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 Solid Wall Yurt, Part Two

This is the second article on building a solid wall yurt. 

Although yurts both are vastly lighter in weight than conventional housing and offer minimal wind resistance, they, like any house, still require solid piles on which to rest. 

There are a number of options available to provide a solid base for your yurt, with the simplest and most solid being beams on pad, with no posts and no piles. 

When you opt to construct a solid wall yurt, rather than tarpaulin and lattice, you add significant weight to the structure, but, through the use of innovative top and bottom plates, cable reinforcement, hurricane ties and mending plates on the walls, you can build a yurt that equals any house for structural integrity.

To design a base system for a yurt by boring piles is an illustration of overkill, however.  Not only do you change the definition of your building for zoning and permitting purposes, you provide a degree of reinforcement that is quite unnecessary.

The most cost effective and structurally sound combination of bases for your yurt is a simple pad system.  However, you may, depending upon the grade and type of soil, need to use posts and pads, notched pads, crossties and webbing, saddle brackets and so on.

Let us look at the most simple design: beam on pad.  Whereas conventional wood frame homes may require 2 by 12, 2 by 10 or doubled versions of each for beams, imbedded joists, grade beams, piles, etc., yurts, even as large as forty-two feet in diameter, will require no more than single 2 by 10 or 2 by 8 beams under 2 by 8 or 2 by 6 joists. For flat terrain with packed soil and good drainage (or in high wind regions), use a basic patio pad.  For sloped ground, gravelly or soft soil or windy regions, use notched pads, or notched pads on patio pads secured with anchor bolts. 

Begin by ensuring that all pads are level with each other. Simply lay the beam into or onto the pad, and then tie the joists into position, sixteen inch on centre separation.  Beams should be spaced a minimum of eight feet apart, with pads spaced four feet apart for greatest stability.  Reinforce the beams by nailing cross supports between beams at eight foot separation.  As in conventional housing, joists should be tied together with webbing (2 by 2s).

To use post and pad on heights not exceeding twenty-four inches, use four by four double saddle brackets and double the beam using a second eighteen inch length of beam material in the upper saddle bracket.  Set the foot of your four by four pile into a slotted deck pad, ensuring that the top of each four by four posts is level versus each other post top.

To use post and pad systems on heights exceeding two feet, be sure to use diagonal cross supports extending from the bottom of each post to a nearby beam or joist on two adjacent sides, alternating sides with each sequential post location.

After laying the joists into place on the beams, be sure to install appropriate headers, using a minimum of four 3.5 inch nails per joist-to-header connection, and three nails, toe-nailed into place on each beam intersection.

Since you already have ensured that the structure is level (by levelling either the pads or the tops of the posts), you should only need to check level of the joists to ensure that nothing has shifted during construction.  Now, lay your underlay into place, using 2.5 inch nails.  The tongue-and-grove ¾ inch OSB or plywood should be placed so that edges meet at the centre of the joist.  Use plywood ties between joists for added structural strength.  Your next layer of flooring will be installed at right angles to the underlay, at a later time.