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.