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Moisture in the Yurt from Condensation

Jafo

Jafo

Administrator
Staff member
So I have been looking around online trying to come up with some ideas for combating condensation in a yurt. It seems to be a number one topic for many who have moved into a yurt full time in colder climates.

I have been of the opinion that venting your yurt is necessary and I stand by that. Cracking open the yurt dome will probably do quite a bit towards relieving moisture issues. I think if you are going to put insulation in your rafters, there should be consistent a gap between the insulation and the top cover. This gap should extend all the way to the dome and the ends near the wall and the dome should be opened slightly to allow for airflow.

I think there is also more to the equation. The yurt cover is generally thin as it is made out of some sort of fabric or vinyl. This makes for quick condensation when any moisture comes in contact with it while it is cool. Reducing the humidity inside the yurt should also be helpful.

Besides an ordinary dehumidifier, there are other ways to remove moisture from the air. I have never tried these, but they came up repeatedly in my search:

Charcoal briquettes - These supposedly work very well.

Rock Salt - Reportedly does as well as charcoal, but has another benefit for us in colder climates.

Damprid - A commercial product that removes moisture from the air (link).

I haven't tried any of these myself but would love to hear if any of you have.

Do you have any other thoughts or suggestions?
 
To my way of thinking, utilizing the natural air flow inherrent in a yurt is the best way to get excess moisture out of the yurt. IMO the well designed modern U.S. type residential yurt, with hot water plumbing, will feature a cap that incorporates an operable vent.

If you have a yurt with a partitioned and hot plumbed bath and kitchen, an operable window at the bath and sink are a good idea. Crack the window. If alot of moisture has escaped into the yurt, crack the roof cap vent as well. Out goes the excess moisture.

As far as insulation installation, leave a couple inches gap at the yurt wall, gap between the insulation and the cover, and again at the roof ring. Air flow naturally carries out moisture if given a chance. Make sure materials that can hold trapped moisture are not in contact with eachother. The natural slope of the yurt rafters assure an air flow, up and out, IF the cap has a vent.

Possibly in the future there will be a miracle yurt/tent fabric that breathes under all weather conditions. Todays breathable fabrics work -sometimes- because vapor pressure of the wearer drives out the moisture. Sometimes. Sometimes not. Remove the wearer and the garment doesn't breathe. How that applies to yurts/ tents etc. I haven't a clue.

I wish I could contribute more, but 'air flow' is what I got.
 
Agreed. When I was a construction helper as a kid, I remember a job where we had to go through an entire condo complex and crawl up in the attics to cut insulation back that was stuffed into the soffits erroneously. It was not allowing air to flow between the insulation and the vented roof and water stains began appearing on the drywalled ceilings. Air flow is definitely key.
 
I've done that 'redo the batt' thing at the cramped space out at the soffit/ plate line myself. Itchy job, huh? lol Air flow is a big deal. Anyone that has seen the results of water logged insulation around a bathroom knows just how important a proper install is. Trapped moisture causes mold, mildew, and eventually the framing rots out. Termites ...man I won't go into that. Nasty. Damp punky framing rotting away, all from a poor install, and neglect about 'keeping out water'. Been there done that. Yeah, venting is definitely key.
 
Heat your home with a dehumidifier | IWillTry.org

This guy describes an interesting quirk of the dehumidification process wherein you can produce about 50% more heat than an equivalently rated (wattage) electric heater while also reducing your humidity. The downside of course, is the associated noise they generate. For this to work there needs to be an abundance of humidity to remove.
 
We ended up getting a large de-humidifier. Between the wood stove and the dehumidifier, we can keep the relative humidity around 40-45 inside.

We gave up trying to vent with the dome, just not a possibility in the extreme cold climate we are in. (We have had 23 < -20'F days already this winter.) We also have a screen insert for our dome, we took that down, and at the suggestion of someone in another thread, put some heavy mil tent vinyl from the fabric store on the top side of the screen and velcro'd it down. This makes a fairy good seal to prevent moisture from getting up in the dome area. Now with the dehumidifier, we keep it relatively dry in there. We get plenty of frost on the inside of the outer layer of tent fabric, but that has been there since it got cold and actually acts as more insulation. We will have to check it out in the spring to make sure it drys when the temps warm up.

We tried using the dome to vent, but it just does not work in the extreme cold. We get way too much frost up there, then when the sun comes out, it melts. 1/2 of it rains down inside the yurt, and the other half, rolls down to the lip of the dome and freezes (think ice dams) to the edge of the dome, at that point, you can't even close the dome anymore.

