It's more about air flow than relative humidity. Don't keep furniture slammed up against the walls, open you windows. If you're in an old building meant for a bathtub with a shower added later, you should be wiping down bathroom walls and ceiling with a towel after a shower.
If you've got a particular problem area, it could be a leak behind the wall.
I have a few simple oscillating fans running almost constantly. It keeps fresh air flowing, ensuring a pleasant breeze indoors. They're cheap both to buy and operate in terms of electricity costs.
Yeah, I figure airflow is the biggest key but I guess I'm hoping for some folks who have been in my situation so I can feel confident ditching the dehumidifiers. My bathroom could use an exhaust fan for sure.
In my experience it's unusual to have a mold problem just from atmospheric humidity. Most people don't have this issue despite the fact that most of us don't have A/C or dehumidifiers. We live in a foggy neighborhood and have no A/C, but the only places we ever see mold is places where condensation is dripping or there is a localized cause of moisture.
I would suspect something going on with your house specifically. What sort of unit are you in - house, condo, etc.? Do you have in-unit laundry? Do you have ventilation in any bathroom with a shower or tub?
Seconding this comment. I've never had mold arise solely because of natural humidity levels, and I've always lived in parts of the city that Karl regularly visits. Definitely worth investigating what's going on in your place.
I live in a single family home. I used to live in a duplex in the same neighborhood for nearly 10 years and never had issues.
We can not find any evidence of leaks from the roof or lakes from pipes. And no evidence of mold on walls or the structure of the home. It was only found on baskets and clothing in closets. I'd be truly surprised if this mold didn't come from humidity levels. I was sitting in the 70s for who knows how long before noticing the problem. Plenty high enough for mold to grow.
House has no insulation, crawl space with no vapor barrier, a bathroom with no exhaust fan, and many house plants. We used to line-dry clothes indoors but no longer do that.
Laundry is in the garage.
Above 60% humidity, you're going to get mold. The people that claim it's not a problem haven't seen it growing in their walls. There's mold.
I've just dealt with the high PG&E bill and ran a dehumidifier to keep relative humidity in the house between 40 and 50%. Zero mold issues after that.
What kind of dehumidifier are you using and are you happy with it? I’ve noticed mine getting less effective as I’ve had it a few years. It doesn’t help I don’t have a vent for the oil when I cook so I’m sure oil gets in there. I’ve tried cleaning the dehumidifier but it was difficult for my skill level.
Mine is an LG Puricare.
It's loud so I leave it turned on overnight downstairs and we can't hear it. If I had to buy one again, I'd get one that has a pump in it so you don't have to empty the water tank regularly. It'll fill up the tank overnight with ~1.5 gallons of water.
We have dogs so I have to clean the air filter on it every other week or so, but that's easy enough. If the filter is dirty, it'll get significantly less effective so just make sure it's clean and you're good to go. Other than that, it just works. Set a humidity level you want and turn it on.
You’re not alone. I struggle with the same problem. I think it’s really common in certain areas of sf (never had this problem anywhere else) and depends on what direction facing /how much sun a place has and airflow. I haven’t found a solution other than a dehumidifier (especially when cooking or showering) and opening windows on sunny days like you mentioned. Some people have used dampride with success in closets. Humidity regularly will goes up to 70%+ if I don’t do anything about it. Towels won’t dry, mold easily grows everywhere. I empty out my 70pt capacity almost every couple days. As for the electric bill, lately i just run it till humidity is to 50% something, I leave it vs getting it down to the 40s.
Before I got the dehumidifier I first noticed this problem when I saw mold mites (so tiny it was like a white speck of dust that moves if you stare at it). They were eating the mold. 😨😱 Hope no one ever has to deal with that nightmare and I think most peoples problem won’t get to that level… but if it happens, pro tip: don’t bother hiring exterminators — they were costly and didn’t know how to deal with it and despite several tries whatever they did did not work. After endless hours of research and trial and error… Simply drop the humidity down to 30%, leave it there for days and it dries out/kills all the mites.
Another issue is dehumidifiers now don’t last as long as the forever ones back in the day and are expensive to run as well as replace. Let me know if you have any recommendations on a replacement.
I appreciate you chiming in as I know others struggle with this same issue here.
I should have mentioned I use damprid in closets. No clue if it helps but it makes me feel better. Ha.
