Last weekend, I popped open my mini warehouse only to discover one of a car owner’s worst nightmares. One of my favorite cars, my 2008 Saturn Sky Red Line, had a seat with rapidly spreading mold. Sadly, this isn’t even the first time this has happened to me, but it’s now the fourth time. I’m tired of cleaning out mold, and now I’m wondering: How do I stop this from happening again?
If you’re a longtime reader, you may remember that, in 2022, I wrote a story about how my 2005 Smart Fortwo became filled with what I called “forbidden polka dots.” Right before I stored the car for the winter in 2021, I had an accident with a car cover that let about a gallon of water into the interior. I forgot to fully dry out the car before parking it, and my reward the next spring was a car that was full of mold.
My wife cleaned out the car, and it has been fine ever since. The mold has not come back. I haven’t even smelled the telltale scent of mold, either. Since then, I also haven’t had a problem with any of my other cars. I’d pop open my mini warehouse, drive away in whatever chariot I chose, and life would be good.
Something different must have happened this year, because it feels like I’ve been fighting a losing battle with mold this summer. I have found a grand total of three more of my cars with the stuff in them. I’m not exactly sure what’s going on, and I’m not entirely sure how to stop it.
Mold Is Nasty Stuff
Back in 2022, when I had the mold issue in my 2005 Smart Fortwo, there was an easy explanation: I was a goofball and stored a car with a gallon of water hiding under its carpet – a mold farm, basically.
The United States Environmental Protection Agency has a pretty good primer on mold:
Molds are a natural part of the environment and can be found almost anywhere that moisture and oxygen are present. They belong to the kingdom Fungi and live in moist places such as soil, plants and dead or decaying matter. Outdoors, molds play a part in nature by breaking down dead organic matter such as fallen leaves, dead trees and other debris; however, indoors mold growth should be avoided.
There are many types of mold – all of them need water or moisture to grow. When excessive moisture accumulates in buildings or on building materials, mold growth often occurs, particularly if the moisture problem remains undiscovered or unaddressed.
Molds spread by producing tiny reproductive cells called spores that waft through the air. Mold spores usually cannot be seen without magnification (ranging in size from 2-10 um) and are naturally present in both indoor and outdoor air. Some molds have spores that are easily disturbed and settle repeatedly with each disturbance. Other molds have sticky spores that will cling to surfaces and are dislodged by brushing against them or by other direct contact. Spores may remain able to grow for years after they are produced. In addition, whether or not the spores are alive, the allergens in and on them may remain allergenic for years.
Yeah, mold is the stuff of nightmares. It’s also really bad for you, and can cause Asthma attacks, headaches, and, depending on how your body reacts to its environment, more serious issues.
Generally, mold requires four factors to grow: moisture, oxygen, a temperature between 40 degrees and 100 degrees, and a food source that contains cellulose. Mold will happily grow on walls, fabric, wood, leather – even paper, if you let it. Also, a quirk about mold is that simply exposing the mold to a temperature extreme might not be enough to kill it. Mold may go dormant in freezing or hot temperatures, but it is unlikely to die based on a temperature swing alone. Once conditions permit growth again, the mold will just kick back into action.
My Storage Situation
My mini warehouse is an interesting place. It sits maybe 500 feet from a lake and is more or less situated right in the middle of a chain of lakes. The area around my unit gets seriously humid. My warehouse also isn’t like a pole barn; the structure and floor of the building are concrete, and the roof appears to be not much different than what you’d find on top of an older commercial building. This is all to say that, based on the water stains on the ceiling in the building, this roof has leaked in the past. Likewise, the building gets extremely humid, just like the outside. So, at minimum, there’s a lot of water in the air. Also, spiders love this place, so I got that goin’ for me.
Here’s how Sheryl beat the crap out of the mold in my 2005 Smart:
Sheryl’s plan involves multiple prongs. The first involves this Bissell Little Green Pro cleaning machine. It injects searing hot water (or a chemical mix) into the surface that you’re cleaning and uses both brushing action and vacuum to get the job done. She combined it with RMR-86 Pro mold remover. The jug of RMR contains one of the active chemicals of bleach, among other harsh stuff.
Sheryl made somewhat short work of the mold on the passenger seat. It took several passes and lots of scrubbing, but it took give or take an hour for her to be satisfied with the job.
