We are sewing our roof seams with something called venture tape, a double sided tape that is sold by sailmakers. As recommended by a friend who does sew a lot of yurt canvases, this should help with the seam sealing. I have seen it in widths of 6mm-500mm. As it wouldn't add much thickness to the seam I guess a non-industrial sewing machine could handle it.
A product description says:
'Venture Tape is the premier double-sided tape for the sailmaking and cover making industries. polyester film is coated on both sides with an ultra high peel acrylic adhesive which is designed to adhere immediately to most types of sail cloth and canvas. It is virtually non yellowing and resists most strains of mildew.'
The glue melting plastic sounds pretty solid though! No holes...