Plz critique my foam panel design aka hexayurt

alexgorbatchev · Post by **alexgorbatchev** » Tue Jul 15, 2014 2:52 pm

Hey friends!

This is my first time trying to design and build a hexayurt. I've done a bit of research and am leaning towards more simple design than traditional hexayurt. I found http://www.elkinsdiy.com/stationary-she ... d-shelter/ design to be the most simple yet provide ample space for 2 people.

Last night I started prototyping and came up with this variant (attached). The prototype is made out of 6 8x4 panels to scale. I'm planing to use khinges (http://rotordesign.com/bm/category/yurt/page/4/).

Please help me out with some feedback! Thank you!

FossaFerox · Post by **FossaFerox** » Tue Jul 15, 2014 3:56 pm

I foresee quite a few problems, though I'll wait till I leave the lab before I take a hard look at it. I will say this, it will require extensive guy lines. Seriously extensive. And with a flat roof and such steep walls attaching those guy lines is going to be a problem.

FossaFerox · Post by **FossaFerox** » Tue Jul 15, 2014 7:11 pm

Okay, setting aside the guyline problems for a second there are two big issues with the design. First, I feel the need to point out that you shouldn't call your structure a hexayurt. A hexayurt is six sided. It's a hexagonal yurt. Hexayurt. Make sense? If you aren't familiar with one, go look on Google Images, because I'm going to be describing how a hexayurt deals with several issues in comparison with how yours would.

The first problem is the height compared to the depth opposite that face (called the base of support). Assuming the structure is properly built and no joints are loaded to the point of failure (a big assumption with yours, more on this later) a yurt is rigid. For it to deform or change shape, it has already failed, so when examining/predicting anchor failures (far more likely) we can simplify the problem by limiting the options to your structuring sliding or tipping. Now, in reality neither one of these happens by itself. And for the sake of clarity, what tipping would actually look like is the front edge closest to the wind (windward) lifting up, effectively rotating around the side (or in your case, point) on the far side of the yurt.

A normal hexayurt is very deep compared to the size of a given face. This makes it very stable. It's the difference between trying to knock over a book case and trying to upend a coffee table of equal weight. This means that the wind is able to generate very little torque around our imaginary pivot, which means the downward force that the guylines on the windward side need to apply is minimal, bordering on nonexistant.

The sliding force is still an issue, but the lack of a pressing need to apply a downward force allows you to have very shallow guylines which will take care of that horizontal load no problem.

This isn't the case with yours. Your structure is inherently less stable and when a lateral load is applied you're going to be fighting to keep it from blowing away and from the front edge lifting up. The tension on your guylines will be much, much higher and they will be far more likely to pull out, at which point goodbye yurt.

Another major issue is how a loaded panel transfers force internally. You never want to "pull" on the edge of a panel or apply too much of a lateral load, it will snap. Imagine drilling a small hole in a panel, threading a rope through it, tying a stopper knot, and pulling on the rope. Bad things happen. Instead, you want panels to be pushed together and ultimately push against the anchors (typically an immobile hoop or loop of webbing) on the far side.

To transfer load from panel to panel you want the angle to be very large, greater than 90 degrees. On a normal hexayurt pushing on one panel transfers load to the two adjacent panels and the roof section above it very efficiently while effectively putting the entire panel into a state of compression. This compressive force helps counteract the "bending force" (your panel isn't going to bend appreciably, but it is still termed a bending force) since for a panel to snap it will happen on the inner edge which is in tension. Putting the entire panel into compression by squeezing it against it's neighbors helps alleviate this. In your design, by comparison, a panel can't safely or effectively transfer load to it's neighbors. The angle at the roof in particular is much too sharp.

The final problem is how you tie your guylines such that the panels opposite the wind are pushed into a net that's secured on the windward side. This is honestly the trickiest of the three problems and the one that jumped out at me immediately. Finding a way to tie the anchors that works is... a problem. A big problem, in fact, and one that I don't see a great answer to without custom fabbing a metal retainer that fits the roof section perfectly...

