Yurt vapor barriers to combat mould

[Vagabondrobb]

Hello everyone, I've been reading threads on here for a while as a non member, so I'm delighted to join up and say hi! I'm Robb and I live in Sw Scotland - wet country.

We bought a traditional Mongolian last summer (polycotton outer layer, pvc roof/canvas walls, 15mm felt, cotton inner). Despite cleaning the inner wall canvas after last winter, it's absolutely ridden with mould right now and I'm fairly certain it's beyond help. The mould is mostly in the outer facing side, but the thick felt is absolutely saturated around its bottom end, so that's also contributing to the inner side getting a good dose too.

We live in difficult conditions for a yurt, so it's a matter of doing the best we can to keep

moisture

out.

I'm thinking of removing canvas, adding a layer of PVC around the walls and sealing to the the pvc roof layer, adding breathable

moisture

barrier on the inside, and then setting up an effective ventilation system to remove moisture from the air. Compared to a new canvas wall, all of this is very cheap to do and I won't have to worry about mould in the walls. However I'm a little bit worried about sealing the outer layer completely.

Has anyone done anything similar? I'm very open to ideas and suggestions from people who have been in a similar position/environment!!!

Many thanks in advance!

Robb

[TSRalex]

Originally Posted by Vagabondrobb

We live in difficult conditions for a yurt, so it's a matter of doing the best we can to keep moisture out.

Sorry to say (and maybe I´m wrong with my opinion.....), but I believe the decision for an traditional Yurt wasn´t the best for an climate as you have in GB....

It is not for nothing that modern yurts are built with high-tech materials and have many openings (windows & additional doors & partly ventilation flaps), which ensure good ventilation.

In traditional yurts there is the door and the

dome

where the air can circulate - in the lower areas of the side walls, the moisture can hardly get away and then settles on natural materials and has a good livelihood there.

But - just my 50 Cents....

[Bob Rowlands]

In a real wet climate I recommend you erect a heavy duty poly tarp above your yurt. Not on top of it, above it. Build a 'wall tent' frame over the yurt with 1" or 1.5" galvanized electrical tubing. The tubing is relatively cheap, as are the fittings used to join the frame sections. I have an 11x15 tarp set up in my back yard and have less than $600 in it, tarp, tubing, fittings, stakes and guy line cordage. It works GREAT to keep out the weather.

As for covers, if you can afford it, get a professionally made fifteen year cover. And yes, vent the yurt with operable windows and

dome

, if possible. Mold is BAD for your health. Good luck.

[Jafo]

Yurts have a tough time in wet areas, so I agree with Alex.

[Vagabondrobb]

Haha, with hindsight i tend the agree too, but unfortunately it's a little late for a modern yurt, at least in the foreseeable future. You live and learn!!

I like your pragmatism Bob, but we actually rent our yurt out for a good part of the year when we're not in it, and I think a big draw for people is the aesthetic experience. We also get a bit of wind too! The cover is a good idea! I will have to do some research.

Many thanks!

[Bob Rowlands]

I live in a semi arid climate in Colorado, with relatively little rain and snow. My 100% 17 oz. canvas yurt cover had small mildew spots all over it within three years of constant exposure to weather. It was factory treated with sunforger, but that doesn't hold up under non stop long term weather exposure. The cover was totally shot after five years and unliveable.

I took down the yurt, and built a 10x12 conventionally framed barn shed on the platform. Now as to poly tarp over wall tent frame, I erected that in June 2020, at the start of building the shed. It covered my saw and materials while building the shed. There was only a tarp covering the roof, not the walls.

The cover protected my cut area great. The shade was nice. That's the first time I ever worked outside under a tarped frame and it sold me on the benefits of a cover.

I took it down after a few months to take it hunting last fall, and erected a full coverage poly tarp over the frame and sides, and two other tarps, one on the front and one on the back. Superb hunt camp we were out 8 days.

I reerected a larger version, a fully covered 11x15 a few months ago out by the shed, and it's still up. All I can say is, if I had that kind of setup over my yurt, the cover would still be in great shape, since the sun and wet couldn't have gotten to it. If the tarp only lasted a year, big deal. They are cheap and a canvas yurt cover is definitely NOT cheap.

A poly tarp above the yurt roof, with no tarp extending to the ground, should suffice for protecting the yurt from getting soaked. Plus it wouldn't snap and pop in heavy wind. I'd think that would be a savior for a trad canvas covered yurt in your wet conditions. Soaked canvas/heavy mold IS gonna happen, it's cotton after all. So based on my limited experience, a poly cover over a wall tent frame is how I would roll. Good luck.

[HawaiiYurts]

Reflective

insulation

would likely be superior to any breathable

insulation

for preventing mold. Think Reflective, as that will reflect the heat back out and back the area between the insulation and exterior liner. Be sure to run the insulation past the perimeter floor, to the outside.

Is Paul with Red Kite Yurts still there in Scotland? Good folks!

[froit1]

Sealing the whole thing in PVC will make is worse.
Get rid of the PVC roof, cover the whole thing in vapor-open home-wrap, and then add a nice outer cover which is both breathing and leaking. Pure polyester flag-cloth if you can find it is best.
Trying to get rid of moisture through venting is a total wast of energy, and will not even be succesful.

[TSRalex]

Originally Posted by froit1

Trying to get rid of moisture through venting is a total wast of energy, and will not even be succesful.

OK - I see - all the test results from the past are wrong and the worldwide recommendations of specialists, for avoiding moisture with an intensive air venting, are given by stupids.

[froit1]

I also built a near-Passive House in the meantime, so I look at these problems with a more educated eye.

Venting will help, but it is near-impossible to totally vent the bottom side of the walls, where there is always furniture, and very little circulation, plus condensed moisture inside the felt trickling down. And it is a waste of energy, throwing all that energy-saturated moist air out, replacing it with new, cold air from outside. That new air, as it is warming up, will drop in relative moisture content, and that's what we like. But it is far from energy efficient. You are spending energy to get rid of moist, in stead of warming, there are better ways to do that.

And then some badly pitched yurts have capillary water being sucked up from a moist ground, but that is rally few, and relatively easy to fix by re-pitching, but better.