores you iirc 2 points in Belgium on the 'uninhabitable property' test, where 9 gets your building declared unfit for living in. Having small holes in the roof or small cracks in the walls (still structural defects) gets you 3. That's how unusual mold is around here. OTOH when I lived in New Zealand, mold was met with 'eh, there's bleach in isle 5 at Countdown, just wipe it down.'. I was like 'wut?'.
Alas, it does not, but that's possibly because other windows are open around the place and there's relatively good airflow.
> I'm going to try this same experiment tomorrow, I'm quite interested to know.
I'll see how it goes tomorrow with the window closed and various doors closed to minimise the effect of the other windows.
[0] https://en.wikipedia.org/wiki/File:Relative_Humidity.png
When it gets to the cold part of winter it's obviously easier, but this time of year it's hard to get it below 50% RH inside just by controlling the temperature.
Cold air can simply hold less water overall, at 20C it can easily hold double as much water as it can at 0C.
There being a pressure difference is nonsense, you can get the same air pressure in the winter as in summer (though it tends to go on the Low side more often). What you probably mean is the vapor pressure, ie the natural pressure the liquid wants to be at in a closed container, though while it is largely depdenent on temperature, it does so in a linear/positive way, so at lower temperature, water will evaporate less (otherwise ice would more easily sublimate).
Once you go below zero a water content of a few grams can easily hit 100% RH which would barely manage 5% or less at 30C.
If you can blow dry air over its surface, you can evaporate liquid water (or sublimate water ice) even when the relative humidity is 100%.
You can think of air as a gaseous solution, and its water vapor content like table salt in aqueous solution. Temperature affects the solubility, and if the solution is saturated, no more can dissolve. You can still dissolve salt crystals sitting in a saturated cold saltwater solution by squirting warm freshwater onto the bottom of the container. If that then mixes with the rest of the solution, and everything cools down again, that dissolved salt can then precipitate out somewhere else (like rain), or form a suspension of tiny crystals (like fog or clouds).
The solubility of H2O vapor in atmospheric gas increases with temperature. But you can also do something with a gaseous solvent that you can't easily do with a liquid solvent, which is to change the pressure. Higher pressure lowers the solubility of water in air, but to a far lesser extent than a decrease in temperature. Even though the vapor pressure is dependent only on temperature, evaporation occurs whenever the vapor pressure exceeds the partial pressure of H2O at the interface. Increasing the overall air pressure also increases the partial pressure of H2O vapor by a proportional amount, so inhibits further evaporation. But water vapor is also less dense than N2, O2, and most other atmospheric gases, so the means of measuring pressures gets complicated.
When you involve wind, and stratified airflows, it gets even more complicated. The air blowing across water or water ice could have been previously warmed by the ground just enough to evaporate more water, then get pushed higher by an angled snowbank into colder, saturated air, and it will then dump the excess water as small ice crystals. A solid block of ice can then become "rotten" as a snowdrift forms downwind of it. The overall average temperature may say that ice should stay frozen, but the wind can still carry a tiny bit of water vapor at a time, thanks to local fluctuations, and with enough volume of air to move it, that ice will drift.
This might or might not have been feasible given OP's budget, heating arrangements, and general preference. I for one would not want to live in such a hot room for a whole season even if I could afford to. I keep my room cooler than that even in the summer!
Sorry to ask, but I’m not really sure I got it right: Do you think the DIY air purifier was the cause of these health problems? Or did it at least contribute by letting the mold come back (inside)?
As others have noted, a dehumidifier could help. But what prevents mold from growing inside these dehumidifiers as well? Sure, they’re mainly built from plastic and metal, so no paper as in your case. Will that be enough to prevent mold (or bacteria)?
Otherwise, a dehumidifier could turn into yet another health hazard over time.
I briefly lived inside an apartment that was previously a cave. There was a plaster wall separating from the outside, and after raining, it ended up covered in mold. We cleaned it with bleach, but moved out soon after. I hope I did not get too much exposure.
Do not forget that black mold release mycotoxins, which are carcinogenic.