Groundsheet Space Blanket, Polycryo not tuff enuff

Tyvek is pretty tough stuff in resisting tears.
It's probably not perfectly waterproof for long term deluges, but it's not bad.

^ this :)

Subject pretty much sez it all.

Cruise new construction sites.

Tyvek is heavier than Cuben but Cuben is expensive. People have used polycro with success on thru hiked and such. The great benefit is that they are very light and very cheap.

You can buy small sections of tyvek pre-cut to a reasonable size on Ebay.
You can then cut it to the exact dimensions you want.
It comes in big rolls for houses, so some people on Ebay cut it into smaller pieces and sell it there at a small profit, to users who don't want to buy a whole roll.

And as mentioned, if you go past a construction site where they are wrapping a house, they will probably give you a remnant big enough for what you need.

I like 2-3 mil painters plastic from the hardware store. Completely waterproof, tough, cheap. Comes thicker if you want even more durability.

I did a google search and found a number of places. Prolite Gear for one. I'm going to ask my contractor friend. He probably tosses out pieces everyday that would work for me.

http://www.prolitegear.com/site/order.html?id=r6Pv8jiW:70.231.143.113

I just noted the weights there. Seems to be ~6g/sq-ft. Which works out to 5+ ounces for a piece the size of the nylon ground cloth I'm currently using (picked up cheap at REI garage sale). That weighs about the same.

Is that weight accurate? Is my math way off?

The first time I used polycryo I tore it up pretty fast–the sheet was ripped up by day three. Also I was frustrated with the wind blowing it all over. However, I just now threw away my second polycryo sheet after using it for two seasons! It was dirty and a bit ragged at one end and I have two fresh sheets waiting for use. Somehow I just learned how to treat this material and bam! this second sheet has been ridiculously indestructible. I found that the weight of my pad and sleeping bag kept the wind from blowing the sheet away. This sometimes means that in windy conditions I have to tuck the sheet in under my tent after it's set up. I love this stuff now. Which is all just to say, in my experience there is a definite learning curve to using polycryo as a ground sheet. But I totally understand your desire for something more durable. Just wanted to share my experience.

I've used all sorts of materials and then lightweight materials successfully. Ordinary polyethylene plastic tends to be too soft (it tears too easily). The heat shrink window film kits have plastic about like polycryo, and I find it works pretty good. It is just slightly slicker and tougher, and mine don't seem to tear. The big advantage is the size. It is so big that you can cut it to different sizes.

Once the stuff is on the ground, the breeze will blow it around, so I place rocks on the corners just until I get my ground padding on top, and then the sleeping bag on top. Soon the rocks get kicked away and the plastic does not tear.

–B.G.–

Either use more care in site selection , pre-cleaning of debris, caution in using the groundsheeet, or use much heavier material. Tyvek is the next step up, if that doesnt work for you cut a section from a blue poly tarp from walmart.

Polycryo generally works fine if enough care is taken. So does mylar, so does almost anything light. Care is the operative word.

I generall use mylar under a two person tent with me and my son. After quite a few nights on small pebbles twigs and pinestraw, its fine. We clean the site as well as possible first.

I am not sure if you guys there in the U.S. have this product but here in Australia we have a thermal paper that by law every house has to be wrapped in to meet energy ratings. What this is is a rip-stop type of material with a reflective (emergency blanket type of coating)on one side and what feels to me like an almost tyvek type of material on the other. Very light, durable and since I work on the building site….free. I used it for the first time a few weekends ago in roughly 4 degree celcius windy condition and the reflective side I put up so that it reflected my body heat that may have escaped through my airbed back up. It is also what I consider 'light', a roughly 2 meter square piece weighs less than 200grams ( I think 138grams comes to memory but don't hold me to that) and it doea 2 jobs well-thermal reflective and ground protection. Win win.

Maybe aluminized tyvek that used to be sold by Ron at SMD.

Antigravitygear sells it by the foot. So does Arrowhead Equipment. There are a multitude of others, including many sellers on the Bay of Evil.

Or, if there’s new construction near you, it might be worth bringing a six pack down to trade for some off of the end of the roll…

Joe @ Zpacks sells Tyvek by the foot.

I have used polycryo/window shrunk film quite a bit I have never been even a little careful with it. I have not had even little tears.

Bend, Oregon, was pretty much the epicenter, the poster child, for the 2008 real estate bust. Not a lot of new construction hereabouts.

Ben writes, "I have used polycryo/window shrunk film quite a bit I have never been even a little careful with it. I have not had even little tears."

Here, two corners torn (anchor rocks of sharp-edged granite).

The idea of my Exped air mattress and Nunatak quilt holding the groundsheet down by themselves is far-fetched. I had some stiff breezes up at 8,000 feet the past week.

M B chides, "Either use more care in site selection , pre-cleaning of debris,[…]" Trust me, these were the best of the available sites, I'm no beginner; and pre-cleaning of debris is rote for me. Polycryo is probably really good on soft ground, but out here in the west, where they call the wind "Mariah," in places where I hike, the ground ain't always so soft.

