We all know it. We all hate it. And if you live in a tiny house, you likely have all seen it lurking somewhere in your home.
Mold is a four-letter word that can mean anything from a minor annoyance or a legit illness-maker for those who are sensitive. Thankfully, there are multiple methods of reducing the added moisture in your tiny living space that can help reduce the likelihood mold even forms, and there are some good mold killer products out there that we've recently used with success that we'll discuss below.
First, however, please take a minute to read Andrew Morrison's post on mechanical moisture eliminators plus some additional moisture-reducing building tips below. Andrew and his wife, Gabriella, are the originators of the hOMe tiny house that is now being produced by EcoCabins, the primary sponsor of the Tiny House Jamboree. Andrew definitely knows a thing or two about making quality tiny houses and how to deal with excess moisture build up in cold climates in particular, and the suggestions he makes in his post are particularly good if you want to actively remove moisture from your house. The biggest difference between Andrew's post and ours is that he focuses primarily on prevention methods, where as we have actually experienced some pretty nasty mold and cover things to use to get rid of it when it does happen in addition to our dehumidification tools. I've been meaning to update everyone on our issues anyway, and the Morrisons' great post reminded me! ☺️
Here's his great post:
For those of you who want to know about some additional methods of moisture reduction, here's a list of what we are currently using based on type (passive, hybrid, or active) and one extra thing we plan to try. You'll see the two electric appliances we picked up listed here, too, because we felt we needed a more immediate and noticeable reduction in humidity than our passive methods provided. We hope once we get the humidity % down we can stop the active dehumidification and rely on fresh air on good weather days and the passive options to reduce our electric pull.
- We started using DampRid disposable products to suck up extra moisture without any power needs (popular on boats and RVs and found at Walmart or similar stores), which use calcium chloride in bags you hang or jars you set in open areas. They are inexpensive and require nothing other than airflow (which, incidentally, you should provide regularly to mold-prone areas anyway), and we have hung them in our three trouble spots: the loft, the front nook, and the kitchen. So far the bags are about 1/3rd full with the nook one being a bit closer to half full than the others. We are also going to pick up a jar version to tuck into the furthest corner under our son's room as I discovered mold had formed where a basket of extra linens had become wedged behind the clothes cube and the back corner. I've already killed the mold with a spray we've found to work well (more on that shortly), and in addition to the DampRid we'll be making sure we regularly move the cubes under his bed to promote airflow.
- The this next passive method may or may not work, but it does have some other benefits to it. While I'm not expecting much immediate relief of our current humidity levels, I won't deny I think this would make a great, natural addition to our long-term moisture control methods: air plants. Granted I've read some conflicting info on just how much additional watering air plants need beyond what they suck out of their environment, but since they're low maintenance and don't need to take up counter space, I'm thinking I'll create a little installation of them in a couple different areas of the house. Besides, who doesn't love a little live greenery in their tiny house?! ☺️
- The first dehumidifier product I picked up is the EvaDry silica gel hybrid dehumidifier that can be placed anywhere you want, but when they're full (the gel changes from blue to pink when capacity is reached) you take them outside and plug them in to release the moisture into a well ventilated area. I bought two of these on Amazon for $20 each, and they can be laid flat or hung with the included hook. The ones we have say they can absorb up to 6oz of liquid, and so far ours are still deep blue. One is hanging by the front nook window, which has continued to be a bit of a problem child, and the other is wedged at the head of our bed near the tongue-end window. I'll update this post once they are finally full so we have an idea of how long it takes to fill them up.
- I want to mention here that our Kimberly gasifier wood stove by Unforgettable Fire LLC is another hybrid method of dehumidification. No, it doesn't require electricity, but you do have to burn fuel (wood) in order to heat up and dry out the air. As much as we adore our Kimberly, it has simply been too warm to use her daily and reap the reduction in humidity benefit that comes with use.
- We also broke down and bought a small EvaDry mini electric dehumidifier that, unfortunately, has to run all. the. time. and is definitely louder than I'd like. That said, it has sucked several cups of water out of the air already (I've emptied it once just before the "full" light would have been triggered), and we keep it on the edge of the loft directly above the kitchen to catch any extra moisture that doesn't escape out the window when we cook. This is also from Amazon and cost $54
- We didn't install a kitchen vent like the Morrison's have mostly because we have a much smaller kitchen with a double hung window smack dab in the center of the wall above the countertop. We have been opening the top window sash in the kitchen and a bottom sash on the other side of the house to create a cross breeze that forces the steam out while cooking, but it wasn't always working as well as we'd like. Instead of boring out a giant hole above the window for a permanent vent, we opted to pick up a small, portable O2Cool 8" square fan that can be run on either batteries or AC power, and we instead pull the top window sash down enough to wedge the fan in (facing out, not in of course) and cover the remaining open space with a piece of cardboard while opening an opposite-side window just a little bit. It's not pretty, but it's portable, storable, functional, and cost effective. Can't beat that!