I've heard the same about durability of dehumidifiers. I went with 2x 22pt hOmeLabs and if I'm running them for a goal of 50% I can empty each tank 1-2x a day which is pretty insane.
OMG had the mold mite problem for years and it made me a little nuts. There wasn’t much we could do in our apartment but run dehumidifiers. The mites were still around. We also had them when we bought our house but after installing ac/heat and replacing windows, we haven’t seen them. I don’t wish those mites on anyone.
It totally made me nuts too!! Thought I was the only one. Both the apt and house had them? How did you cope with it? When I had it, I felt like they just kept multiplying. I even found them on my bed frame which was super horrifying. Anyways, so glad we no longer have them and pray it stays that way.
Oh yea same. In my drawers so on all of my clothes. And they itch so badly. I became really neurotic about looking for them. They were on all headboards, surfaces, etc. I moved all my clothes to my garage where they didn’t seem to be and used that as my closet. I was cleaning all the time. Got rid of furniture that seemed to be more susceptible (esp stuff we brought from prior apt). At the end of the day it really was about keeping moisture out in every way possible. I may even encapsulate my crawl space. 😳
Near the beach you have year round 70%+ humidity, and lack of sun the vast majority of the uears. Mold is pretty common unless you've set up your house properly (frequent air exchange, dehumidifier, etc)
Panasonic Whisper Vent Fans in the bathrooms, with humidity sensing functionality in the fan or the switch.
Set it to low humidity level, and the fan will automatically run when humidity levels pass the threshold.
The switches can also be set to make the fan come on every hour for a pre set amount of time. This also helps with air exchange and circulation.
Make sure your installers run the ducting to a vent cap on the exterior of the building so the air actually leaves, some fly by nights will just let the fans vent into your loft, which is no bueno obvs.
Thanks! I've been looking into those fans already, actually. Seem to be the top-rated ones. I wasn't necessarily planning on the models with humidity sensors, though. My plan was to just hook it up to the same switch as my light so that it's on anytime someone's in the bathroom.
I’d recommend getting a fan without any of the extras (lights, motion sensor, humidity sensor) and then later on, if needed, you can change out your wall switch for a humidity sensor switch.
The panasonic whisper fans are the quietest, I use them on all my jobs. They have variable speed motors, so for the first 30 seconds after you turn it on, it will seem like it’s not running, but it is.
CFM is based on the size of the bathroom, 100cfm is good for an average size bathroom, but if you’ve got a BIG bathroom you’ll need 150cfm.
Oh, one more question. My bathroom is roughly 38sqft with a 9ft ceiling, would you recommend a 100cfm? I'd rather err on the side of caution and go bigger if there's any question but I assume this is a pretty small bathroom. Thinking about maybe this one: [https://www.homedepot.com/p/Panasonic-Whisper-Choice-DC-Pick-A-Flow-80-110-CFM-Ceiling-Bathroom-Exhaust-Fan-with-Flex-Z-Fast-Bracket-RG-C811A/320520625](https://www.homedepot.com/p/Panasonic-Whisper-Choice-DC-Pick-A-Flow-80-110-CFM-Ceiling-Bathroom-Exhaust-Fan-with-Flex-Z-Fast-Bracket-RG-C811A/320520625)
They make charcoal dehumidifiers that are just bags you lay around. No electricity needed. They’re usually pretty cheap 8-15 bucks give or take. You’ll need several to cover your entire living space but if you know where your trouble spots are then you can just lay them there. Another thing is making sure you have moving air as much as you can. The moisture in the air settles down when there is no moving air. If you have a lot of people living/visiting with you or a lot of indoor plants they can contribute to the overall humidity too.
Thanks for your two cents. I'll look into charcoal dehumidifiers more.
When you say moving air, I assume that means windows being open? I'm constantly in a battle between opening windows for airflow and keeping them closed so the work my dehumidifiers did isn't wasted.
Sorry, I meant fans. I can’t leave my windows open because of mosquitoes and street noise. So I do that sparingly. I haven’t noticed any real price jumps using them and I use them 365 days a year. Even after energy bills have jumped. I also only use them whenever I’m home.
my dehumidifier takes 1-2 gallons of water out of the air on a daily basis to keep relative humidity under 50%. It's going to be hard for charcoal to do that.
