Tiny Home Moisture Complaints
Black Mold on Tiny House Wall.
It happens every autumn like clockwork. When temperatures drop, we close the windows, turn on the heat, and start receiving tiny home moisture complaints. Moisture condenses on the cold windows, water pipes, and other cold areas.
If conditions are right, moisture can also condense within the walls. Mold will grow and dry-rot will begin. Enough moisture can condense to actually pool under your flooring, on the sub-floor. Soon you have real problems.
Two Things Need to Happen to Reduce Tiny Home Moisture Levels
- Humidity needs to be removed from the air mass, or the air mass needs to be expelled and replaced with dryer air.
- Air must be moved into and out of every corner of your tiny home to prevent “micro-climates”
1. Removing Humidity and/or Humid Air
Sometimes just cracking a window open is all that is needed to alleviate moisture, but then you will be wasting heat energy by bringing in cold air. Note the Heat Recovery Intake system shown on the left as a possible solution. This unit recovers 86% of the heat while bringing in fresh air.
TwinFresh single room Energy Recovery Ventilator is designed for extract and supply ventilation with Energy Recovery mode. It is an efficient, healthy way of exchanging the polluted, stale air in your home with fresh outdoor air year round, while reducing your heating and cooling bills. Whisper-quiet operation, wall-through installation design, and various operation modes ensure convenience and comfort.
Modified passive solar heat box
A fresh air intake vent can be used, and should be standard equipment in a tiny house venting situation. But in winter months, you will be sucking in very cold air and wasting energy. One solution might be a “passive solar heat box.” This is a very clever way to heat the air before it enters the house. This is a new idea and still in the hands of do-it-yourselfers.
Passive heat boxes are designed to pull air from inside the home, through the heat collection box, then back into the home. The passive solar heat box will need to be modified to draw outside air, thus providing fresh, preheated air into the home.
It’s also limited to daytime use, but these solar heat grabbers are worth considering. They can produce enough heat to keep a tiny home warm during the day.
Check out my web page for sources of passive solar heat boxes and the video showing the passive solar heat box shown in the picture.
Visit this website for Passive Solar Heat Box DIY instructions.
Remove moisture under mattress
Moisture collects in your mattress. Venting under the mattress is a must. If your bed does not have a frame or a raised area underneath allowing airflow, consider installing an “Anti-Condensation Mattress Underlay.”
Especially useful for RV and tiny homes to help solve the issues of mold, mildew, and dampness.
HyPUR-Flow is designed to prevent moisture build-up underneath your mattress. It will elevate your mattress about 1/2 inches to create unobstructed air flow, which will help prevent condensation & moisture, keep the bottom of your mattress dry, while allowing any potential moisture to evaporate.
Here’s more information on custom sized mattresses, RV sizes, and fitted sheets.
Humidity Removal Game Changer
The new ZeroBreeze, Mark 3, Portable Air Conditioner is excellent at removing moisture. This brand new device is capable of producing 5280 BTU cooling and also has a heater function. The Mark 3 weighs less than 20 lbs. and is the same size as the revolutionary Mk2. It has a thermostat you can set with the remote control and it will heat or cool as necessary.
But the big thing for moisture issues is the Active Drain System. The condensate is pumped out and can be sent upward 59 inches. The ZeroBreeze Mk3 can be permanently mounted with the included hoses or used portably with the batteries. You can send the moisture to a drain or recycle it for other uses.
It will be available soon so check back here for the latest news.
Automatic make-up air damper
Broan NuTone SMD8 8″ Automatic Make-Up Air Damper with LinkLogic: Synchronized to only open during fan or range hood operation to avoid wasting energy. It does not let unwanted air into the home when not needed. This improves ventilation efficacy by providing fresh air from a known location to replace exhausted air. See its use demonstrated in the YouTube® video below.
Heat recovery or energy recovery ventilators
An HRV or ERV is often overlooked. In addition, the installation is often done improperly. They work if installed correctly. See the YouTube® video below showing an HRV installation. It is mounted in a mechanical room and ducted to the far end of the tiny home. The conditioned air is forced to travel the length of the structure, conditioning the entire area.
The wall mounted single room HRV shown here is more easily installed.
Jump to my web page on heating your tiny home for directions on installing heating ducts. The man in the YouTube® video is actually installing this HRV into a small home.
Pay attention to these items in this YouTube® video
- Notice the holes around the “raised” propane cook top. He is supplying combustion air from a large vent in the cabinet below.
- Notice that he has actually built air ducts into the house. These ducts bring the fresh air from the ERV/HRV to the far side of the house so the air travels throughout the entire structure. This is the only time I have ever seen a tiny home with air ducts. I think we need to incorporate this into every tiny house design.
2. Air movement
The shower will be your biggest moisture producer. One of the easiest ways to vent this moisture could be to install a skylight that opens. or vent fan directly over the shower enclosure (most homes have it over the commode). See more about skylights here.
Install a humidity sensing fan switch like the one shown here so the fan stays on until the humidity is removed.
Bathroom Exhaust Fan
Venting tiny home moisture from a shower is critical. The fastest way to reduce tiny home moisture is a vent fan in the bathroom.
Here is a good ceiling vent fan.
