Would this insulation idea work?

[BecomingArt]

Hi everyone,

We are trying to finish up our yurt for winter so we can move in and I'm wondering if this will work for the insulation-
I want to get 1/8" thick wool pad from The Felt Co. Eco-Felt, 1/8" Thick x 60" Wide - The Felt Company

and also get a layer of the double sided reflectix

It would go in order: Lattice, Wool Felt, Reflectix, Canvas

Will this be breathable enough? Also is there any issue putting the reflectix next to the canvas and it getting wet and not drying? I really want to avoid mold at all costs.

Thanks!

[hierony]

To be blunt & honest, who knows if it will be enough? You will find out this winter.

You can make some predictions of heat losses (various calculators online for standard construction, plus some that just take wall/roof/door/etc surface areas, temp differences, and

insulation

values), if you're one to crunch numbers. Otherwise know that my 20 ft yurt is *predicted* to lose 8k btu/hr (conduction) plus 3k btu/hr (infiltration/air changes) with an R-value of 7 & strawbales under the platform & 65 F temp difference. I'm hoping this works out but have a few backup plans if things get too cold (adding layers of

insulation

, sealing things up even more, supplementing

heating

as needed). Other forum posts indicate I'm being very optimistic.

I moved into my yurt about two months ago--there's been a few somewhat cold, rainy, and/or windy days where I wish the yurt was at least better sealed up against drafts and maybe had a bit more insulation. But drafts steal sooo much heat and I haven't fixed my draft problems yet.

You haven't mentioned what type of canvas you have (vinyl/treated, plan, or other). The foil insulation won't breath at all, unless you get inventive with poking holes in it (kind of counter productive...).

Recommended air change over rates for residences are 1-2 complete swaps of air per hour. Except in high temps & humidity (ie, summer sometimes), this should generally keep the humidity (and thereby mold) down. 1-2 ach in my yurt works out to ~40-80 cfm--basically a 5 watt computer fan running constantly (120 W*hr/day, or 3.6 kw*hr/month, or 32 cents/month).

Get a temp & humidity monitor and keep an eye on it--if the inside dewpoint is higher than the outside temp, you risk condensation & mold/mildew.

Best of luck!

[Aaron Harris]

Hello!

I'm thinking very similar to you, possibly because I read your post.

Humid air must be stopped from filtering through to the colder outer layers. So, while it would be nice to see interior felt, probably the best solution is to put the felt layers on the outside, the reflectix toward the inside, if you can seal it, and if not, a vapor barrier.

[Aaron Harris]

I'm leaning towards eschewing aesthetics and filling the space between rafters and snow load supports with loose wool insulation for about $3 per cubic foot: R20+ for $1800 plus freight.

I still want a layer of 1/8" felt as a friction buffer between canvas and rafters, but weighting whether it's worth it. I'll apply a reflective vapor barrier on the inside surface of the rafters and supports to keep humid air out of the walls.

[Jafo]

Just keep in mind, all that insulation is going to cause

moisture

issues unless you directly address that.

Moisture

= mold.

[hierony]

Using normal insulation is probably a good bet, and if you fill the wall crevices completely will likely cut down drafts some, too. The flip side of that is if you seal everything up, there will be no exits for air moisture (as Jafo suggested). But I think we've pointed this out several times already :P

I like your thinking for your layering. The insulation fibers may migrate a little--have you ever installed insulation before and felt the heavy fibers in the air? I'm mildly sensitive to the fiberglass insulation and get a little rash where it contacts my skin. With standard framing construction, the insulation gets nicely sealed in the walls and the occupants don't have to worry about it (until renovations, that is). With a reflective vapor barrier on the inside and a felt layer on the other side of the insulation with the cover on the very outside, you should be in pretty good shape. Except you'll have a very shiny/reflective interior--don't play with lasers inside your yurt :P

[Aaron Harris]

Originally Posted by hierony

Using normal insulation is probably a good bet, and if you fill the wall crevices completely will likely cut down drafts some, too. The flip side of that is if you seal everything up, there will be no exits for air moisture (as Jafo suggested). But I think we've pointed this out several times already :P

I like your thinking for your layering. The insulation fibers may migrate a little--have you ever installed insulation before and felt the heavy fibers in the air? I'm mildly sensitive to the fiberglass insulation and get a little rash where it contacts my skin. With standard framing construction, the insulation gets nicely sealed in the walls and the occupants don't have to worry about it (until renovations, that is). With a reflective vapor barrier on the inside and a felt layer on the other side of the insulation with the cover on the very outside, you should be in pretty good shape. Except you'll have a very shiny/reflective interior--don't play with lasers inside your yurt :P

Thanks, Hierony.

I'm pulling the trigger today on purchases. The loose insulation will be loose wool at $3 a cubic foot (600 cubic feet), borate-treated. I'll have an option for the white side or shiny side of reflective bubble(c)rap. to seal everything up... leaning towards white side, but would love to see an actual experiment to show me it's worth it... and ripping 2x4s for strips along studs and rafters where bubblecrap overlaps and seals.

I would *LOVE* a layer of felt between the rafter rub points and tech fabric, but at $1000... maybe just squares of carpet padding for now. I'll build it so I can access every 6th rafter space if I feel like feeding more layers up above.

R20+ and quite a bit less than the $3400 for the bubblewrap liner.

[Wintergreen282]

Keep us posted Aaron. Though I wonder how much really translates from one yurt to another. Just too many factors in play: temps and humidity in your area, yurt open or shaded by lots of trees, hours of sunshine, square footage per person, how much moisture you are adding, your air flow exchange rate, how much you run your stove and how big it is, how dry is your wood, and probably a dozen other factors. Love living in my yurt, but they are way closer to tents than a "stick and brick" house.

[Flea]

I know it's a bit of a necro post, but I like the idea of canvas, radiant barrier, and wool and is exactly what I thought about doing when I build my yurt. I saw a video on YouTube where someone had done this already and said it was a great combination.

I would recommend against Reflectix, as it's very cheap and flimsy. I have heard good things about Radiant Guard and they also make a breathable barrier that should take care of moisture concerns.

[Bob Rowlands]

Mongolian families have lived in wood, canvas, and felt yurts for many centuries.