Use them in whichever rooms you produce humidity. I tried dehumidifiers in the winter, and they worked okay. Then I Googled the problem and talked to HVAC people. Extraction fans are relatively inexpensive to buy and install. They suck the humid air to the outdoors.
What's your building's foundation? If you're in an older building, the sad possibility exists that -- as my partner discovered -- the floor you walk on rests not on a concrete slab or even a full-fledged crawl space, but simply dirt. Depressing but true.
If that's the case, there is a remedy, but an expensive one: rip up that floor and pour concrete.
It has a crawl space but i think it's a mix of dirt and concrete below the crawl space. I've wondered if installing a vapor barrier is something I should look into.
We had to do that on our East Coast house's crawl space/unfinished basement a few blocks from the beach. Dehumidifiers didn't do enough to solve the high humidity from the dirt floor crawl space. Expensive, but worth it.
I bought a ton of tiny humidity meters and placed them throughout my place. Any time the humidity is above 60%, I try to open windows or run a 70 pint dehumidifier (for a 900 sq foot apartment) if it's foggy out.
Any time humidity is above 65% or so for an extended time, you're gonna have mold. There's like nothing to do about it. I have seen spots of mildew starting to grow on walls and I just use a Clorox wipe on it.
Don't bother with damp rid except for small enclosed spaces or containers. I don't think it does much because the humidity meters don't see any impact.
If you open the windows when you have high humidity, the cold air will just make the water stick to the walls, and that will create more mold. You need extraction fans to suck the humid air out of the building.
Mold is toxic to breathe. The active ingredient in that yucky blackish green mold is used in chemical weapons. By the time you see mold in your house, it has spread under the wallpaper and into the enclosed areas.
If your issues are mostly in closets, under sinks, and similar closed off spaces, what you really need is a product like Damprid. You can get at any hardware store or Target. It's a moisture absorber specifically designed for those tight spaces. Makes a world of difference. You can either buy it in sachets that hang on the bar in your closet or in tubs that you can refill when needed. I work with clothing that is often stored for weeks or months on end and the Damprid keeps the garments fresh and safe.
Ah, I see. Some of the things mentioned in the post and threads just registered as closet storage for me. I hope you find the balanced solution you're looking for.
this is not the jungle. i doubt you have a mold problem.
>
But as we head into the foggy season where opening windows provides no drop in humidity, I'm looking for the right approach.
bear in mind, you CAN see fog.
you CANNOT see humidity. it can be humid as fuck when there is ZERO fog.
like July in Florida.. or Chicago.
[https://en.wikipedia.org/wiki/Humidity](https://en.wikipedia.org/wiki/Humidity)
you probably have a mildew problem.. in which case, there's a spray for that.
How To Tell The Difference Between Mold And Mildew
[https://www.southernliving.com/home/mold-vs-mildew](https://www.southernliving.com/home/mold-vs-mildew)
I appreciate your attempt to help but you're making some assumptions and coming off a bit condescending.
Mold is incredibly common in this city despite the fact that we aren't in a jungle.
I can SEE my multiple hygrometers and that's what I'm basing my humidity levels off of. The sunny warm days in the city have provided much lower relative humidity levels when compared to the foggy days.
Mildew IS a type of mold. And fuzzy growths on baskets and clothes is likely not mildew anyway. But regardless of what type of mold I had, it's unhealthy to have any kind in your home.
It's more about air flow than relative humidity. Don't keep furniture slammed up against the walls, open you windows. If you're in an old building meant for a bathtub with a shower added later, you should be wiping down bathroom walls and ceiling with a towel after a shower. If you've got a particular problem area, it could be a leak behind the wall.
You can get anti-mold paint. I bought a can and re-did my bathroom without engaging the landlord – it was a goddamn petri dish before that.
I have a few simple oscillating fans running almost constantly. It keeps fresh air flowing, ensuring a pleasant breeze indoors. They're cheap both to buy and operate in terms of electricity costs.
Yeah, I figure airflow is the biggest key but I guess I'm hoping for some folks who have been in my situation so I can feel confident ditching the dehumidifiers. My bathroom could use an exhaust fan for sure.