[…]
Next came the driver seat, and she said that the growth on it was much worse. The seat bottom in particular required a lot of scrubbing to get through. However, after about two hours even it, too, looked extremely clean.
As I noted earlier, the mold hasn’t been back! So, this process worked out. I actually had doubts about this. It seems a lot of folks go hard on mold remediation, and remove their seats, dashboard, interior panels, and carpet to give them a ridiculously deep cleaning. Some folks straight up throw some of those parts away. Perhaps my car wasn’t bad enough to warrant tearing down the whole interior.
Here We Go Again
I figure the humidity supercharged the mold growth in that Smart. But I’m not entirely sure what happened this year with my other cars sprouting mold. Back in the spring, I excitedly attempted to drive my Honda Beat before finding its steering wheel covered in the fungi that are not fun guys. I cleaned up the mold with more of that RMR-86 stuff, monitored it for a while, and then sold the car.
Then, last week, I opened my unit hoping to drive my Saturn Sky Red Line, and was stopped hard by this sight:
Crap.
This sent me into a panic, and I decided to check every other car in the unit. The 2006 Volkswagen Touareg V10 TDI was fine, as was the 2016 Smart Fortwo Edition #1, the 1997 Honda Life, and the 1989 Suzuki Every. All of the motorcycles were good, too. The only other troublemaker was the 2006 Smart Fortwo CDI, which had one little moldy dot on its driver seat.
I didn’t get it. I stored these cars with completely dry interiors with their windows rolled up. Mold has no reason to attack my beloved Saturn! Then, I started to think about it. Remember when I said mold needs moisture, oxygen, 40 – 100 degrees, and a cellulose food source? While the interiors of my cars might not be wet, there’s a ton of moisture in the air – enough for mold to take hold.
I did some digging and found out I’m not the only one suffering with the stuff. People who park their cars inside barns sometimes find mold in them after just one season, even though the car was totally dry when it went into the barn. The issue is made even worse when the barn has an imperfect roof. That was the case in the story told by Rob Siegel of BimmerLife. Rob, like me, stores a lot of cars and tries to pay as little as possible for storage. In 2023, he ran into his own mold nightmare.
Based on my digging, it seems like there are two major recommendations for mold mitigation. One is to remove the moisture from the air. This can with a dehumidifier or possibly by deploying large amounts of moisture removers like desiccant cartridges or DampRid. Another tactic that seems to work is keeping the air moving around your storage place, so it never really becomes stale. A final recommendation is to simply visit the unit frequently enough to remove any water and to change out the DampRid, if that’s your line of attack.
My storage unit’s power is currently disconnected due to ongoing electrical work in the building, but once the juice is back on, a dehumidifier will be my first line of defense. But until then, in the absence of a dehumidifier, how do I stop mold from growing?
It looks like a lot of folks use desiccant bags inside stored cars, boats, and RVs, so maybe that is something that I will try. In the worst case, I’ll just waste a little money. Ultimately, I’ll use a dehumidifier, DampRid, and an ozone generator to aid in my cleaning.
As for killing the mold in the latest victims, my wife seems somewhat excited to help out. I won’t yuck her yum, so if she likes killing mold, I won’t stop her. I am not at all worried about cleaning up the cars.
What I am worried about is making sure that mold cleaning doesn’t become a regular thing for me. I have only partial confidence in my plan to deploy a dehumidifier, a fan for circulation, and DampRid. Here is where I will turn things over to you: How do you keep vehicles in seasonal or long-term storage from getting moldy?
Thank you all for the suggestions! I think I’m a bit more confident in what I’m going to do now. Electricity to my unit should be restored soon enough. Looks like my list of priorities will be air circulation and reducing moisture in the vehicles themselves. We’ll see what happens over the winter!
Also, sorry, Box Rocket, I have inherited David’s disease. I’m not interested in selling. But I do drive them from time to time, which is why they all have inflated tires and aren’t buried under inches of dust. 🙂
Dehumidifiers are certainly helpful but actual active (powered) air circulation is what is really needed here. I would consider finding a different storage facility if possible. Good luck.
Agreed. Ventilation first.
Your storage building should not be so humid, even when it is humid outside.