Maxxair 12 Volt Rooftop Fan/Vent
Control fan speed, thermostat and air intake/exhaust flush-mount ceiling keypad. Long-life, sealed ball bearing 12-volt fan motor moves over 900 cubic feet of air per minute, quickly and efficiently pulling fresh air in and removing hot, stale air and odors.
It is designed for an RV, but comes with a flange large enough to accommodate a tiny house roof. Click on image to see details.
Read more on tiny house venting and air movement on this page of TinyLifeConsulting.com
Uses Fans To Get Air Moving In Enclosed Spaces
Use small fans to get dry air into enclosed spaces like under a storage bed.
When venting an enclosed space you need and inlet and an outlet. The fan shown here can accomplish both functions by setting the direction of each fan individually, one blowing in and the other blowing out. Even though they are super quiet you might still here them purring at night.
You will need to supply 110 VAC power but it only draws 14 watts.
For more information about unique fans visit this page: Properly Venting a Tiny House
Mold is the #1 Problem with Tiny Home Moisture
Mold killing products
Zinsser Mold Killing Primer is a first-of-a-kind, EPA-registered coating designed to literally kill and block mold. No need to clean or pre-treat. Just apply over existing surface mold areas to stop the spread of mold and prevent future mold growth. Use any top coat to complete the project.
Not recommended for use under self-stick tiles or wallpaper.
Kilz Mold & Mildew Primer, Sealer, & Stain Blocker
Specially formulated to prevent mildew (and potentially mold) from growing on the primed surface before paint is applied, KILZ Mold and Mildew Primer contains active ingredients that are registered with the Environmental Protection Agency.
This mold and mildew resistant film protects the primer film, sanitizes the surface it is applied to against fungi organisms, and helps ensure a fungi-free primed surface for painting. KILZ Mold and Mildew Primer blocks stains such as markers, lipstick, food stains, smoke, nicotine, grease and more.
Best of all, it’s very inexpensive. Reasonably priced on Amazon. Click on image to see details. $37.98* at The Home Depot.
For more products to use during a travel trailer or RV remodel visit this page.
Concrobium 25326 Mold Control Spray, 32 oz
- Use to eliminate mold, mildew, musty odors and prevent regrowth
- EPA-registered formula crushes mold spores as it dries and leaves an invisible barrier
- Odorless solution cleans between 80-110 sq. ft. per 32 oz. bottle
- Unique mold spray contains no bleach or harsh chemicals, safe for use on a wide range of surfaces
- Simply spray onto affected area and allow to dry – no scrubbing or rinsing required
- Concrobium mold control effectively eliminates existing mold, prevents mold re-growth, and eliminates musty odors with no harmful chemicals.
For more Mold Killing Products see this page: Eliminating Mold and Odors in Your RV or Tiny Home
RV and Travel Trailer Owners Swear By This Stuff
Instagone Stain Remover Multi-purpose Stain Remover
This is the product you want to remove stains from that fabric roof. Instagone remove mold, mildew, and rust stains.
“Spray it on, watch them GO! No rubbing, scrubbing, or wiping! Spray it on and the stains are gone! InstaGone is unbeatable on mold, mildew, water spots, soot, nicotine and other stains. Works on acoustical ceiling tiles, popcorn ceilings, caulking, tile, masonry, plaster, stucco, PVC patio furniture and more! Works on: Mold Water Stains Mildew Nicotine Rust Stains Soot & More.”
Click on image to see details on Amazon.com.
Very helpful, Kevin. Thanks for sharing your knowledge.
Well done Kevin.
Really important, health is the key to everything about architecture.
John
Thanks so much for sharing your wisdom on this topic. We are building our Tiny and want to “get it right”! Thanks again!!!
Thanks Anne. I study hard on each topic before posting. I’m glad it was helpful for you.
As someone who lives in a tiny in a cold weather climate I can confirm that moisture is the number one issue. We have a small closet sized dehumidifier that works great and it runs steadily in the winter. We also have the Lunos air exchange system but in the winter it can’t keep up. We also have RV moisture collectors tucked in several places. But the best way to deal with moisture is our small wood stove. It creates a wonderful drying heat. Even with all that we often just take a cloth and wipe all the moisture off the windows regularly. Our wood stove allows us to crack open a window if needed as well.
I wish you hadn’t put those ads on this article. Those things do not really kill mold. Anything moldy has to be cut out and replaced wearing protective gear and that includes mask. Because killed mold becomes mycotoxins, basically a very small particle that is a gas. If you get this in through your skin or lungs or nasal passages, it has invaded your body. How do I know? I have mold sickness. 10% alcohol solution in water wiped in one area then throw out cloth or stiffer and continue. Otherwise you just spread the mold around. People can get very sick like me. Be careful. This is the one thing I’m stuck on with Tiny’s right now after living in a small camper. This is one reason people might consider container homes or a box truck or bus build out.
Hi Megan. Thanks for the information. I’m sorry you have such a sensitivity to mold. It can be a real problem. As far as the products go, they were recommended by readers as the solution to their mold problem. I myself remediated an entire house with Kilzs. But, you do need to read their claims closely. That is frequently enough for most of us. Mold should not be ignored.