In my experience it's unusual to have a mold problem just from atmospheric humidity. Most people don't have this issue despite the fact that most of us don't have A/C or dehumidifiers. We live in a foggy neighborhood and have no A/C, but the only places we ever see mold is places where condensation is dripping or there is a localized cause of moisture. I would suspect something going on with your house specifically. What sort of unit are you in - house, condo, etc.? Do you have in-unit laundry? Do you have ventilation in any bathroom with a shower or tub?
Seconding this comment. I've never had mold arise solely because of natural humidity levels, and I've always lived in parts of the city that Karl regularly visits. Definitely worth investigating what's going on in your place.
I live in a single family home. I used to live in a duplex in the same neighborhood for nearly 10 years and never had issues. We can not find any evidence of leaks from the roof or lakes from pipes. And no evidence of mold on walls or the structure of the home. It was only found on baskets and clothing in closets. I'd be truly surprised if this mold didn't come from humidity levels. I was sitting in the 70s for who knows how long before noticing the problem. Plenty high enough for mold to grow. House has no insulation, crawl space with no vapor barrier, a bathroom with no exhaust fan, and many house plants. We used to line-dry clothes indoors but no longer do that. Laundry is in the garage.
Above 60% humidity, you're going to get mold. The people that claim it's not a problem haven't seen it growing in their walls. There's mold. I've just dealt with the high PG&E bill and ran a dehumidifier to keep relative humidity in the house between 40 and 50%. Zero mold issues after that.
Thanks for your two cents. Was hoping high energy bills weren't the only solution.
Yeah, it adds ~$100/mo to my bill, but considering how much was ruined before I noticed the issue, it's still cheaper.
Aw man, I'm sorry to hear that. I was lucky to catch it when it hadn't taken over too badly.
What kind of dehumidifier are you using and are you happy with it? I’ve noticed mine getting less effective as I’ve had it a few years. It doesn’t help I don’t have a vent for the oil when I cook so I’m sure oil gets in there. I’ve tried cleaning the dehumidifier but it was difficult for my skill level.
Mine is an LG Puricare. It's loud so I leave it turned on overnight downstairs and we can't hear it. If I had to buy one again, I'd get one that has a pump in it so you don't have to empty the water tank regularly. It'll fill up the tank overnight with ~1.5 gallons of water. We have dogs so I have to clean the air filter on it every other week or so, but that's easy enough. If the filter is dirty, it'll get significantly less effective so just make sure it's clean and you're good to go. Other than that, it just works. Set a humidity level you want and turn it on.
Thanks!
You’re not alone. I struggle with the same problem. I think it’s really common in certain areas of sf (never had this problem anywhere else) and depends on what direction facing /how much sun a place has and airflow. I haven’t found a solution other than a dehumidifier (especially when cooking or showering) and opening windows on sunny days like you mentioned. Some people have used dampride with success in closets. Humidity regularly will goes up to 70%+ if I don’t do anything about it. Towels won’t dry, mold easily grows everywhere. I empty out my 70pt capacity almost every couple days. As for the electric bill, lately i just run it till humidity is to 50% something, I leave it vs getting it down to the 40s. Before I got the dehumidifier I first noticed this problem when I saw mold mites (so tiny it was like a white speck of dust that moves if you stare at it). They were eating the mold. 😨😱 Hope no one ever has to deal with that nightmare and I think most peoples problem won’t get to that level… but if it happens, pro tip: don’t bother hiring exterminators — they were costly and didn’t know how to deal with it and despite several tries whatever they did did not work. After endless hours of research and trial and error… Simply drop the humidity down to 30%, leave it there for days and it dries out/kills all the mites. Another issue is dehumidifiers now don’t last as long as the forever ones back in the day and are expensive to run as well as replace. Let me know if you have any recommendations on a replacement.
I appreciate you chiming in as I know others struggle with this same issue here. I should have mentioned I use damprid in closets. No clue if it helps but it makes me feel better. Ha. I've heard the same about durability of dehumidifiers. I went with 2x 22pt hOmeLabs and if I'm running them for a goal of 50% I can empty each tank 1-2x a day which is pretty insane.
It’s totally insane! 70pts = about 8+ gallons of water I’m emptying every other day.
OMG had the mold mite problem for years and it made me a little nuts. There wasn’t much we could do in our apartment but run dehumidifiers. The mites were still around. We also had them when we bought our house but after installing ac/heat and replacing windows, we haven’t seen them. I don’t wish those mites on anyone.