LowePro · Post by **LowePro** » Wed Jul 16, 2014 9:22 am

I'm not convinced this Teepee/tower is actually any simpler than the tried and true stretch-hexayurt. The tower/teepee description says it involves cutting beveled edges on the foam board, which is difficult or at least requires special tools, and the plywood triangle with wood block sills and flashing is not necessary on the typical yurt designs. Consider the 6' stretch-hexayurt if you're going for compact and simple for 2 people. Looks like an easier design/build. I like the K-hinge, curious how it stands up to the Playa. Will be telling my yurty camp mates about it.

watchyourfeet · Post by **watchyourfeet** » Wed Jul 16, 2014 12:31 pm

I'd say go for it and let us know how it works. As an engineer I've seen a lot of people on this board offering lengthy explanations of why an idea will or will not work without actually understanding the principals they're talking about. I'm not saying anyone is wrong here, just that you should take everything on Eplaya with a large grain of salt. Really the only person that's worth taking advice from is the guy who owns the blog you posted as he's the only one with any experience with these.

FossaFerox · Post by **FossaFerox** » Thu Jul 17, 2014 12:01 am

watchyourfeet wrote:I'd say go for it and let us know how it works. As an engineer I've seen a lot of people on this board offering lengthy explanations of why an idea will or will not work without actually understanding the principals they're talking about. I'm not saying anyone is wrong here, just that you should take everything on Eplaya with a large grain of salt. Really the only person that's worth taking advice from is the guy who owns the blog you posted as he's the only one with any experience with these.

Guess I'll ask UCLA if they'll refund my tuition and take my engineering degree back since apparently I don't understand statics.

Jovankat · Post by **Jovankat** » Thu Jul 17, 2014 1:22 am

FossaFerox wrote:
watchyourfeet wrote:I'd say go for it and let us know how it works. As an engineer I've seen a lot of people on this board offering lengthy explanations of why an idea will or will not work without actually understanding the principals they're talking about. I'm not saying anyone is wrong here, just that you should take everything on Eplaya with a large grain of salt. Really the only person that's worth taking advice from is the guy who owns the blog you posted as he's the only one with any experience with these.
Guess I'll ask UCLA if they'll refund my tuition and take my engineering degree back since apparently I don't understand statics.

Maybe you can use your Burning Man attendance as credit for prior learning and get your degree converted to an arts degree

BBadger · Post by **BBadger** » Thu Jul 17, 2014 2:02 am

watchyourfeet wrote:I'd say go for it and let us know how it works. As an engineer I've seen a lot of people on this board offering lengthy explanations of why an idea will or will not work without actually understanding the principals they're talking about. I'm not saying anyone is wrong here, just that you should take everything on Eplaya with a large grain of salt. Really the only person that's worth taking advice from is the guy who owns the blog you posted as he's the only one with any experience with these.

Please qualify your statements, because I've seen no evidence on your part that you've corrected, or for that matter can even identify, erroneous information provided here on the forum -- as an engineer or otherwise.

Post by **Sham** » Thu Jul 17, 2014 2:47 am

The main point that FessaFerox was making is that the 8 sided hexayurt is the perfect design for a structure that will stand up to wind. I have seen that the wind actually holds the structure in place when it pushes on the roof.

I'm not an engineer (nor do I play one on TV), but it seems that the design shown by the OP would collapse and blow away under any type of breeze or wind, where the hexayurt would have the best chance of staying intact.

FessaFerox offered up some great information that took years to learn. I would take that post very seriously and go with the more solid structure or you may find yourself roaming the playa searching for your clothes and belongings.

GreyCoyote · Post by **GreyCoyote** » Thu Jul 17, 2014 4:59 am

FossaFerox wrote:
Guess I'll ask UCLA if they'll refund my tuition and take my engineering degree back since apparently I don't understand statics.

