Making A Yurt Rafter Ring

One of the most basic components, yet one of the most crucial structural elements of any yurt is the rafter ring.  This device holds each rafter in place, ensures geometrical and structural integrity of the building, allows for installation of the essential dome vent and must be installed so as to apply uniform weight and pressure to each rafter at the same time that each rafter equally holds it in place.  There are a number of pieces that make up this assembly, whether it is designed and constructed  in-house or custom ordered.

The ring, in some instances, is built from one piece of wood.  However, this is quite a costly venture, relative to the total cost of the yurt.  Other wooden rings use a layered approach, sandwiching a layer of OSB between pieces of dimensional lumber, or the reverse. Other rings are constructed from metal, or metal and wood combinations, while a few are built of polymers.  Since most yurt-dwellers have a core of self-sufficiency, I recommend constructing the ring completely from dimensional lumber, in layers. 

For this piece of your modern Mongolian yurt, you will need fourteen eight-foot lengths of one by six spruce, fir or pine planks.  As well, one quart of carpenters glue and one hundred eighty two-inch construction screws complete your parts inventory.  For tools, you will need a variable speed drill, ½ inch drill bit, screwdriver bit, jig saw with blades and a small paint brush.

Begin by cutting all of the eight-foot lengths of planking into four-foot lengths.  Lay them side by side, using nine pieces on the first layer to form a near-square.  Due to the actual width of a six inch plank (5.5 inches) he total width should be 49.5 inches – slightly wider than the length.  At this point, this is not important.  Next, tie these boards together temporarily, using one of the four-foot lengths screwed across the centre point of the nine boards.  Apply a liberal coat of carpenters glue to the surface.

For the next layer, lay the second set of nine boards perpendicular to the first layer, with the leading edge flush with one side of the 49.5 inch width.  This will leave 1.5 inches of the first layer exposed.  Later, that surplus will be removed.  Put one screw at each end of the nine boards of the second layer.  Since there is no lateral security using single sets of screws, you now are able to square the assembly, using a standard two foot square.  Holding the setup in place, set one screw every six inches, alternating from one side of each board to the other.  The screws will protrude beyond the bottom side of the first layer at this time.

Flip the two layers over, applying a layer of carpenters glue to the underside of the first layer.  Lay the third layer of boards perpendicular to this first layer, and attach exactly as you did with the second layer.  Allow the assembly to dry, then use a saw to remove the 1.5 inches of excess width on the second layer.

Use two strings from alternate corners of the square, so that the two strings cross over precisely in the centre of the box.  Secure a nail here, then tie a string that is exactly the length of the distance between the centre and any side to the nail.  Be sure that the string or twine is not stretchy.  If necessary, use a thin piece of wire.  Hold a pencil at the very end of the string, and arc it around the outside of the square, drawing a perfect circle.  Now, shorten the string by eight inches, and draw a second circle.

Using your jig saw, cut the exterior run of the first circle.  Drill a hole at any point of the inner circle, then use your jigsaw o cut out the centre piece.  You have constructed your basic rafter ring.  However, for added reinforcement, you may want to screw a band of medium thickness aluminum ring around the circumference of the ring.  Alternatively, a ring of 3/16 inch plywood may be glued and screwed to the outer edge.

Building A Yurt In Winter

Building a yurt may not be at the top of your desirability rankings in the dead of winter, but, with proper planning, a quality structure can be pre-fabricated, then assembled on site in a matter of a few days.  While flexible-wall, tarpaulin yurts are the most popular structures in North America, it is the solid-wall yurt that provides the greatest protection, for the lowest cost in cooler and colder climates.  Soft-wall yurts offer the primary advantage of being able to be assembled, then disassembled and relocated with relat9ve we, while solid structures do not lend themselves well to relocation. The question then becomes, if you intend to relocate frequently, why not buy a tent or RV?

Our solid-wall yurt will stand for years, and has proven itself, already, to be a weather-tight, comfortable home.  Although, due to our wanderlust and travelling nature in winter, we do not spent the deepest Part of winter in our home, it has endured the coldest, snowiest and windiest days of our Manitoba, Canada winters.  If minus-40 is still too warm for you, then a yurt, of any variety, may not be a viable living solution! 

By using 2-foot panels, assembled on an 8-degree angle to each other, we have constructed a 600-square foot (that’s incorrect:  hard to have square feet in a round building!) facility.  Similarly, one could build a yurt in a variety of diameters (12, 16, 24, 32) with relative simplicity. 

Simply construct the individual panels, cut the sectional top and bottom plates, build the roof ring and saw the appropriate angles into the roof rafters, and the entire package of components is ready to be shipped to your building site.  Assembly on your pre-existing platform or floor should take two people no more than 12 hours.  Slide the wall tarpaulins around this wooden framework, slip the roof tarpaulin over the rafters and install your doors and windows and your yurt is ready for the finishing inside touches.

The tarpaulin walls offer both aesthetic and practical benefits.  As a Tyvek-type exterior skin, the tarp is impervious to the most violent winds, while repelling both rain and snow. The roof tarpaulin, however, needs to be installed tightly.  This demands that the supplier manufactures it to your precise dimensions and pitch, and that your roof rafters and top plate assembly are equally precise.  If the tarp is too loose, any flapping or vibration in the wind will act as a billows, and dislodge your roof fibreglass batt insulation, or break the seal on your foil-backed bubble insulation used to line the interior of the ceiling.