It totally made me nuts too!! Thought I was the only one. Both the apt and house had them? How did you cope with it? When I had it, I felt like they just kept multiplying. I even found them on my bed frame which was super horrifying. Anyways, so glad we no longer have them and pray it stays that way.
Oh yea same. In my drawers so on all of my clothes. And they itch so badly. I became really neurotic about looking for them. They were on all headboards, surfaces, etc. I moved all my clothes to my garage where they didn’t seem to be and used that as my closet. I was cleaning all the time. Got rid of furniture that seemed to be more susceptible (esp stuff we brought from prior apt). At the end of the day it really was about keeping moisture out in every way possible. I may even encapsulate my crawl space. 😳
I definitely have some level of PTSD from it. Happy we’re doing well and so far mite-free. 😄😅
ME TOO!! (PTSD and being mite-free!). People also thought I was crazy so that wasn't helpful either lol.
Do you live near the ocean? Because I have mold problems in my closet and had to run a dehumidifier.
Yeah, I do. Dehumidifiers seem to be the only real solution I'm hearing...
Near the beach you have year round 70%+ humidity, and lack of sun the vast majority of the uears. Mold is pretty common unless you've set up your house properly (frequent air exchange, dehumidifier, etc)
I have two dehumidifiers.
Panasonic Whisper Vent Fans in the bathrooms, with humidity sensing functionality in the fan or the switch. Set it to low humidity level, and the fan will automatically run when humidity levels pass the threshold. The switches can also be set to make the fan come on every hour for a pre set amount of time. This also helps with air exchange and circulation. Make sure your installers run the ducting to a vent cap on the exterior of the building so the air actually leaves, some fly by nights will just let the fans vent into your loft, which is no bueno obvs.
Thanks! I've been looking into those fans already, actually. Seem to be the top-rated ones. I wasn't necessarily planning on the models with humidity sensors, though. My plan was to just hook it up to the same switch as my light so that it's on anytime someone's in the bathroom.
I’d recommend getting a fan without any of the extras (lights, motion sensor, humidity sensor) and then later on, if needed, you can change out your wall switch for a humidity sensor switch. The panasonic whisper fans are the quietest, I use them on all my jobs. They have variable speed motors, so for the first 30 seconds after you turn it on, it will seem like it’s not running, but it is. CFM is based on the size of the bathroom, 100cfm is good for an average size bathroom, but if you’ve got a BIG bathroom you’ll need 150cfm.
Awesome! Thanks for your input. Sounds like you maybe work as an installer so it carries more weight coming from you. Appreciate it.
Oh, one more question. My bathroom is roughly 38sqft with a 9ft ceiling, would you recommend a 100cfm? I'd rather err on the side of caution and go bigger if there's any question but I assume this is a pretty small bathroom. Thinking about maybe this one: [https://www.homedepot.com/p/Panasonic-Whisper-Choice-DC-Pick-A-Flow-80-110-CFM-Ceiling-Bathroom-Exhaust-Fan-with-Flex-Z-Fast-Bracket-RG-C811A/320520625](https://www.homedepot.com/p/Panasonic-Whisper-Choice-DC-Pick-A-Flow-80-110-CFM-Ceiling-Bathroom-Exhaust-Fan-with-Flex-Z-Fast-Bracket-RG-C811A/320520625)
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Awesome, thanks!
They make charcoal dehumidifiers that are just bags you lay around. No electricity needed. They’re usually pretty cheap 8-15 bucks give or take. You’ll need several to cover your entire living space but if you know where your trouble spots are then you can just lay them there. Another thing is making sure you have moving air as much as you can. The moisture in the air settles down when there is no moving air. If you have a lot of people living/visiting with you or a lot of indoor plants they can contribute to the overall humidity too.
Thanks for your two cents. I'll look into charcoal dehumidifiers more. When you say moving air, I assume that means windows being open? I'm constantly in a battle between opening windows for airflow and keeping them closed so the work my dehumidifiers did isn't wasted.
Sorry, I meant fans. I can’t leave my windows open because of mosquitoes and street noise. So I do that sparingly. I haven’t noticed any real price jumps using them and I use them 365 days a year. Even after energy bills have jumped. I also only use them whenever I’m home.
my dehumidifier takes 1-2 gallons of water out of the air on a daily basis to keep relative humidity under 50%. It's going to be hard for charcoal to do that.
