Planning a forty foot yurt, check out my CAD design!

[EGEW]

Hello All!
My name is Evan, I've been lurking about on the forum for a few weeks now. I finally registered today and figured I would share what I've been planning and seek help/guidance from y'all. Please feel free to provide any advice!

I'm in colorado, I am yet to acquire land for the yurt, but it will probably be in colorado, or somewhere with similar heavy snow loads. I have two years left on my current apartment lease. I'm planning on building the whole the thing... slowly. Many trips to home-depot are in my future.

What I'm pretty sure about:
40 foot diameter
~7 ft walls
Larger toono, more windows.

lots more to type, will do so in follow ups. lets see if I can get some images attached....

 

[hierony]

Impressive! That will be one giant of a yurt--I hope you don't plan on moving it often

My yurt is nice & drafty (for the moment)--I would hate to heat a very drafty 1300 sq ft...

I'd also suggest being very careful about your membrane materials. Natural cotton is nice for breathability, but can wick moisture inwards if you're melting the snow off--it'll also degrade over 5 or so years. You'll probably use more modern material though. Also think about getting your canvas up there: the cotton canvas for my 20 ft yurt weighs 100-120 lbs, yours will be substantially heavier. Sewing it together will be quite the chore.

You're obviously thinking about snow loads--I like your four center columns. Any idea if you're 2x4 wall supports will need bracing to prevent buckling? I'd also be curious about the footing load.

With as much materials as you'd be using, it might be worth finding the local mill and getting a bundle or two of what you need direct. At least I've seen it done in my area.

Ask lots of questions & post lots of pics. Good luck!

 

[EGEW]

part2

Since I have time on my side, I'll be updating this design and posting here as I do so. And i'll be explaining why!

I would probably just buy a 40 ft yurt... but they are just a bit out of my price range..... like 20k more than I am wanting to spend.

Cost is the #1 reason why.
Reason #2 is that I can! and I can go at it at a snails pace. perfect!

The Khana I will make from 2"x4"x10' that will be cut into 4 pieces.

I may use 2'x6'x10' or 2x8x10''.... reasons why are actually worth noting for anyone else looking to DIY a Khana

we all know, the less knots the better. Wider boards may provide that more readily. Ill be cutting some boards down soon and let you know what I find(ill be buying home depot douglas fir)

perhaps someone already knows... Is wider better in this specific case?

The other reason is a numbers game. A 2x4 is actually 1.5x3.5'' if you cut 4 lengthwise pieces you will have 4 pieces of 1.5x(3.5/4) .875" or 7/8th" probably actually a little bit less from what the blade takes away.

now if you do the math for a "2x6" or a "2x8" or "2x10" you will find!

2x6 = 1.5x5.5 cut into 5 pieces 5.5/6 = 0.916'' aka 11/12th
2x10=1.5x9.5 cut into 10 pieces 9.5/10 = 0.95'' aka 95/100ths (I guess you could say) way more than the .875 from the "2x4"

So the point is using wider boards will yeild slightly thicker khana boards...

doesnt seem like much to us but if you using the metrix system
a 2x10 would yield you a 24.13mm thick khana board
a 2x4 yields a 22.22mm

So again not a huge difference, but it could be worth nothing if your supporting your roof with the khana

will post more later

 

[EGEW]

Hey Hierony!

Thank you.

I'm no architect, and hopefully someone who is sees my idea and can let me know if 2x6 for the vertical supports will be enough, and if 2x6 for the rafters will be enough. yikes so much to worry about!

Im quite certain ill need to use 2x8 for the verticals and probably for the rafters as well.

I've asked some local contractors about sourcing wood. They say home depot or lowes (ugh big box stores, i actually kinda like/hate them) is pretty much it, unless you need some other fancy woods there are some lumbar yards a little further out of town (denver) . I have'nt search for lumbar mills though... hummm........

Its going to weigh a few tons... no doubt about that.