Not to worry, Fossa. There is always a place for you at Texas A&M. (-ducking!-)

Old joke from the engineering community:
Q: Do you know the difference between a beaver and an Aggie?
A: A beaver knows how to stack wood...

watchyourfeet · Post by **watchyourfeet** » Thu Jul 17, 2014 8:11 am

FossaFerox wrote:
watchyourfeet wrote:I'd say go for it and let us know how it works. As an engineer I've seen a lot of people on this board offering lengthy explanations of why an idea will or will not work without actually understanding the principals they're talking about. I'm not saying anyone is wrong here, just that you should take everything on Eplaya with a large grain of salt. Really the only person that's worth taking advice from is the guy who owns the blog you posted as he's the only one with any experience with these.
Guess I'll ask UCLA if they'll refund my tuition and take my engineering degree back since apparently I don't understand statics.

I wasn't targeting your comment at all, I was just warning him that people on here have a tendency to poo-poo any idea they haven't seen before whether it makes sense or not. For example rather than offering advice, people will say things like "Well don't expect to sleep in my RV when your structure falls apart". I didn't even have the time to read through your analysis when I first saw this post but I'm sure it's fine. Sorry if it came off like I was responding to your comment. I realize I said the "lengthy explanation part" which would imply that, but I was merely trying to encourage him to try new ideas..

watchyourfeet · Post by **watchyourfeet** » Thu Jul 17, 2014 8:56 am

alexgorbatchev wrote:Hey friends!

This is my first time trying to design and build a hexayurt. I've done a bit of research and am leaning towards more simple design than traditional hexayurt. I found http://www.elkinsdiy.com/stationary-she ... d-shelter/ design to be the most simple yet provide ample space for 2 people.

Last night I started prototyping and came up with this variant (attached). The prototype is made out of 6 8x4 panels to scale. I'm planing to use khinges (http://rotordesign.com/bm/category/yurt/page/4/).

Please help me out with some feedback! Thank you!

Do you plan to build the roof panel out of plywood like he does in the link you provided? If so installing anchor points will be simple, but make sure you heavily reinforce the back of the board where your bolts go through. If you use a foam roof, a 3-way tape anchor may work as long as as you keep all three guy lines equally tensioned. The nice thing about this design is if the wind hits one of the flat faces the force will be transferred to the corner on the opposite side, resulting in a shear force in the two panels making up the corner. R-max panels are much stronger in shear than compression or bending, so this is a good thing. As for resisting tipping, that will be difficult, especially when the wind hits the corner. Long rebar and ratchet straps will hold it down, but may compress your panels too much, at which point you have to worry about bending again. My suggestion would be to put a 2x4 reinforcing strut down the center of each flat face (on the inside), connected to a plywood roof. Run rebar in at least two feet deep, ~4 feet out from the center of each flat face. Anchor to your plywood roof and ratchet the fuck out of those things. Or depending on playa conditions this year you may want two rebar stakes for each face, slightly off center. My 2 cents.

Edit: Another issue with the anchoring system on a hut of this shape is your guy lines will block access to the three faces, which would be the only option for locating a door. You could run the guy lines along the corners, but that wouldn't be ideal either because then when the wind hits a face you will have a very wide angle of tension between the two anchors. So you might have to get creative with the door.

Post by **Elderberry** » Thu Jul 17, 2014 11:07 pm

FossaFerox wrote:
watchyourfeet wrote:I'd say go for it and let us know how it works. As an engineer I've seen a lot of people on this board offering lengthy explanations of why an idea will or will not work without actually understanding the principals they're talking about. I'm not saying anyone is wrong here, just that you should take everything on Eplaya with a large grain of salt. Really the only person that's worth taking advice from is the guy who owns the blog you posted as he's the only one with any experience with these.
Guess I'll ask UCLA if they'll refund my tuition and take my engineering degree back since apparently I don't understand statics.

So I have a question for you. If two or more yurts were attached (i.e. setup with adjacent sides touching), how does that effect your equation?

alexgorbatchev · Post by **alexgorbatchev** » Thu Feb 23, 2017 2:57 pm

I wanted to follow up on my post. I've built the yurt and it has survived 3 burns now without any issues, including the monday rain storm 2 years ago. Here are some photos for your enjoyment

IMG_20160825_193829.jpg

IMG_20160825_190658.jpg

IMG_20160825_184744.jpg

watchyourfeet · Post by **watchyourfeet** » Thu Feb 23, 2017 4:17 pm

Great work! Way to go for it and try out a new idea. How did you end up anchoring it down?

alexgorbatchev · Post by **alexgorbatchev** » Thu Feb 23, 2017 4:19 pm

watchyourfeet wrote:Great work! Way to go for it and try out a new idea. How did you end up anchoring it down?

