Flexible wall yurts use two basic tarpaulin skins: a canvas
treated skin or a poly vinyl weave tarpaulin.
Each has advantages and disadvantages.
Two basic weights are used in the poly tarpaulin: a 14 ounce
per yard (400 grams per meter) or 22 ounces per square yard (600 grams per
square meter). The cost of the 22 oz.
weight is approximately 40% more than the lighter weight, and generally lasts
about 40-50% longer. However, both are
prone to punctures from branches, squirrels and birds, so I recommend the
lighter weight, as the price per year will be slightly lower than the heavier weight.
Poly tarps tend to be
less pliable than canvas ones, and, in brisk winds, can fray if they are not
installed tightly to a frame. On the
other hand, canvas tarps are much heavier, and are prone to mould if snow is
allowed to accumulate on them, or if they are in high humidity/high rainfall
areas.
Canvas tarpaulins are easier to install, yet are a poor
choice if you are using an open rafter concept, as they may stretch over a period
of several years. However, the authentic
and aesthetically pleasing sound of rain or wind on a canvas is unequalled.
For solid or rigid-wall yurts, either canvas or poly
tarpaulin skins will suffice. If you are
insulating your yurt and the insulation is moisture-proof (rigid insulation or
Mylar-coated), condensation may build up between the tarpaulin roof and the
insulation. This problem is best addressed
by using poly tarps, and treating the skin with a mildew-resistant spray.
Each type should be treated with UV protectant annually, and
coated with flame retardant (at minimum, on the inside).
Overall, a poly tarpaulin is a better choice than a canvas
skin. Cost of canvas is two to three
times that of a medium weight poly, and lifespan (without treatment) is
comparable. While canvas is a more
environmentally friendly choice, the value of a poly tarp exceed that of a
canvas one.