I'm not sure how i'm going to build the base yet. probably going to involve some concrete, a very strong platform And a lot of insulation. (and maybe a crawlspace/cellar)

Certainly not going to be moving it..... probably ever!.

I may even do a more modern insulation in the walls, since Ill have the support beams there. almost makes the khana unnecessary... but hey if a bear tries breaking in im sure the khana would slow him down.... a little.

 

[EGEW]

This is the video that sold me on making a fourty footer

https://www.youtube.com/watch?v=VuuIgQEMOlw

its a beautiful yurt made by shelter designs yurts. it has a very impressive supporting central beam. Im not sure what size roof rafters they use. i think they are 2x8.

The goal of my design is to cut the wood as little as possible.

with 8ft wall height I wont have to cut the 2"x6"x8' that will be supporting the roof rafters.

By using such a large toono @ 11.7ft the 16ft roof rafters will work great, and may only need to be cut on one side to fit against the verticle support 2x6.

Thinking about making the toono out of metal...... I'm not sure how im going to pull that off...... but i think it could be made lighter weight then one of wood and would last longer, and be stronger than wood.

Any thoughts on making a 12 foot metal toono please give me some food for thought.

 

[Bob Rowlands]

A yurt is a tent, and tents do not hold up to weather long term like houses do. JFWIW. My little 16'er has been up for about three and a half years, and the canvas cover needs replaced. It is shot.

A 40' yurt is incredibly immense, in comparison to a 30'er, a huge yurt. Remember as great as they are, yurts are not houses. They most definitely are tents. IMO you would be better off starting with a much smaller yurt, say a 24'er, and then adding another as time goes by. If you do end up with an immense 40' yurt, you may have trouble selling it if it ends up not being what you are hoping for. Just my opinions here. Personally I would never consider a yurt near that big, based on my experience with my 16'er.

 

[EGEW]

Hey Bob!

I certain see your point. Calling this a "yurt" is a bit misleading. This structure I am build is only going to have the shape of a yurt. By no means will it be portable, heck it would take a team of 40 yaks just to move the lumber.

What I am building is going to be a home for my budding family I'm shooting for something comparable the yurt in this video https://www.youtube.com/watch?v=VuuIgQEMOlw (same one linked in my last post)

I'm surprised your canvas cover is shot after 3.5 years. Is that typical?

I've done a bit of looking around for cover options. (heck I may use a corrugated metal roof)
Duro-Last says their material will last 15 years. And you can place an order with them directly to make your cover. they will do custom made to order covers. Sweet!

A huge part of building this yurt is going to be working with a permitting office, and getting their stamp of approval. This very well may impact my plans.

Also I don't have land yet, So its kinda hard for me to say for sure what kinda snow loads & insulation needs i'll have. Who knows were this new home will be built. Could be here in colorado, could be in the pacific north west! (bigfoot country, holler)

Question! is there any older threads showing a 40ft build? I love forums but these old forums wont search short terms like "40ft" the built in search engine rejects it. Also sorry for all the typo's........ I'm half lazy and half dyslexic, horrible combination to have.

Here are some pricing calculation for the roof and walls
roof rafters 2x6x16 72pc = currently about $10.50ea => $756 => round up for good measure => $850

Support beams 2x8x8 About $6.75 each 72 needed => $486 => round up=> $550

khana 186 x 1.5x0.75x10foot => 48 x 2x4x10 @ $3 each = $144 +> round up => $200

So rafters+support beams+khana $850+$550+200= $1600

pretty good! hopefully I can get away with using 2x6 for the rafters.... 2x8 would knock this price up a bit.... how much you ask well

2x8x16 are about $14 each => $1008 => round up to =>1150 for good measure

making the new total => 1150+550+200 = $1900

Still not that bad. Gotta love circles, most square footage for a given perimeter.

 

[EGEW]

I was previously wondering about making the Toono out of metal. Having a 12ft metal ring custom made, would be crazy expensive.

