Tyvek "Home Wrap" is an ideal material for ground sheets. It is waterproof, and very abrasion and puncture resistant. Tyvek is stiff, and foldable like thick paper. It will not bunch up or slide around under you like other fabrics.
Fold up the edges and tape the corners to make yourself a bathtub floor for your tarp. Cut it to size using regular scissors to make a tent footprint. It does not fray and you do not need to hem or tape the edges.
This material is white on one side, with a blue and red Tyvek logo printed on the other side.
Size: 5 feet by 9 feet (1.52 x 2.74 meters)
Groundsheet weight: 9.2 ounces (262 grams)
Material Weight: 1.85 oz. per square yard (62.7 grams per square meter)
Groundsheet needs to be broken in, so haven't used it. My first experience with this product. My suggestion is for zpack to provide instructions to break in product when shipped before using.