Four aluminum steaks on each corner about 3 feet away from the structure with paracord going across the roof. Works pretty well. The aluminum framing is supported by the wooden bracket in the roof, so essentially most of the stress falls on that, instead of the panels.

watchyourfeet · Post by **watchyourfeet** » Thu Feb 23, 2017 4:25 pm

alexgorbatchev wrote:
watchyourfeet wrote:Great work! Way to go for it and try out a new idea. How did you end up anchoring it down?
Four aluminum steaks on each corner about 3 feet away from the structure with paracord going across the roof. Works pretty well. The aluminum framing is supported by the wooden bracket in the roof, so essentially most of the stress falls on that, instead of the panels.

Did you have any issues with the flat faces flexing at the seams?

alexgorbatchev · Post by **alexgorbatchev** » Thu Feb 23, 2017 4:28 pm

watchyourfeet wrote:
alexgorbatchev wrote:
watchyourfeet wrote:Great work! Way to go for it and try out a new idea. How did you end up anchoring it down?
Four aluminum steaks on each corner about 3 feet away from the structure with paracord going across the roof. Works pretty well. The aluminum framing is supported by the wooden bracket in the roof, so essentially most of the stress falls on that, instead of the panels.
Did you have any issues with the flat faces flexing at the seams?

They did flex with strong wind gusts, but no issues other than some noise. First year I ended up taping up all seams from the inside with 6" painters tape, which made the whole thing near dust free... last two years I didn't bother, so there was some dust inside. At night, with a flashlight, you can literally see the stream of dust in the air moving up and out through the vent, it's pretty cool.

watchyourfeet · Post by **watchyourfeet** » Fri Feb 24, 2017 9:12 am

It's pretty amazing what you can built out there from foam panels if you think it through properly. Here's my creation:

We have three of them that have survived three years out there. I've had a handful of burners look at them and tell me they're doomed for failure but they are rock solid. The vertical faces are reinforced and the top and sides are all in compression so I can really ratchet the fuck out of those things.

alexgorbatchev · Post by **alexgorbatchev** » Fri Feb 24, 2017 9:42 am

Very cool! How well do they stack when flat? How did you reinforce the vertical panels?

watchyourfeet · Post by **watchyourfeet** » Fri Feb 24, 2017 10:34 am

alexgorbatchev wrote:Very cool! How well do they stack when flat? How did you reinforce the vertical panels?

They fold down flat with 9 panels in 3 sections (2 2-panel sections and one 5-panel section). The back wall is reinforced with a 1"x3" wood strut across the middle bolted to the panel with a big washer. The front (which you can't see) has two wood struts, one above the door and one below.

maladroit · Post by **maladroit** » Fri Feb 24, 2017 5:35 pm

Now you're making my plain old normal hexayurt look unexciting. That's just how cool Burning Man is, you can live in a space-foil hexagonal prism-home and still feel like the boring old non-adventurous type.

FlyingMonkey · Post by **FlyingMonkey** » Fri Feb 24, 2017 11:05 pm

[quote="alexgorbatchev"]I wanted to follow up on my post. I've built the yurt and it has survived 3 burns now without any issues, including the monday rain storm 2 years ago. Here are some photos for your enjoyment

quote]

Despite initial constructive criticism you actually went ahead with your design & built something pretty damn cool that works great.

Nice job.

How many revisions of your original plan did it take to get it right or is this one of those projects that continually evolves?
What are the worst winds it had to endure? I sat last year out but I know we had some strong winds in 2015.

Plz critique my foam panel design aka hexayurt

Plz critique my foam panel design aka hexayurt

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Re: Plz critique my foam panel design aka hexayurt

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Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

Re: Plz critique my foam panel design aka hexayurt

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Re: Plz critique my foam panel design aka hexayurt

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