How Yurts Fall Down

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The best way to learn how things stay up is to learn how they fall down.

Side loads (wind) fall into two categories:

Implosion: The side wall is too high or roof pitch too steep; the yurt buckles in. The yurt may move as well if base is unsecured.

Explosion: The wind blows in through the open door and can lift up a yurt that is unsecured to ground. Or it disconnects rafters that are not fastened at both top and bottom. Traditional Asian nomadic yurts are not tied to the ground. And the rafters are not secured to resist tension at either top or bottom. But tradition dictates that they are never erected with the door pointing into the prevailing winds.

The hundreds of yurt modifications throughout thousands of years of Asian nomadic living have had to take into account the relative threats of wind vs. snow. Heavy snow load dictates a steep roof, but the wind on the steppes can be thwarted by a low-profile roof. This Minnesota yurt is both tall-walled and steep-roofed. It presented too much surface area to the wind. It imploded.

RAISING MISCALCULATION. Part way through the raising someone noticed that walls never got plumbed. . .

. . . so attempts were made to fix it, but with little success. The beauty of the yurt structure can be a liability: Once raised, it wants to stay that way. Wind will buffet it and snow will weigh it down, but the roundness pushes back. So these raisers had to backtrack.

A spiral failure is when the rafter-ring connections have insufficient lateral integrity. The ring 'spins' down. An inversion failure can occur when the rafter-ring connections have no vertical integrity. Uneven loading of the roof (think blizzard with snow loading only the leeward side) can cause the heavy side to buckle down while the opposite side rises to accommodate.

These two images show a 32-ft Imago yurt in Maine. Speculation is that uneven snow load caused a spiral failure. The joint between the rafter and roof ring was not designed to provide lateral resistance.

--In contrast, the homemade 25' rafter-ring joinery on the Connecticut Two Girls Yurt (below) looks pretty rugged.

Did the unbraced 2x6 rafters buckle sideways? A 2x6 is much less strong when sideways, so they need wooden blocking or wire to secure them. Sapling rafters do not have this problem

Was the roof ring constructed ruggedly enough?

Were the walls built strong enough to take the vertical load?

(where are the forensic experts when you need them??)

I don't remember the story behind this one. Looks like snow and an insufficient roof ring 'double-futtock'. This term comes from wooden boat building, when the timbers that form the hull's ribs are lapped from gunwale to gunwale. The yurt's roof ring should be made up of as few pieces as possible without compromising on grain direction. Eight pieces per futtock works well in a five-foot ring. I use a triple futtock when designing for a plumb cut on the the 2x6 rafter to muckle on to the ring. Then glue and screw! (note: Wiktionary says that 'muckle' is a regional term in Vermont and Maine. I can confirm its use in New Hampshire. Its meaning is clear, eh?)

Here's a central fluepipe on a 25' yurt that was connected incorrectly to the smokefree adapter at the skylight. When installing the upper (the uncrimped) end of the 6" fluepipe coming up from your stove:

1. Your fluepipe should slide over the adapter provided by 4”-8”. Too little and they can come apart when the yurt moves in the wind. Too much overlap and they may get stuck. To tell how much overlap you have, measure from the top of your fluepipe to the bottom of the black metal flange. There should be from 7" to 11" (see pic)

2. Your fluepipe should not be screwed to the adapter. It should be allowed to telescope up and down a little bit, allowing your yurt roof to shift with snow and wind without putting stress on the stove.

This 20' yurt was never tied to the platform. A 75 mph wind lifted it off. 'An explosion,' perhaps?

A random yurt failure from the internet. No information provided, but I'll warrant that a puff of wind released those rafter butt notches from their precarious perch on the tension cable. Not a snow-region yurt. Also wouldn't have been so dry inside with that square platform.

Imported modern Mongolian yurts are designed for a place with less moisture than New England. Their roof rings and skylights are a single piece which makes flashing nigh on impossible. Here's an attempt to remedy the situation.

These yurts had tension cable problems. In the left image, a 17' yurt was raised with a 14' yurt's tension cable (this was the fault of yours truly) The second owner of the yurt on the right let out the tension cable, causing the roof to settle. What was keeping it up? The chimney? Perhaps the wall fabrics?

Another random find from google image searching "yurt collapse." Snow? Mountains of Colorado. No sign of the lattice wall. What's that about?

A 14" poplar snapped off 40 feet up in the big Vermont blow of Dec 23, 2022. A rafter cracked so we swapped it out. No tears, fortunately. Remove large questionable trees beforehand!!

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