Feedback on tent/bug shelter floor fabrics wanted

The 1.1 silnylon has a little more puncture resistance than the 1.1 silpoly, but the polyester won’t hold as much water. As I’m sure you’re aware, MTN 30D silnylon 6.6 is the best option in terms of durability and waterproofness. If price isn’t a worry and you don’t mind a tad more weight, that would be my choice.

I’d avoid the membrane silpoly, it’s just too weak and vulnerable to puncture, nor does it have enough HH. If low weight is very important the 7D .77 MTN silnylon from RSBTR is a good option, especially if you use a .7 mil polycro underneath all floors anyway. A bit expensive like the 30D MTN silnylon, however the quality sil coating on both sides and 6.6 weave makes the .77 silnylon punch above its weight. I made this 4.7 oz top zip bug bivy out of .77 floor and .50 noseeum. Performs well so far.

silpoly is good for a tent because it doesn’t stretch when wet like nylon does.  For a floor, this doesn’t matter, nylon better because it’s lighter for the same strength.

I use polycro ground cloth so my bivy floor doesn’t have to be waterproof, so I use 0.66 osy membrane, but the 0.77 osy silnylon wouldn’t weigh much more.

Also, my pad is 100% waterproof so the floor doesn’t really need to be.  Especially if the polycro will normally work and rarely get a hole.

I’ve sewn stuff with the 0.77 mtn silnylon and it was okay to sew.  Yeah, more difficult than heavier weight.  Sewing a long seam is always tricky – the top fabric slides relative to the bottom fabric.  They start out aligned, but by the time you sew to the end, one piece can be an inch long.

I use a few hand sewn stitches but most people use pins.  Do it at the beginning, end, and a couple places in between.  Hold the next pin/stitch between your fingers as the fabric gets pulled into the machine.  Practice with some long scrap pieces.