So I began searching the web for possible sources for a 12 ft metal ring to use for a toono or something of the like, a compression ring.

Came across 10 12 14 15 ft trampoline frames. these are easily acquired for little money. The canvas like stretchy mesh wears out after a few years and then people list the frames on craigslist all the time. Usually for less than $100.

I'm thinking about using two of them, one on top of the other serperated by a few inches. maybe notching the roof rafters to accept the metal trampoline frame. or attach the rafter to the trampoline frames with half round metal clamps, like conduit hold down.

Cad drawing coming for this trampoline ring/frame idea.

 

[hierony]

Building codes may be against you, especially in terms of insulation. I don't know the R-values off the top of my head, but at least 3.5" (2x4 depth) would likely be required.

One thing to keep in mind is lumber grades--stud standard or No 2 is pretty marginal (lots of knots & other imperfections), but the rated stuff can be darn nice (for what is available nowadays). I've only seen the rated stuff at the truss manufacturing plant where I worked during college, but the big box stores *might* have it. As a retired carpenter, Bob likely knows more about this though.

I would be very dubious about using trampoline frames for a crown ring--snow & wind loads get partially transferred to it, and with such a large yurt that would be a rather substantial force. The major problem detail would be the connections between crown ring pieces (strong welds?) and the amount/cross-sectional area of the material there (also roof pole-to-crown-ring). A geodesic dome of sorts may work, but that is something I'd suggest consulting an engineer about. The crown ring is the heart of the yurt--you really don't want it to fail.

Yes, plain cotton canvas degrades pretty quickly in sunlight; Colorado has pretty high UV exposure & I suspect Bob used lighter canvas than most yurts. But 3-5 years isn't bad for constant exposure of a natural fiber. The modern treated materials last a bit longer (15-30 years) according to the spec sheets, almost comparable to asphalt shingle roofs.

 

[Jafo]

I know Nomad Shelter yurts makes a 40 footer. You might want to check out their design. I am happy to see you will have center supports of some kind because I think that is wise with a larger yurt.

I would think 2X4 vertical supports would be just fine, but I would definitely go with the 2X6 on the rafters. I almost wonder how much cost difference there would be with LDL's? Probably a lot.

 

[Bob Rowlands]

I knew nothing about the longevity of 100% cotton canvas when I covered my yurt in June 2013. Now I do. The water repellent in this canvas was pretty much done after two years of constant weather exposure. I now know that is pretty good service. This canvas still has plenty of structural strength but it leaks like a sieve now. I'm considering painting it when we get a warm stretch of weather.

Wall tent maufacturers state their tents will last a lifetime, and that is true, IF you use the tent two weeks a year, you would get fifty years of service, based on my experience. Canvas is cloth and non stop weather exposure will take out the water repellency, and then the cloth, in probably about five years. Leave a pair of Carhartt work pants out for 3.5 years and see where they are after that time.

I now know that anyone considering a yurt as their primary residence should buy a fifteen year cover.

 

[EGEW]

Hey Jafo. wow nomad even makes a 50 ft yurt! Lots of planing ahoy. What are LDL? mentioned in your previous post?

Last night i spent some time comparing the prices for SIP flooring. Mostly comparing how much it would cost to DIY vs Manufactured.

For anyone interested premade SIP flooring that is r-25 6.5'' thick runs about $5/sqft. yikes over $6300

if I was to DIY it with home depot purchased materials...EPS foam..... $ a little over $4200.... wow... WOW

Expensive, mostly because of the EPS which is that white foamboards.

 

[Jafo]

Sorry, LVL

 

[EGEW]

oh LVL or Laminated veneer lumber

I had never heard of it. Guess I should have taken the Woodworking level 2 & 3 when I was in highschool.

Anyone wanting to learn more about LVL check out the wiki page on it, I did
https://en.wikipedia.org/wiki/Laminated_veneer_lumber

Its kinda like the 2x4 or dimensional lumber version of plywood. But made differently/better then plywood.

