First of all, let me state that I normally backpack in the national parks of California in the summer, so it tends to be cool and dry, except when it gets cold and rainy. I use a solo cuben fiber tarp pitched no closer than five inches from the ground.
For years, I have used simple ground sheets to keep the soil moisture from getting into my sleeping gear. So, I used mylar space blankets and then simple plastic sheets (window treatment plastic). Neither of these seem very durable. The mylar is brittle and rips up. The plastic tends to get a hole about the size of my boot heel. Currently my plastic sheet goes about 1.3 ounces.
So, what is the state of the art for UL ground sheets?
I notice that cuben fiber ground sheets are sold, and these tend to have bathtub sides maybe 3-5 inches tall, but they weigh three or more ounces. That has the effect of helping keep off rain spray, I guess. Maybe a flat one would be ineffective, even if lighter. We could extend this thinking and do the sides taller, and then the whole thing starts to be a bivy sack, but it gets heavier. I don't need extra warmth for the sleeping bag, so I am inclined to keep it ventilated.
For those of you who use cuben fiber this way, what is the weight of the fabric? Apparently most of the commercial products are about 1.0 ounce CF material. Did anybody try something thinner? How did that work? I know. Cuben fiber is pretty pricey, so you would want it thick enough to last a while.
I was thinking of crafting up one, and I figure that it would require at least two linear yards of material. Also, I am trying to decide whether to hem it by sewing, or hem it by folding the edge and taping, or both. I don't want to end up with an expensive mess that weighs more than my current plastic sheet.
Has anybody been down this road before?