Planning to build a yurt in Czech Republic

[Knecht]

Still waiting for the khana laths. Should have them next week. I could work on the

center ring

meanwhile, but not sure if I should trust my math and make the

center ring

with roof pole slots count that my calculations are saying, or wait for the actual real count when the khana is done. Or perhaps I should rather work on the door frame?

[Bob Rowlands]

I'll review the math with you. If 9.2" lath centers, and with the lath crosses square when erected, divide the circumference by 26". The closest whole number is your rafter count.

The door frame is easy to build. I'd start building the ring right now especially if using hand tools. I highly recommend using power tools to build it, but power tools is how I roll. It's your call.

[Knecht]

Thanks, I'll finely measure the circumference first, as I think I've slightly slipped over the planned 6m diameter while building the deck.

Ok, I'll start working on the ring. Is there any ring size vs. yurt size rule I should follow? I was thinking 1m diameter for the ring.

[Bob Rowlands]

That'll work.

[Knecht]

So I've cut a 1/4 circle template out of osb leftover and checked my lumber supply (1m outer diameter and 90cm inner - is it enough? Should I have the ring wider? It's 10cm now, so about 4"). I have some nice 35mm thick short planks that are wide enough to provide four of the circle quarters. Have several more, but those are narrower and would only make 1/8s of the circle, but have enough material to make them half-to-half overlap each other at the joints, while the big 1/4s will be just touching, not overlaping. If I put together the 1/4s and overlay them with a layer of 1/8s, it will likely be sturdy enough, but also too thick and heavy and that's just one "stock" of the slotted ring!
I could find some thinner planks, but the thick ones would be really nice and I was saving them for this purpose for a while. Or should I make this thick ring and just drill holes into the edge, instead of slotting it? I'm a little worried about keeping the exact angle for the holes though, also worried about splitting the wood possibly and last, about joining the layers of the ring - even if I glue them together, I'd still like to put some wood screws through it. Not sure if the holes and screws could always avoid each other (if the screws are supposed to actualy connect the parts well).
Another way would be to make the 1/4s and connect them with a layer of plywood. But as soon as I buy plywood in such measure, I can just get thicker grade plywood and make the rings straight of it, as the Kama Yaminary plans say.
So, how about this? I don't want to give up using lumber rather than plywood, especially as I already have it for free (while having no plywood in that size), but also don't want to make my work tougher than it needs to be.

[Bob Rowlands]

Hand mortising 28 slots/holes into a 4" wide yurt ring, that's fabricated from a couple dozen framing drops festooned with hundreds of invisible screws, isn't on my bucket list.

However, if I had my standard carpentry work rig rolled out on your site, powered up and ready to rock and roll, and the Kaminari ring materials at hand, you'd have that ring ready for sand and paint after morning break.

[Knecht]

Ok, so I've started working on the ring. I'm using two layers of timber, 4 sections in one and 8 in the other. Planning to make holes into the edge and believe I won't need as many screws that it would make the drilling impossible.
Will see how it turns out.
Meanwhile, I came to a different issue: the edge of the roof tarp around the ring. I plan to put glass into the ring crown's sections (plus metal sheet with stove pipe hole in one) and seal the glass with silicone to make the center ring waterproof. I guess it will leak a bit, anyway, so I'll use the removable center cover (like you see on traditional yurts) in bad weather. My question is: what shall I do to hide the upper edge of the roof tarp under the ring somehow, so that rain wouldn't get under it when flowing from the glassed crown? I saw a Mongolian modern yurt pics with the crown glassed and that ring had a wide wooden overlap on it's edge, so I guess the roof tarp edge was hidden under it. Fine, but how am I supposed to get the hole in my roof tarp over this widened ring, yet make it tight enough around it then? Some sort of drawstring sewn into the edge?
I guess this issue must have been solved already, but can't find any details how people did it.

Also, I should get the khana laths in couple days. What would be good material for the tension band around it? Shall I make it really as a fabric strap (strong nylon webbing?), or rather use steel cable?

[Bob Rowlands]

On a 20' yurt I'd absolutely go with a 1/4" clad steel

tension cable

no question about it. Cut it two feet longer than the yurts circumference. Use 3 cable clamps to get it to the exact yurt circumference. Once you get the door frame attached to the wall, drop the cable in place atop the lath crosses -including across the top of door frame. #see note below# Once you stuff the rafters into their mortises that roof won't budge one bit in any type of weather, or under any type of roof load.

Note#
To my way of thinking, if the wall is basically the same height as the door frame, there's no reason to not run the cable all the way around the yurt, instead of anchoring it to either side of the door frame as they do in Mongolia. The walls on a Mongolian yurt are usually a foor or so lower than the door frame, and routing the cable up and over the door frame might be a problem. My yurt allows a continuous cable.

Can't advise on the crown since I've never made one.
Good luck.

[Knecht]

Thanks, I'll use cable then. So it shall be laid into the uppermost crossings of the khana laths, right? The roof laths will put some pressure on it and keep it there, ok?
As for setting the cable to the right length - do I understand it right, that I should build the wall+door frame, then take it's circumference measure, take the cable, make it into a loop using the clamps and then put it over the structure, right? Any reason why not to place the cable on the wall and clamp it there?

How about the Mongolians having the door higher than wall? How does it go along with the overall yurt shape, is the door frame protruding from the structure? I'll need to go through some photos, never noticed this detail.
This solution would actualy be good for me, as I'm just thinking about how low is my door gonna be. When planning my yurt, I was ok with 1,5m walls, as I knew I'll have furnite around them and will actualy live in the center area with more height. Somehow I didn't realize the door will be just as low.

[Bob Rowlands]

Yes, the cable will set in the lath cross saddle on a 1.5 meter high wall. I tie off every rafter-cable-lath cross junction with rope. It's imposible for the rafter notch to 'pop off' where it sets on the lath cross, or the cable to dislocate from the cross, regardless of weather.

You got the cable length correct. If it fully encircles the yurt, and passes on top of the door frame that is ~ wall height, the length is the yurt circumference. If the door frame is well above the wall height, you can anchor the cable to heavy duty screw eyes set in the door frame at lath cross height. Just do the math on correct cable length once you get your door frame built and the anchors installed and carabiners in hand. Math etc. of cable length done once things are built and measured in place..

Make loops in either end of the cable using cable clamps, and carabiner the cable loops to heavy duty screws eyes bolted through the frame front to back. If you proceed this way, make absolutely certain you have a bomb proof heavy duty KNOT FREE door frame that absolutely will not fail in a bad storm. In fact I'd use hardwood framing material under those circumstances.

BTW I joined the four corners of my door frame with metal tie brackets and screws, so it absolutely can not seperate under load.

As far as my door frame depth relative to the wall lath, I bolted my lath to the inward facing side of my 2X door frame. I built the frame with the 3.5" wide face of the stud facing to the outside. As a result, the frame stands proud of the wall lath by 1.5", the thickness of a 2x. The door is inset flush with the front of the door frame. An overlapping door is also possible. Up to you.

Lastly, make the door frame the heigth YOU want, and make everything else work around that. It certainly doesn't have to match the wall heigth. With a 1.5 m high wall, I would make the door frame a good 6"-12" taller, or tall enough you can wall in without stooping. It's up to you.