We also found that too much heat exited through the dome after we got a little ice on the edges and it wouldn't seal anymore. Not a good thing.

Now we keep it around 40-45 relative humidity with a dehumidifier, the temp is always between about 58'F and 68'F (it warms up quite a bit when the sun comes out.), and we are quite comfortable. No more dome problems. We did cut a slit in the vinyl for the dome opener, so we can open the dome up there when the temps rise, but there is little point with the vinyl in there.

We did try cutting a 2" thick piece of rigid foam board in the shape of the screen and put it up there in place of the screen. It worked very well, but we lost all that sunlight, which we were not willing to give up. That is what lead us to try the vinyl insert, which has worked so well, that I think we will stick with it!

Incidentally, you can also hang dry clothes by placing them over the dehumidifier. The dry air that comes out the top of the unit dries clothes quickly, and much more efficiently than a dryer.
 
I wonder if the frost issues on the dome were caused because the humidity and condensation were already very high when you tried to vent it? I guess I mean, do you think it would have gotten that bad had you been venting from the get go?
 
I was venting from the get go, but I couldn't vent 24 hours a day because when it is -25'F outside, we would lose too much heat. I had to close it overnight or we would freeze, and then in the morning it would be quite icy.
 
I understand about the heat loss and ice dam problem. My wife and I had that problem in our first little apartment up in Jackson Wyo. The single glazed sliding door in the kitchen would develope a massive ice dam, rendering it inoperable.

My yurt loses a lot of heat through the roof canvas. Melting snow creates yurt sickles that freeze my entry door and lock solid. I gotta do something about that besides kicking the door open and smack the lock with my axe lol. It's all a learning experience. I'm glad you're getting a solution worked out.

It's kinda funny how the sophisticated cap engineering up there is prone to getting jambed with ice in real cold weather. I'm thinkin one of the layed off NASA shuttle engineers might help solve this problem for cheap, seeings how theys outta work. :D
 
It's funny, we actually tried ALOT of different things. Including:

Mounted a heater upside down to blow warm air up on the dome (like a car defroster)... didn't work, too expensive anyway.

2" rigid foam octagon that fits in place of the screen insert. Worked pretty well, but no sunlight, which we hated, so we ditched that idea.

2" rigid foam octagon held in place by a large painter's pole, so we could take it down. This worked well on the cold nights, but was a pain to put up and take down.

I had to get up there about 4 different times for about an hour each time with a hair dryer to thaw the entire dome and get it functional again. An hour at the top of a 12' ladder isn't much fun, but it had to be done.

At one point we had towels all over the floor because so much water was dripping in!

We have a Shelter Designs yurt, and the only regret we have is that we didn't get some real windows. (we have all canvas windows) So in the winter, it is all buttoned down tight. I know Colorado Yurts has an after-build retro fit window you can put in, I need to find out if Hays and them at SD have something similar. If not, we are going to try to engineer something for at least the kitchen window so we can vent some air by opening a window in the winter time. Plus we will have a little more natural light from this.
 
If you lack any real ventilation via operable cap vent and operable windows, alot of moisture from cooking and bathing is indeed trapped in your yurt. You have to get the moisture out somehow. Normally that is out through the cap, and windows. The cap is at present inoperable, so I would get an operable window installed in the bath and kitchen. I'm certain you will figure a way to get the cap vent operable in inclement conditions in the future.

Windows will allow the excess moisture to escape, just as they do in a standard residential home. Sometimes I just crack the master bath window after a long hot shower and don't turn on the ceiling vent motor. In just a couple minutes the majority of the moisture is out of the bath, and the mirror clears. If we have a couple pots of boiling water on the kitchen stove, and I notice there's a bit of humidity on the window, I'll crack the kitchen window.

You're gonna get this worked out, I'm certain. Good luck.
 
I totally understand the need to get rid of moisture, that is why we have a dehumidifier in the house. I can't use any of the windows (they are all fabric) in the winter, and the dome is not usable in the extreme cold as an air vent. I would literally have to climb a ladder every 2 days with a hair dryer to de-ice it.

We are looking into replacing one of the fabric windows with a real window (as a retro fit.)
 
Great discussion all... thanks for the thoughts to consider.

I'm in my roundhouse/yurt about six months after living in a 12' yurt for 1 ½ yrs. My new one is presently covered with heavy black plastic on the roof as I couldn't get my canvas sewn before the cold set in. It's loud and flaps a bit so can't wait to get it replaced with the real stuff. The "real stuff" I'm using is vinyl canvas.