I hope you’re aware damprid can be dried out and reused.
It comes in some large sizes too.
Very humid here, so much it just spiked so the AC is on again.
Dehumidifiers make a *huge* difference, and at least one is needed here. If she can’t easily circulate the air of the entire unit, she can at least pull moisture out of the existing air. Only factors are electricity source and somewhere to run the humidifier’s water drain line.
Sheryl is a rare saint for doing the mold job! I personally use a dehumidifier with a built in pump but you can’t let it get cold so you need a heater and that helps, too.
Dehumidifiers will change your Life.
I use a Midea Cube with a built-in pump and I’ve never had to empty it. I would probably recommend at least two for your space since dehumidifiers need to be sized for a space like air conditioners.
An ozone generator might work, but it would have to be big and left on for quite some time due to the size of the space. If there’s a place near you that rents them, give it a shot.
Instead of an Ozone generator how about building a giant Tesla Coil. All those lightening bolts are sure to create mega ozone.
This is the kind of outside the box thinking I come here for!
This is probably a good idea in the short term. Something like rotating it through the cars for a few hours each just to kill as many spores as possible so it’ll take longer for the mold to come back if the moisture level rises. Or one of those chemical chlorine dioxide tablets plus a battery-powered fan, but the smell from those can kinda stick around an obnoxiously long time.
Not sure about the space as a whole – dumping enough ozone into the whole warehouse space to make a difference might be hazardous to neighboring units.
Ronald Finger has a YouTube video where he used ozone to deal with mold in his Pontiac Fiero restoration.
I love his channel!
I borrowed one of these when my old WRX developed a mold issue (both front seats were pretty well covered in it… rears were fine, I suspect oils/dirt from bodies in the seats were to blame). I wanted it for extra insurance, but I have heard excessive ozone use can cause plastics to age prematurely, so you might want to use it sparingly. I have no clue how much it helped, but I never had the mold return in that car (driving it more regularly probably helped… but that first year of COVID was rough).
So I have a couple of cars stored in my damp old PNW garage and an old teardrop travel trailer. I use to battle mold in the garage and did damp rid for a few years. Then I decided to grab a cheapo Peltier effect dehumidifier with low expectations. Well now I have three because it actually worked great. It removes a fair bit of moisture from the air and I find myself emptying the reservoir once or twice a month. They also have a fan to do their thing so inside of a small space like a car or teardrop it keeps air moving. I haven’t had any issues with mold in my cars since! But obviously it requires access to power. They draw a little bit over 22w each so it comes out much cheaper than buying damp rid or using power to “refresh” reusable desiccant. These are the ones I have. The first one was a larger discontinued model. https://www.amazon.com/Pro-Breeze-Electric-Dehumidifier-Portable/dp/B01DC5PPWM
FYI Peltier coolers/dehumidifiers are incredibly inefficient.
A traditional humidifier which uses a refrigeration cycle will pull out far more water, run less for a given setpoint, and use less power doing it.
https://m.youtube.com/watch?v=j_QfX0SYCE8&pp=ygUkVGVjaG5vbG9neSBjb25uZWN0aW9ucyBkZWh1bWlkaWZpZXJz
Yes I remember watching his video about them, which came out years after I bought my dehumidifiers. Its also why I said I had “low expectations” as the drawbacks of the Peltier dehumidifiers was well known before Alec’s video. You get what you pay for. If I had a properly sealed free standing garage? Sure, I would have proper HVAC in it or maybe plunk more money down for a whole garage dehumidifier. All I am saying was that in my use case, it worked. Price was right, form factor was right, cost to run here is about $.04/day, and results were optimal. Cars are small and I don’t have standing water in the vehicles. I am not saying that would work for everyone. Much like the little mini fridges he demonstrates, people have unrealistic expectations of the technology.
Most modern dehumidifiers have a hose attachment where you have it empty in a drain and don’t need to worry about dumping it
Yea I had borrowed one for a bit to help out in drying a room after a flood a few years back. It had a hose for it to drain by itself. That one was a bit too large for sticking inside of a car though. The smaller cube ones might be doable for sticking in a car but they certainly aren’t cheap. If I had a larger trailer I might be tempted to splurge for one. Buying multiple is just a non-starter however. So far I’ve been ok with checking on my cars from time to time and dumping the traps as needed. I actually use it to help water my herb garden in the summer time instead of dumping it on the ground.
