...Is my MYOG double ground cover. On the bottom is a garbage bag, on the top is space blanket, and held in place by duct tape.
Here is it in action: http://4.bp.blogspot.com/-7FNC8ef9Oho/T19L_rNEdQI/AAAAAAAAAbA/S-pFx1jcqRE/s1600/P1030114.JPG
Some may say it is "heavy" at 86g/3oz (includes weight of an elastic strap to hold it when it is rolled up). I defended the extra weight recently on my blog:
"It is perhaps a "heavy" ground cover from the perspective of SUL, but I feel it serves several important uses to make up for the small weight burden. For one the space blanket reflects back heat, giving a minor boost in warmth/insulation, but it is somewhat fragile--hence the garbage bag under it, which on the other hand is quite tough.
As I mentioned earlier, at times I use natural material to make a nest to sleep on, and this (especially pine boughs) can cause minor wear and tear on a ground cover and/or bivy. A double layer ground cover fixes this, and I also use this ground cover with my inflatable sleeping mat (Neoair Xlite) in the spring/fall to give added protection from the ground. I never use natural materials combined with my inflatable mats, as it is just not needed--my Xlite for example has an R value of 3.2, which is plenty of insulation and warmth for 3 season use.
The ground cover also is quite large, giving me a nice sized boarder around my sleeping space to put gear I might need (e.g. headlamp, cell phone, clothing, etc.) to keep it clean/dry. And finally, the ground cover also gives my bivy less wear and tear, so that I can continue to use it for awhile with less wear and tear. Bivies in general are not that cheap (nor are inflatable sleeping mats), so I feel it is best to take especially good care of certain pieces of gear."
For my tents I use just a garbage bag as a ground cover, and the weight varies from brand to brand of garbage bags. The one I use is only 42g/1.5oz and pretty tough, though not as tough as other thicker bags I used to use several years ago that are about 80g each.
I am surprised people don't use garbage bags more as ground covers.