Presently I get lots of drips from condensation which collects under the plastic and drips through the 4" of sheep's wool insulation I use in the roof. I get the ventilation concept. I'll have opening flaps in my 8' dome I built later this year. But my walls are solid (I wanted lots of windows) so I'll get ventilation by opening my windows. It's not massively cold here in N. Ireland, lowest this year was about -5 Far. -20 c. and that just for a few days.

I may consider the dehumidifier as well, on occasion. though I am off grid, so I have to be careful unless I want to hear a generator all day long!

My biggest concern was the vinyl canvas I'm using. I'd been considering putting it aside and getting cotton canvas, but it is very wet here, and the amount of waterproofing I' think I'd have to do puts me off a lot from that concept. I've learned here that is can be a problem too, so it's about allowing movement of air more than anything... and aren't many of the "industrial" made yurts vinyl or vinylized canvas?
 
Hmm, not sure where you would find it there, but I would definitely go with some sort of vinyl. Your area is so damp that I think you're right not to consider cotton.

How do you power the yurt?
 
Yes, I have the vinyl canvas, cut and ready to sew. The sewing machine too... just gearing up to sew.

I power the yurt with solar. Presently, just two 300w panels powering 6 2v 1000ahr batteries. The whole place is wired 12v, like a caravan or boat, with a few 220v outlets for the LED TV (rated at 25w!) and powering up my laptop, etc. I try to keep everything to 12v since the draw is much less than running through an inverter. Even with my low light I'm mostly good. I had the genny running a fair bit though during the deepest darkest days. Winter solstice here is about 8 hrs of light and quite low in the sky and weak at that.
 
We had a Shelter Designs yurt for a restaurant in Montana and we didn't have "real" windows. we had the velco/vinyl windows and we just cracked one of them by the cooking stove (propane) to get that moisture out. Although this had to be done by going outside, you might try that instead of a retro-fit. Also my time spent living in a camper in the winter tought me a few things about condensation (everything covered in ice, everyday). You need ventilation (even at night) and electric appliances are much better than propane, but it was a constant battle to keep the vents clear and I eventually moved inside. I work now in the HVAC industry and some minimal ductwork and a fan coupled with a humidity sensor could be a solution, also could be fresh air intake if burning wood, but I know...kinda goes against the simpler lifestyle approach
 
Severe the tether,

Installing windows is rather simple once you get over cutting the fabric and the lattice.
email me and I will talk with you further. I have 6 "real" windows in my yurt.

Corina
PS, condensation is still an issue.
[email protected]
 
Mold from condensation is a pain to deal with. However, there are quite a number of ways to handle the humidity. I've even worked on a project to produce water & area heating via adsorption of humidity. I've used several methods to control humidity (houses & apartments for now).

Venting is tried & true--in the case of yurts with an interior shower during winter, this would probably require a dedicated vent (ie, fan+ductwork out the crown ring, side, or out through the platform), potentially run on a timer switch. Fans are available for most any voltage/cfm rating (12 to 120 V, ac or dc; 10-1000 cfm) to match your power system (see sofasco.com or an electronics supplier such as newark.com). Spec'ing the fan cfm to exchange your room volume several times per hour is advisable.

Another option is damprid, as mentioned. I believe this is just Calcium Chloride flakes (a salt that absorbs water; can also be used to lower freezing temp of water/melt ice). I use it in my apartment that has no vent fans in the bathroom/kitchen. It absorbs several times its weight and turns into a puddle of salt water. Damprid is expensive and would require frequent replacing if used to control humidity from showers/clothes drying. I haven't tried using the bulk calcium chloride yet.

Another option is Drierite/Calcium Sulphate. It absorbs some of its weight in water. It can be baked at high temps in an oven to be renewed. Fancy types have a color indicator so you can see when it needs renewing. Moderate initial price, and you still have to vent the humidity released in the oven outside or it will just stick around.

There is also Zeolite/Molecular sieve (similar to Drierite in adsorption capacity & renewal methodology). Sometimes used to dry commercial gases. Absorbs ~15-20% water by zeolite mass.

All these could be used to control humidity--the salts/zeolite methods would still be best with a small fan circulating air over them. Figuring out where your moisture is coming from in the first place (propane stove/heater, shower, kitchen) and minimizing/controlling it there is still the best bet.
 
wow. yes. I totally relate. We get the instant frost, ice dams, and rain. Great description. And...our humidity is only at 32-35%. I've never seen it above 42%, and that's rare.
 
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