My 2006 Touareg was way worse than that after sitting outside for several months with a clogged sunroof drain.
It was a PITA, but it’s all back to normal now. Notes
1. Vacuum and dry wipe up as much mold as you can FIRST.
2. Scrub everything with vinegar, be sure to get all the nooks and crannies. You will probably want to pull out the seats.
3. Dehumidify, dehumidify, dehumidify.
4. Deodorize and sanitize with chlorine dioxide and ozone.
5. Wear a respirator!
Good luck!
Pretty well 90% of my household cleaning is done with industrial cleaning vinegar, baking powder, lemon juice and salt. However after I had mould in my Corolla headlining ( a felt over compressed board type ceiling due to the sunroof drains being clogged I bought some commercial bio enzeyme cleaner and gave it a scrub- can recommend. Can definitely recommend that dehumidifier for when you recieve power.
it’s an old people solution, and cheap! Big opened boxes of baking soda will do the trick. I had this issue in the past for stored things, too. Grandma was right, cut the box off of the top of baking soda, put it in with the stored stuff, and it will absorb the moisture and make it smell good, too. Sometimes the old methods work the best.
I learned this from working at dealerships and it’s the easiest and best thing to do.
It also prevents it from happening and restores without cleaning!
You need a mold enzyme fogger. I had a 2000 Lexus LX 470 and when I got my GX 550 I left it in my driveway for way too long (9 months) and mold grew on the headliner and seatbelts. I put the mold enzyme fogger can in one evening and came out the next day and all of the mold was completely gone. No odors. Dry feeling. No work to do.
Then the enzymes stick around and prevent the mold from returning also, so after I did this the mold never returned.
https://www.amazon.com/DWD2-Protect-Automotive-Mold-Treatment/dp/B0875J27C9
This is what dealerships do. At least ones that know what they’re doing.
Oh, that’s more practical than my suggestion of gamma rays from a lump of cobalt 60.
Without steady power, you are up a creek.
Unwelcome microbes are the bane of any homebrewer, and once they move in, no amount of dehumidifiers, HEPA filters, UV lights, and bleach will ever truly rid you of brettanomyces, lactobacillus, acetobacter, or molds. There is a reason most breweries that regularly serve sours and wild beers have separate facilities for those
Once you get it all cleaned up both Chlorine dioxide and an Ozone generator are great for sanitizing and deodorizing.
I like these Vacplus water absorbers: https://www.amazon.com/dp/B0BGBK3GJ9
But a “real” dehumidifier is the only thing that will actually work.
When they ship cars they normally fill them with desiccant bags and those damp rid containers. I leave a damp rid of two in my trucks at my farm because it gets humid. A dehumidifier that has a hose connection is also very useful. I run them in building with the hose running out and don’t have to worry about dumping the buckets. Or you can put one on top of a 55 gallon barrel and use the water for something.
I am going to give you an all of your readers a fantastic suggestion that was given to me 25 years ago or so. 20 mule team borax. This is one of the greatest products ever to eliminate mold and any odor associated with it. It will also help prevent future growth. I usually mix a solution fairly weak with water and wash with it. The mold will not grow back. Check to make sure that you know it doesn’t damage any sensitive fabric, but most auto fabric should be relatively immune to it. I had a pair of shoes this is how the story begins. I used to hike and I go through streams and they would pick up some nasty mold or bacteria. I used pure bleach to wash them. The smell came back. I used ammonia pure ammonia smell came back. A friend of mine suggested I sprinkle 20 mule team borax into the shoes completely covering them put them in a bag for 24 hours plastic sealed, then wash them, no more odor, perfect. I would try the 20 mule team make a light solution after you clean it in any other way and I don’t think you’ll ever have mold come back to those fabrics again PS it’s really cheap stuff all things considered and it’s environmentally safe, etc..
I would have just left the shoes outside.
Not everyone is lucky enough to live right next to a Borax mine.
20 Mule Team is a brand. You can get it at Target
It’s also popular among blacksmith as a flux (for keeping oxygen away while forge welding)
Drop light with a 60w “rough service bulb” since those are still legal in incandescent versions or if you get lucky and find someone with a stash of old incandescent bulbs. crack the window just enough for the cord to the light to pass through.