And in the sites where the ground was soft, it was very dusty, like talcum powder. The polycryo sheet is now nearly opaque brown.

Jack, your last explanation clears it up, I approached polycryo with extreme skepticism, not believing that it could work, but it does. However, you are doing the one thing it cannot do: putting sharp heavy edges on it, like rocks on rocks.

With some creativity, you could get around that, like, getting cuben type 2 sided tape, and tape on reinforced tieout points on the corners that you then put rocks on, or something like that.

Cuben would work well too on the corners, taped, then you could sew on 4 tieout loops, or something.

The wondrous polycryo, which is just insanely tough for its weight, really does work… unless you do exactly what you do, sharp rocks on rock, then it will of course tear, it's not magic. That's by the way why cuben exists, to take that toughness but make it not tear, by putting in a mesh of dyneema between the tough plastic sheeting.

The dirt issue is easily resolved, you can either wash the sheet out in a stream and let it dry during lunch, or hose it off on a clothes drying rack when you get home, that works great, I do it after each trip, dirty brown water then it's clean, no need to wash beyond that rinse.

But rocks on it, with sharp edges, no, that most certainly will not work, unless you do more to reinforce and create tieouts. Which is not by the way hard to do..

Tyvek at around 5 oz for the ground cover is the way to go, it's tougher, not water proof at all, but it does resist water a bit, when I first ordered that I had to scratch my head, it totally did not fit with UL ideas, but it is durable and tough, just don't think of it as anything better than water resistant, even new I think it has a hydrostatic head of somethign around 600 off the top of my head, and that's the thick stuff they use at construction sites, or that zpacks sells. The thinner stuff you can literally see light through the holes, it has no hydrastatic head at all, it's the softer variant, sometimes used for kites etc. I want to say it's 1433 or something, could be wrong. So get the stuff from the constuction guys or from zpacks, that's what you want.

You can also add tieouts to that by the way, some how to do that on bpl, a few folds of the corners and then some other tricks I can't remember, maybe grommets, and there you are.

Good luck. For all other circumstances I've found so far though, polycryo works, something that never ceases to amaze me.

I use sheet bend knots with my polycryo. Normally I stake it if I'm cowboy camping or until I have my shelter almost fully staked. You could use longer loops to put a stick through, and then pile rocks on that. I used to pile rocks and other things on my polycryo, but found that it was slick enough that a gust of wind would pull it out from under the rocks.

I think you'll find out that Tyvek picks up dirt, too. And it's heavier. Cascades volcanic ash (the major component of our mountain soil) sticks to everything!

Have you considered a piece of silnylon? More waterproof than Tyvek. I think those sharp rocks will put holes in almost anything, though.

Hey Miz Mary,

I have used silnylon in the past and it's certainly durable enough, but soil moisture which condenses on the underside causes dirt to stick, too, and I need to flip the sheet over to let it dry, which takes forever with silnylon for some reason.

Kind of like plastic food storage containers, such as Tupperware or Rubbermaid*, which always come out of the dishwasher with beads of water on them, while dishes and flatware come out completely dry.

So when I'm using silnylon I'm standing around, waiting for the mud to dry to dirt so I can brush it off, while the upper side, now on the bottom,** is starting to get moist.

Other than the slow drying time, silnylon works real good.

Yeah, our local volcanic ash is tenacious. And I just learned that the very very very fine dust that covers the trails and tent spots back in the Wallowas is even more so. It gets everywhere, creeps through even small openings, everything came back covered with dust and the stuff gets Jack sneezing a lot.

Harald Hope writes, "[polycryo] really does work… unless you do exactly what you do, sharp rocks on rock, then it will of course tear, it's not magic."

B-but I'm looking for backpacking magic here!

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* Rubbermaid: A word that causes both arousal and terror in me.

** Someone is bound to suggest that I hang the groundsheet over a branch or something to dry. Hereabouts, 99 and 44/100ths of the trees are conifers which are remarkably free of handy clothesline branches.

Okay, I took a little trip "outside the box" and did some web searching.

For the kind of attributes you want, it will require some added weight for the groundsheet. If you can accept about 4 ounces per yard for the material, this could be the ticket.

http://andrewroberts.com/fabrics/ptfeglassfabrictearresistant505.html

It's a sheet of .003" thin, flexible, tear-resistant fiberglass fabric which is teflon-coated for non-stick. It seems to be non-porous, because they have another special product of this type which is specified to be porous, and none of these others are specified porous. It comes in 38" widths, so you can cut it to size.
It's made to be used for ultra-thin conveyor-belts used in industrial machinery where heat and sticky-stuff might get on it.

I don't know the cost.

Tom, that Tear Resistant Teflon® Glass Fabric – 505 Series that you linked to looks pretty fancy. About twice the weight per unit area as Tyvek, but who knows about its tear resistance, its packability, how quickly it dries. Could be expense to find out. You go first.