Question about cutting the inner liner (roof)?

[Bob Rowlands]

IMO green is gonna be one massive headache so I would not take that approach.

I made my outside yurt cover from a flat tarp I bought from mytarp, just like you are showing in purple diagram. I cut a rough hole about a foot in diameter in the center of the flat tarp, laid it on top of the rafters, hole in the center of the ring. Made a large fold in it so I got a conic fit of the tarp tight to the rafters. I marked that folded seam from inside the yurt with a sharpie. Allowed for lap fell seam and cut and sew. Reinstalled cover and it fit perfectly.

You could also bipass the folding technique and just cut to the center hole. Cut tarp on bias from edge up to hole. Roll that out atop the rafters, drag the cut edges past eachother until you had a tight conic fit to the rafters. Go inside and mark along the exposed cut edge, and add a couple inches of material for seam allowance.

To get the ring hole marked up I had the new conic cover in place o the yurt roof. I traced the inside ring diameter on the cover with sharpie, and added for seam allowance. Cut and sew. The whole cover was a perfect fit using easy mark in place technique.

I'd think the rafter liner could be fabricated using that technique. For a whole one piece liner, make the outside wall piece a few inches taller than the wall. Sew that to the roof liner at the wall line. I'd only go this route if the outside cover is one piece. If you want a two piece cover, as I did, just drape the roof liner down over the wall liner like the two piece outside covers. 8 meters is a huge yurt and a WHOPPING amount of one piece cover. Good luck.