I’d try two tubs of Damp Rid in each car. But you should probably check them every other week or so to see if they need to be changed.
And if you use a dehumidifier, you’ll need a drain to send it to, because otherwise it will fill up in a day or so and then stop running. And if you drain it to the floor, it will just go back into the air.
You could put the dehumidifier up a little higher and let it drain into a 5 gallon bucket (covered). It’s probably better to run some sort of flexible tubing to the door, maybe using a hard pipe to run under the door itself so it doesn’t get crushed (assuming garage door with soft bottom seal). This could allow critters some entry where the seal isn’t making contact with the ground, so pack any voids with stainless steel (you’d have to do this every time you leave, but it’s not a huge deal).
I think you want something bigger than a 5 gallon bucket.
We run two dehumidifiers in our house and they probably generate a couple gallons a day and we’d be emptying them daily if they weren’t plumbed into the drains.
I’ve never really run a dehumidifier, but that sounds like a lot of water.
It’s typical for an area that sees the outdoor humidity in the 80%+ range most of the year and we try to keep it in the 50s inside…
I have a dehumidifier with a built in pump. A small 1/4″ tube then runs to the tub or drain directly.
However, draining to a drain in the floor would be fine. That drain will always have water in it anyway in the trap.
Unless you don’t add water to the drain from time to time. I’ve been in four plus month unused offices to prep for a move in and all of the bathrooms stink to high heaven because the trap water has evaporated.
Sure. There are exceptions to most any statement. (Even to this one.)
But draining to a floor drain certainly won’t lead to any more evaporative surface area then a normal functioning drain.
I’ve had decent luck with the rechargeable metal desiccant canisters. I will heat them in the oven to recharge, and then seal in a gallon ziplock to keep them away from moisture. I then rotate into the car as the other becomes saturated. In Louisiana, 1 canister in a closed car, parked in a barn with concrete floor, usually takes 3-4 weeks to saturate a canister. I’ve had zero mold issues since I started the rotation.
I am a property manager at a storage facility in PA. FOR $6.99 you can buy a quart container of damp rid. Place one in each sealed vehicle according to directions during storage and you are good for at least 3 months. Im sure Sheryl will appreciate the effort. Once you get mold even cleaning might leave spores that come back quickly if the humidity level reaches the right level
This. Look into anything that boat owners in northern states use when putting their boats into storage – and almost all of them will use damp rid. The same applies to RVs, but boats are obviously more wet by nature and even when in storage are often just barely away from the water in the marina’s storage area.
Move to California.
But, yeah, getting rid of the moisture in the air will help. A dehumidifier should do the trick.
That only applies to Southern California. The northern half of the state can get, and stay, pretty wet.
Yeah I lived in Eureka CA, the saying was you can tell a tourist from a resident because residents had webbed fingers and toes due to the ever present rain and humidity
Ha I stayed at a B&B beach house in Eureka this past August so my family could see the redwoods and sequoias. The northern California coast was of course gorgeous as well!
The extreme option is to move to a drier place. Here in the Oregon High Desert humidity is usually 30% so mold rarely grows and your potato chips stay crisp. There’s the extra bonus of no road salt, although 300+ sunny days do cause UV damage. On the minus side the Bend area is expensive and 200 miles from Portland and the Coast. This is offset by mountain roads, desert roads, lakes, rivers, and OHV trails on your doorstep.
Bend is the northernmost city in California!
My father would want me to admonish you for recruiting people to move to eastern Oregon so as to keep it pristine and empty!
I generally refer to the place as the fastest growing Californian city. When we moved to Bend our neighbor was visibly relieved when I said we came from Beaverton. Bend and Redmond are lost causes at this point.
Isn’t Bend in Oregon and the northern most point there? I had an interview there and I flew into Portland airport if it was in northern California it would have been the Arcata International Airport. I kid about intl
Bend is actually almost dead center in the middle of Oregon The California jokes are because so many Californians move to Bend. The northernmost city in Oregon is Astoria at the mouth of the Columbia River. Also you got shortchanged on airports, Redmond is only 20 miles from Bend
Crescent City has entered the chat!
I have actually been there great city little airport
You may think you put a vehicle away dry and then closed the windows.
