Choosing Floor Insulation

[Zelig]

Yes, we get frost heaving and our frost depth is probably about 8ft or more. The charts for frost depth I've seen seem pretty broad-brush in nature.

Our "topography" over short distances has a range of 2-3 feet and the entire 26 acres might have a slope of 8-10 feet over the 1500-ish feet going toward the SSE.

I've been thinking earthbags, particularly because of the ability to use local soil and for the impermanence. We don't have a clear picture yet of how we want to develop the land and really just want to get set up there so we can spend all of our time there, learning its features, quirks and challenges.

I was under the impression that our climate is not cob-friendly, at least not as an exterior wall/foundation.

Another challenge we have is that our window of opportunity for working outdoors is pretty brief- June through September is about all we get and we have lots of permaculture projects that we want to deal with before focussing on a more permanent dwelling.

[hierony]

Have you considered using earthbags to make a slightly elevated level area, then using strawbales? Btw, the feedstores here charge 5 USD for a bale while the farmers charge ~$3 (sometimes including delivery). If you haven't already, might be worth checking craigslist/newspaper ads (fall is best time, of course).

Sounds like you'll have your work cut out for you--from what I've seen, permaculture takes some finesse to get a good system, but can be incredibly rewarding once setup. You'll have to post some pictures in the Simplicity/Everything Else categories :P

[Jay Aimes]

I found that 4" blue SM, cut to fit between the floor joists and up tight against the plywood floor, made a huge difference in how warm my floor stays. My first winter in the yurt was a challenge to say the least. First snow fall was late October and stayed until April.No

insulation

in floor and no skirt to close in the bottom. After the first storm under the platform completely drifted in with snow, which in turn put a real good frost on the floor inside. No fun. Second winter I piled hay bales around the perimeter to keep the snow out from underneath but the mice seemed to think I built them an apartment complex. After a mouse genocide, I got rid of the hay and scored some left over 4" blue SM from a job-site. Once the floor was completely insulated I sealed the critters out with old barn master roof metal screwed to the bottom of the joists. Then closed in the skirt with T&G 2x6 and used glass block on the south side to allow some sunshine to do its magic. Now with -28 C sustained for 3 weeks, I can still go barefoot. Floor is toasty warm. Plus the added bonus of the skirt keeping the snow drifts at bay. I found yurt living requires a severe learning curve. When I inquired about how much

insulation

I would need the answer was always the same. MORE.. Now I just need to figure out my water freezing issue and hopefully next winter I'll be living in the lap of luxury. Good Luck and remember to have fun. life's to short to sweat the small stuff.

[Bob Rowlands]

Good job Jay.

[Zelig]

Jay, what size and make of yurt do you have and what sort of wall and/or ceiling insulation?

[hierony]

Jay--did you really use hay bales? Mice would love the hay (seeds, green tasty legumes/grasses and all) much more than just straw (dry grass stalks). A search or two around also suggests if the straw isn't stacked tight together, mice like to borrow into it a lot more.

From your experience, it does sound like any floor insulation makes a world of difference! I'm a little surprised more yurt places don't put more emphasis on better insulation (floor & walls).

[kochevnik]

@Jay Aimes

Do you have a picture of your setup with SM? I am trying to picture it

[kochevnik]

Just bumping up the post.

I will be building a straw bale platform within the next couple of weeks and will keep you posted.

Thank you hierony for your help

[kochevnik]

Hello,

I am in the process of purchasing plywood for my platform. Can you tell me ideal thickness and also if pine is better or worse than fir?
One more question. How do you cut straw bales? Anything except chain saw?

Thank you

[Bob Rowlands]

Mice are part of a long biological chain of critters that can live under your yurt. Rabbits and mice are currently living under mine. And who knows what else. Very low deck and I can't see under it. I'm glad I did considering what lives under there now. lol

I'd use 3/4 T&G 'exterior rated' plywood. I absolutely would NOT use osb if there will be contact with damp organics other than wood framing and air exposure. I suggest you paint the side that faces down, towards the bales or framing, with two fat coats of cheap 'ooops' paint from Depot Lowes or wherever. That protects it very nicely.

That's what I did to the underside of my 2x6

yurt platform

decking. As an aside here I even painted the subfloor of my house to protect it during the build, since I framed it myself without a crew. It took a lot longer before it was dried in.

You can also caulk the gap for a bombproof seal. Use thin cheap caulk. If you really have no framing to anchor the plywood to, and it is essentially free floating atop the bales, I'd go two layers. Run the first layer, then the second perpendicular to the first and screw the two layers together. That will be solid as all git out, and keep ALL the critters out. 'Nothing' will come up through that floor.

Have fun building your place.