Within two days, your yurt metamorphoses from a pile of dimensional lumber and fabric in your garage to a fully liveable home, for less than 50% of the cost of a conventional  flexible-wall yurt, and one twelfth to 1/6 of the cost of s similarly-sized conventional house.  The added appeal is that this project can be undertaken and completed at any time of the year.

Yurt Exterior Skins

Our yurt is designed with two exterior tarpaulin skins. The inner layer is a commercially available tarpaulin skin, intended to provide a secondary protection against rainfall, and a buffer to reduce the amount of friction of edges of the structure against the heavy-duty uv-protected tarpaulin.
The tarpaulins were purchased from Cover-Tech (New Brunswick, Canada), who provided the lowest price quote for a 12 ounce tarpaulin.
The two pieces were custom made, with the wall tarpaulin being 94 feet long and 7’6” high. The extra length will be used to lap over the doorway when we are away for long periods of time. The height exceed the height of the wall structure by six inches, to allow for overlap at the top of the wall framing (under the roof tarp) and excess length at the bottom to allow for water runoff and reduce inflow of cold air in winter. The roof tarp, too, was ordered at 30 feet in diameter, while the yurt was built to 28 feet. The extra foot around the perimeter provides enough material for us to create a partial awning over the windows, to deflect rain and snow.
A small problem occurred with the roof tarp that was easily remedied. The roofline angle (slope) was calculated at 30 degrees. However, after seaming, the tarpaulin was sewn at a 33 degree angle, and our rafter cuts were out by 2 degrees. As well, while the tarp is manufactured as a circle (cone), the yurt actually consists of 44 straight-edge sections. This resulted in a loose fit of the tarp. Normally, this would be a severe problem, as the flutter of the tarp in moderate winds would exacerbate the degrading of the tarpaulin. However, our roof vent design allowed us to snug the tarp over the vent frame, and use only one tuck of material around the entire cone area.
Once the roof tarp was hoisted into place using pulleys and ropes, the wall tarp was erected, and the top edge snugged under the lower edge of the roof tarp. Using a series of ratchet tie-downs attached together, we tightened the straps around both the upper and lower perimeter of the wall tarps, holding the roof top securely against the wall tarp. To ensure that the roof tarp did not free itself from the tie-downs, polyester rope was threaded through the tarp eyelets, and the ratchet tie-downs fed through the rope loops.
Lastly, we cut three-sided openings in the wall tarp for the windows and doorway (the fourth upper side was left uncut), retaining the material to use as a roll-down sunshade.

Assembling the Yurt Walls

There is the easy way to build a yurt: seek out a quality supplier of yurt kits, select your options &size, and then make your purchase. There is a more difficult way to build a yurt: tour the yurt demonstrations of a variety of suppliers and build based on those model units. Then there is the road less travelled: design & build your own. This is the option my wife and I have chosen.
Conventional, commercial yurt walls are constructed using lattice wrapped with pvc tarpaulin material. A thin aircraft cable is interlaced in the top openings of the latticework, and tightened using a turnbuckle. This structure holds the walls inward in a circle, while the weight of the rafters resting on the cable pushes the walls outward. Stasis, strength and stability thus are achieved.
Our wall structure begins with a 2*3 framework installed around the inside perimeter of a 24” by 84” piece of 7/16” thick oriented strand board. Since our yurt is twenty-eight feet in diameter, with a circumference of approximately eighty-eight feet, 44 sections are needed. Each section meets the next at an eight degree angle, requiring that one of the two vertical 2” by 3” studs is cut with an eight degree taper.
To lay out the bottom plate, forty-four 2-foot lengths of 2 by 3 are cut in a slight “vee” shape, at an eight degree angle, as well. Each wall segment will meet the next at the point of the “vee,” with a one-foot extension extending into the adjacent section base. By fastening the wall to these bottom plate segments, a solid circular frame is created.
As each section is placed standing adjoining the next, a top plate, identical to the bottom plate segment, is secured along the top 2” by 3” horizontal piece of the wall.
After making sure that all wall segments are vertically plumb, metal joining plates are fastened to join the segments at the top and bottom of each wall segment.
Next, windows and the main door are framed in place, in the same manner as a conventional wall and door or window buck are installed.
For our yurt, we purchased the 7’6” high by 94’ long tarpaulin from a New Brunswick supplier. The fabric intentionally was ordered longer than the actual circumference of the yurt, to allow for gathering and darts around the doors and windows.
Prior to installing the tarpaulin around the perimeter, window and door edges are caulked and sealed. Along the bottom of the wall segments, a strip of Velcro is fastened. The tarpaulin will extend one inch below the bottom of the wall, so that water will run off and away from the floor. After wrapping the tarp around the yurt walls and temporarily holding it in place, six 15-foot long ratchet tie-downs are connected and tightened along the upper perimeter of the walls, permanently fixing the wall tarp into place.
Walls are now complete.
The next article will describe how to construct the roof rafters and install the assembly onto the yurt.