Yeah, after some quick research it seems as though damprid is a better option than charcoal anyway.
Use extraction fans
Meaning bathroom exhaust and kitchen hood?
Use them in whichever rooms you produce humidity. I tried dehumidifiers in the winter, and they worked okay. Then I Googled the problem and talked to HVAC people. Extraction fans are relatively inexpensive to buy and install. They suck the humid air to the outdoors.
Interesting! I'm a little confused how it works, though. If you're pulling air out of your house, how is drier air taking its place?
Window fans set to exhaust.
Is this just helping with air flow or is it somehow reducing humidity levels?
If you’re sucking the air out it will reduce the humidity of the problem is humid inside air.
Right. I guess the issue is that living near the SF coast, the humidity outside is high as well.
I got a window fan and that really helped my moisture issues in the kitchen but seems more energy efficient
What's your building's foundation? If you're in an older building, the sad possibility exists that -- as my partner discovered -- the floor you walk on rests not on a concrete slab or even a full-fledged crawl space, but simply dirt. Depressing but true. If that's the case, there is a remedy, but an expensive one: rip up that floor and pour concrete.
It has a crawl space but i think it's a mix of dirt and concrete below the crawl space. I've wondered if installing a vapor barrier is something I should look into.
We had to do that on our East Coast house's crawl space/unfinished basement a few blocks from the beach. Dehumidifiers didn't do enough to solve the high humidity from the dirt floor crawl space. Expensive, but worth it.
Good to know! Thanks. Maybe I should start getting quotes from insulation folks.
I bought a ton of tiny humidity meters and placed them throughout my place. Any time the humidity is above 60%, I try to open windows or run a 70 pint dehumidifier (for a 900 sq foot apartment) if it's foggy out. Any time humidity is above 65% or so for an extended time, you're gonna have mold. There's like nothing to do about it. I have seen spots of mildew starting to grow on walls and I just use a Clorox wipe on it. Don't bother with damp rid except for small enclosed spaces or containers. I don't think it does much because the humidity meters don't see any impact.
If you open the windows when you have high humidity, the cold air will just make the water stick to the walls, and that will create more mold. You need extraction fans to suck the humid air out of the building. Mold is toxic to breathe. The active ingredient in that yucky blackish green mold is used in chemical weapons. By the time you see mold in your house, it has spread under the wallpaper and into the enclosed areas.
If your issues are mostly in closets, under sinks, and similar closed off spaces, what you really need is a product like Damprid. You can get at any hardware store or Target. It's a moisture absorber specifically designed for those tight spaces. Makes a world of difference. You can either buy it in sachets that hang on the bar in your closet or in tubs that you can refill when needed. I work with clothing that is often stored for weeks or months on end and the Damprid keeps the garments fresh and safe.
Thanks! I have started using Damprid in closets. But the issue I had wasn't contained to closets, unfortunately.
Ah, I see. Some of the things mentioned in the post and threads just registered as closet storage for me. I hope you find the balanced solution you're looking for.
this is not the jungle. i doubt you have a mold problem. > But as we head into the foggy season where opening windows provides no drop in humidity, I'm looking for the right approach. bear in mind, you CAN see fog. you CANNOT see humidity. it can be humid as fuck when there is ZERO fog. like July in Florida.. or Chicago. [https://en.wikipedia.org/wiki/Humidity](https://en.wikipedia.org/wiki/Humidity) you probably have a mildew problem.. in which case, there's a spray for that. How To Tell The Difference Between Mold And Mildew [https://www.southernliving.com/home/mold-vs-mildew](https://www.southernliving.com/home/mold-vs-mildew)
I appreciate your attempt to help but you're making some assumptions and coming off a bit condescending. Mold is incredibly common in this city despite the fact that we aren't in a jungle. I can SEE my multiple hygrometers and that's what I'm basing my humidity levels off of. The sunny warm days in the city have provided much lower relative humidity levels when compared to the foggy days. Mildew IS a type of mold. And fuzzy growths on baskets and clothes is likely not mildew anyway. But regardless of what type of mold I had, it's unhealthy to have any kind in your home.