Moisture in the Yurt from Condensation

[Heck Yeah Holler]

So if a person heated entirely with wood and had real windows to crack, had no running water (so no showers causing moisture!) but also had no electricity (off-grid means a dehumidifier running 24/7 would be an impossibility) would we ever be able to fend off this terrible condensation issue? I really, really don't want to have frozen domes and yurtcicles.

-30 F days are the norm for our winters.

[Kiwassa]

Burning wood really helps with the

moisture

. I didn't have an issue with

moisture

and -30 degrees were the norm for us last year too.

[Knecht]

Well looks like I've just joined the condensation club. For a long time there was no problem, but as temperatures are dropping lately and we have the woodstove lit most of the day, I've just found out there's lot of moisture on the inner side of the roof cover, that's soaking into the hemp felt we have under it. Not sure what to do. Our

dome

is made as fully closed and we have no windows. Guess we can keep the door open for some longer periods of time during the day, to let the air change. Other than that...I'm not sure. Dehumidifier might be an option. Spending less time in the yurt (less breathing and less

heating

time needed) would be another. What else?

[Jafo]

What about a vent pipe in the

dome

, perhaps with a cap?

[hierony]

Do you have electric power to your yurt? It might be easier to cut a small hole in your floor and connect a small fan (similar in size & noise to a computer fun) to force a small amount of ventilation outside. The other option might be to let your stove pull a little interior air (the makeup air would then be dry, cold outside air).

Your case puzzles me--all the other reports of yurt condensation have people living full time in the yurt, usually with water facilities and non-breathable covers. I don't recall all the details of your setup though...

[Knecht]

Yes, we have electric power. The fan might be a way to go, though I think there's some larger caliber solution needed. I was thinking about making several air-pipes of some sorts, that would go somewhere from roof ring along with the rafters and lead outside, under the roof cover skirt. Also, we had the roof skirt tied around tightly, to avoid insect invasion in the summer. Perhaps if I loosen it again, it would allow for both airflow and for some of the moisture to flow out.
We have a gap left over the door, just between the upper door edge and door frame top beam. It has screen to block instect coming to the light and lets some air in/out. The door itself isn't 100% airtight either, as the planks have dried up and that caused many gaps to appear. I planned to fill the gaps and repaint the door, but I guess I'll let it be now. We've moved to the house for a couple days and we let the yurt door open all day to allow as many of the moisture escape as possible, before we decide what to do.

[Bob Rowlands]

Yurts are sensitive to trapped moisture. IMO the cover needs to breathe. If the roof cover is impermeable, then the wall cover should be permeable. Add an operable window?

[hierony]

I suspect that when you're getting dew/frost on the ground outside, you'll probably get condensation inside. Any outside air you bring in will have the same dew point, and canvas doesn't insulate much (ie, it'll probably get close to the night time lows causing the dew outside).

I don't know about the weather in your area, but where I'm at in fall we get a fair bit of moisture in the outside air via rain. Our dewpoint is right about freezing, with lows about the same and highs ~40 F/5 C. The only way to prevent condensation this time of year here would be to dry the air inside the yurt (dessicants like zeolite/molecular sieve, calcium chloride, drierite/calcium sulfate; or use a dehumidifier; or outlandishly condensing it out of the air via freezing) and keep the yurt sealed up.

A house has a lot more thermal mass that keeps it warm through the night, plus the walls are usually moderately sealed up (the paint and the plaster/drywall on the interior, paint+wood siding+moisture barriers on the exterior). A yurt, on the other hand, has either fabric lining/insulation/walls which easily let moisture through. So unless the temp of all the yurt's layers is higher than the air's dew point, there'll be condensation.

I think this means either a hot fire all night or a dehumidifier

[Bob Rowlands]

I've noticed Mongolian yurts have walls lower than those here in the U.S. Less height, less volume=easier to heat. I understand it is dry in Mongolia, however just possibly the warmer it is inside the less likely condensation can be an issue. Just a guess.

[hierony]

Yep, the lower walls would mean less volume to heat and less surface are to loose it through. Mongolians are also a little bit shorter on average and don't seem to think it's terribly important to stand next to your walls with lots of headspace...

From the pictures I've seen and the bits I've read, Mongolian climate is different than most of N. America that I know of, similar though to continental climates (like Colorado). They have cold, dry winters with a little snow and get summer rains (4-15" or such). They get blizzards/zuds some years. Very unlike places with wet, cool springs/autumns.

To use the

heating

to prevent condensation, you'd have to get the outermost layer above the dew point consistently all night--not terribly easy. I've heard of a fellow that rolls up the yurt skirt a little and bakes the place out with his wood stove after any good fall/spring rains. If you see steam coming off, that's probably hot enough. That'd take some wood, though...