- We also have a Vetus Marine 12V vent fan to install in the wet shower side that was a recommendation of Art Cormier, a Tumbleweed workshop presenter and dweller of the Tiny SIP House. That's something we bought early on in the build but just never got installed, and thankfully not having hasn't been an issue since we've almost exclusively been showering at the bathhouse, gym, or Rec Center depending on what we've got going on at the time. Once we start using our full-time, however, we will definitely need to use that vent. It's low voltage - as is all the wiring in both our wet and dry bath sides - to prevent shock, and as the name suggests, they were designed for the boating industry. Art has a great demo video with all the part numbers on his YouTube channel that's worth checking out.
DEALING WITH EXISTING MOLD
Now, if you DO develop mold despite your best efforts, there's a spray we can recommend after using it on 7 different wood windows where we've had problems. Bear in mind that we actually performed a series of steps to actually remove the existing mold in addition to mitigating its return (more on that below), but so far we've been quite pleased with the Concrobium Mold Control spray we spent $9 on at either Lowe's or Home Depot - can't recall which. This stuff is recommended by Mike Holmes, the HGTV star of Holmes Inspection and a few other building-related titles, though that's not why we bought it. This one gets sprayed directly onto the mold, and as it dries it actually kills it. It's non-toxic and had no noticeable smell I could detect, which is helpful in such a small space. So far, none of the windows we treated with this stuff have had regrowth, though let me provide you the actual steps I used to removed the mold:
- Scrubbed the mold with undiluted bleach and an old toothbrush. Let soak for 30min with all 5 loft windows open.
- Took a heat gun to the remaining wet areas very carefully to make sure the wood was truly dry.
- Sprayed Concrobium liberally over all the exposed wood that had had mold on it plus a few spots I thought might be prone to it later. Let soak until dry, which was around 5hrs in this case.
- Dried remaining moisture with heat gun again.
- Applied Rustoleum oil-based stain to one window, but the other 4 haven't been stained yet and are STILL mold-free despite repeated exposure to wetness/ice/inside moisture buildup.
I didn't have as much luck with the Concrobium on the big nook window I painted with milk paint, but I also just realized I never tried the straight bleach technique. Whoops! Needless to say, not remembering that fact, I decided to try to other mold spray, Mold Armor, to see if it would kill the stuff. It's actually marketed more to remove mold stains than kill the mold itself, and I found out the hard way you MUST ventilate the area you're using it in. I dumbly thought it was like the virtually odor-free Concrobium and sprayed it liberally on the window, but even though I didn't actually notice the smell initially, Brand walked in from outside and had his eyes start watering immediately. Whoops!! Open went the windows post haste, and I haven't used it again. Now, that said, it worked!! We haven't had any new mold growth on the big blue milk paint window since then, and I did nothing else to it at all. No scrubbing, drying, or bleach. Sadly, I think I'm going to have to remove all the milk paint and start from scratch to make it look pretty again, but that's a small price to pay to not have mold again.
Speaking of of keeping the windows from molding up, here's an observation I made during the removal process:
Mold only appeared on the windows either with no stain of any kind OR with water-based stains like the milk paint big window or the metallic acrylic paint used on the two bathroom awning windows. None of the ones where I used an oil-based Rustoleum stain or white paint developed mold, which included all 5 of the double hung windows on the main level excluded the largest one.
Now I'm staining the remaining 4 loft windows with oil-based black paint, and I'll seal the acrylic painted ones with polyurethane. I will add, though, that the milk paint window DID get a coat of poly on it, yet the mold kept on chowing down on it. After I strip it off I'm going to seal the wood with poly first before reapplying the milk paint and sealing a final time with poly. Hopefully that'll deal the final blow to any molds trying to eat that pretty blue-green paint!
I'll be researching a few of the products the Morrisons mention in their post, because we sure don't want to keep dealing with this fuzzy, nasty stuff! We do have a gauge that tells us what our indoor humidity is, but I'm starting to wonder if it's accurate. Some days it says 37%, and others it says 50%, even if there haven't been big indoor or outdoor temperature changes. Hmm. My understanding is that at anything above about 40% humidity, mold will have the chance to grow. We'll just have to keep chipping away at the overall moisture volume with all three types of dehumidification as best we can until the weather warms up enough to keep the windows open all the time.