Ti Goat Ptarmigan bivy users

I used a piece Gossamer Gear Polycryo cut to size….it's light weight and surpisingly durable.

Mine goes straight on the ground or on a 1/8" thinlight that supplements my torso pad.

+1 for the GG polycryo if a ground sheet is needed; They're SUL, cheap, and a little added protection/barrier for the bottom of the bivy.

No. I did the first time, then decided it was pointless. Careful site selection/clearing did the trick after that, if I had to set up on granite or something, I'd put it on my 1/8" thinlite, which I'd have along anyways.

The GG Polycro cloth is useful if not using the bivy, but it's so thin, I'm not sure what would rip that that then wouldn't also penetrate the bottom of the Tigoat.

If I was on a longer trip, I'd probably figure that a foot or so of patching tape would weigh the same as a ground cloth, and bring the tape.

I also use a GG PolyCro under my TiGoat Raven Bivy. The weight is negligible and it's more durable than I thought at first.
Is there any truth to the idea that your body weight, could "push" water through the silnylon bottom, say from camping on wet ground? I believe that I read this somewhere on a thread here.

nope, just throw mine right on the ground. Never had any issues doing it this way.