LVL is less prone to warping. shrinking. breaking. better for windloads, better all around. If you like things made better and cost isnt a factor.... LVL may be for you!

A company called Boise Cascade (for some reason I think they maybe in Idaho ) makes them and sells them at my local home depot.

2x4x8 are sold in boxes of three. They are about $15each.
2x4x8 #2 kiln dried studs are a bit under $3 each.

If you want a better yurt, its probably worth the expense


Jafo were you thinking of using them for vertical support or rafters (or both)? I could certainly see that the vertical supports are going to be bearing a continuous heavy load. I'm sure the structure would benefit from using LVL rafters too. could probably get away with using 2x4x16ft LVL for the rafters. According to Boise cascade their LVLs are 2.6x more load bearing or something like that.

Thank you Jafo for introducing LVLs to me and whoever maybe reading this in the future.

 

[Jafo]

I was thinking rafters.. The vertical support doesn't need to be crazy strong because all the force is on the end grain. LVL's strength comes on edge/side grain, at least as far as I understand.

I may be wrong, but I do think there is a significant weight difference in LVL versus standard. I believe it is heavier. That would have to be worked into your calculations.

 

[EGEW]

Back to the idea of using trampoline frame(s) for structural support. I've attached some images to help illustrate this idea. The notches in the rafters that would accept the tubular steel are angled backward&up, this would work with the compression forces to prevent the steel tube from falling out. also there is only a 4'' space between each rafter @ the toono.

the drawing would be using 3 tramp poles. a 12 footer a 14 footer and a 15 footer.

specs for sears trampoline
http://i.sears.com/s/d/pdf/mp-tc/spinpdf/spin_prod_980548112
18 gauge galvanized steel that is 1.5'' diameter
Tramps are usually rated for 1000lb on the net (jumpers up to 200lbs) im pretty sure you could have a few thousand pounds on a trampoline net before the frame would give out

I think this would certainly weaken the wood, having notches, especially three of them. I've seen people burn holes in a toono ring made of wood for each rafter (more traditional style) I was wondering if burning the material away helps to keep the structural integrity of the wood.

another thing to consider is lightening. have large metal rings at the top of a tall (16ft tall) yurt could attract lightening. I think you could ground them with a nice heavy gauge wire. or coat them in a PlastiDip coating.

Plastidip coating which is a rubberized spray on paint use on cars. I think could be safe for interior living areas. would'nt be terribly expensive and comes in many colors.


Im pretty sure LVL are going to be out of my budget. I found a company that does offer them
House Framing Lumber and Studs, Pricing
they have LVL of many sizes. priced per linear foot.
Closest thing they have to a 2x6 is a 1.75"x7.25" @ 3.33 lnFt making a 16ft unit $53.28! yikes. 72 pieces => $3836.00 wooooowzers!

 

[cdndenver]

Wow brother. I am so going to follow this. Me and some friends bought some land south of Colorado Springs. We are each going to build one smaller Yurt each and then one real large center social yurt. I really love what your talking about. You say Denver-ish. Would love to buy you a beer some time.

 

[EGEW]

cdndenver Thanks man! I'm glad to hear you like the work. I'm totally down to meet up sometime. you can send me a email at [email protected]

General update: I recovered a metal railing for a staircase that one of my neighbors threw in the trash.... or more so place near the trash. This thing would never fit into a dumpster. I think its about 20 ft long!

Its old, has some rust, its metal with a 2x6 wood beam running across the top (where your hand would contact the railing). I'm gonna have to spend some time on it, needs to be welded in a couple of spots.

An exciting find for me! I'll probably do a post in this thread covering the process of referbing it with pictures and such

 

[Snowbison]

Just a note #1 Vail resorts has 40ft yurts in Keystone and Vail. As far as your metal ring idea good for the weight. You can get a pipe bender at Harbor Freight or I'm sure there's a shop in Den. that has a pipe bender like a muffler shop. They will be able to weld it up for you too. Love the CAD work!!