The cover should be made from waterproof canvas. 12oz waterproof flame retardant cotton is the best. If you use new waterproof canvas it will cost about £100 for the cover, flame retardant finish will add another £30. Each yurt frame is unique in size and shape so it is not possible to make the cover to a pre-made pattern. When the frame is finished put it up in the garden (when there is little risk of rain) and make your cover to fit it. Ideally an industrial sewing machine should be used to sew the heavy canvas. But if this is not available a perfectly adequate job can be done with an old Singer hand sewing machine (available from most car boot sales or auctions for about £10), using strong polyester thread. It will take about two and a half working days to make the complete cover.
The canvas will shrink slightly when it first gets wet so allow an overlap of at least eight inches (20cm) between the roof and walls and make the walls at least three feet longer than the circumference of the frame (minus door). Alternatively pre-shrink the canvas.
The cover is made in four sections:
Put up the yurt frame and measure the height and the circumference of the walls, excluding the door. Make the cover the same height as the wall and three feet longer. Sew two widths of canvas together (for this size yurt you will probably use one and a quarter widths of the roll) use a double seam. The top sheet should overlap on the outside of the bottom one by about an inch so that rain runs off easily. Make a good 1½ inch (38mm) hem at the top and at each end. It is a good idea to sew a 6-8 inch (15-20cm) wide length of plastic around the bottom of the wall, overlap it about an inch (25mm) and sew it on the inside so that water is not directed into the yurt. Fit brass grommets into the top and end hems of the wall at spacings equal to the distance between two crossovers at the top of the khana. Tie a short string loop through each of the top grommets which will fit very loosely over the top of one wall pole. Tie a three foot (1m) length of string to each of the end grommets.>
Figure 9. Arrangement of canvas sheets for the roof cover.
Before you start work on the roof make sure you have plenty of space, thread, spare needles, and good quality dressmaking pins. Put up the yurt frame and set up your sewing machine in a large space next to it.
With reference to figure 6 lay a length of canvas over the frame and position as sheet A on the diagram, allow at least a foot overlap at each end. Pin sheets B and C securely into position and mark points X. Take these three sheets off and sew them together with a one inch overlap and a double seam, do not sew beyond point X. Ensure that the top sheet always overlaps the lower one to allow water to run off.
Place sheet A,B,C back onto the frame and pin sheet D into position. Mark points X. Take the cover off and sew the first seam, then cut from points Y to Z, leaving a flap of 1½ (38mm) inches. Fold the cut edge inside and sew the second seam. Do not sew beyond point X. Place the partly made cover back on the frame and continue adding sheets in the same way.
When all of the sheets are sewn together fit this cover and mark the position of the crown opening. Cut out this opening and sew strong webbing around the inner edge of the circle.
Finally fold, tuck and cut the ends of the sheets to hang down and overlap the walls by at least eight inches (20cm) (less above the door). sew a 1½ inch (38mm) hem around the bottom and fit a pair of brass grommets three inches (75mm) apart every three feet (1m).
The Crown cover
Make a three or four pointed canvas star, the centre of which is large enough to amply cover the crown. Put one or two tucks in the central part to give a convex profile to fit over the raised crown middle. attach five foot (1.5m) lengths of string to each point. It is easy to sew four triangular, or two semi-circular clear plastic windows into this cover if desired (Fig. 10).
The Tension band
This is a band which passes around the top of the khana and the ends of the roof poles to hold them in place, protect the roof cover from abrasion and as an additional safeguard against the weight of the roof pushing the walls outwards.
Take a piece of canvas as long as the wall and eight inches (20cm) wide. Sew a strong hem along either side of its length and a 1½ inch (38mm) hem at each end. Fit two brass grommets at either end, one in each corner. At each end tie a 10 inch (25cm) piece of rope between the two grommets to form a loop. Tie a three foot (1m) length of rope to each loop.
Figure 10. Three designs of crown cover.