The problem being warm summer/warmish fall air can hold a lot of moisture.
Come winter it will probably be raining in the car, before it all freezes up.
I like 99% isopropyl alcohol for cleaning things up, I’ve also used CLR Mold & Mildew Clear. Test an unseen area for any damage when throwing chems at a problem.
Last resort is the ozone generator, works great, maybe dangerous for lifeforms and may severely reduce the lifespan of rubber and some plastics.
Ventilation and air circulation is your friend.
I’m a fan of fans.
Heating and a cooling can help or not, moisture is sneaky and can take you back to square one,
Keeping air moving is definitely a good call if you can swing it. Windows open enough to allow air flow. If you want to get serious about it you could use a few inline booster fans or indoor hydroponic fans connected to flexible ducting dropped into the open window.
Those may be more effective if plumbed into the intake side, but I don’t know why I think that. They don’t need to run all the time. You can have them on timers, or by humidity sensors. The humidity sensor things are readily and relatively cheaply available hydroponic supplies and the timers can just be the standard ones you use for holiday lights.
Apparently, this is an issue for the Sultan of Brunei also:
https://youtu.be/5DeT5TS2_cs?si=Kfx8TdP01dFw6jXV
I have honed it down to a couple things, along my 25+ yrs in the tropics: if you pay its a piece of cake and you have no molds. 1) put a good recirculating fan 24/7; 2) put a small (I use a 12K BTU) AC on “dehumidify”, also 24/7, for 1000 ft2 and drain it to outside. Keep the place sealed from outside, but everything inside exposed to the circulating air. Everything else (dedicated dehumid/damp rids/heater bars/etc) winds up costing more in the long run.
Actually a swamp cooler might be a better less expensive investment but still damp rid in all cars unless you are driving them.
I imagine there is too much humidity for efficient operation of a swamp cooler in Mercedesville.
A swamp cooler by design/definition adds moisture to the air. There’s a reason evaporative coolers work better in Arizona than they do in Florida.
Since you live in a humid area, even a “dry” car has humid air in it when parked.
Your options for airflow may be limited unless you can create ventilation holes in the garage.
Your idea of getting a humidifier is best for the long-term, I would strongly suggest one that you can attach a hose to and route it outside somehow to self-drain so you don’t have to worry about emptying the bucket, which can be an every-day task in humid areas.
For the short-term, I suggest putting some DampRid INSIDE of your vehicles to keep the interior air dry. It will be nearly impossible for DampRid to dry out the entire storage area, but the inside of a car is totally doable. Just don’t use the ones that can spill if you forget about them (little buckets of DampRid), maybe consider the Hanging ones designed for closets, you can hang them from the coat-hanger or similar thing most cars have so it is visible and less likely to be forgotten.
Airflow is your friend. Can you increase air circulation in the garage somehow?
DampRid can help some. But it’s sort of like using a roll of paper towels to wipe up a lake. If your area is humid, you will be surprised how quickly the damprid will be used up. You may have to change it out weekly to monthly.
Also, be aware that ozone is caustic to all organic products. It may kill mold, but it can also deteriorate leather as well as some types of plastic and rubber.
Dessicant is used frequently in boats. Seems to work pretty well compared to boaters who don’t use them. I think there are some that you can heat up to “recharge” them, which might be an especially good idea with so many vehicles. As others have mentioned, you want air flow, too. You’ll get (more) spiders moving in, but it should reduce the problem if you can also get air flow through the storage area itself.
FOR SALE: Dessicant
“Just needs a charge”
Ha ha
I’ve always just run a dehumidifier, maintains at a max of 50%, except during some extended periods of heavy rain when it can sometimes get a little overwhelmed and let things creep up to 60%
Figure keeping excessive moisture out of the air has to be good for more than just inhibiting mold growth
I wonder how practical it would be to sell several of the cars to put together a down payment or start building a barndominium…. Would be such a cool plan for your vehicle-centric lifestyle!
You are spot on I suggested that to Mercedes in one of the other posts she put up. The whole process of the barndominium build and divesting of some cars, etc. would make wonderful content.
I’ve used DampRid in my Jeep to great success against mold, but the best prevention is keeping fresh air circulating and not letting the air stagnate. Drive your cars!