Cuben as ground cloth

Wayne,

I think your 0.51 oz cuben groundsheet will be more prone to punctures than the polycryo groundsheet. The PET film on both sides of that cuben is 0.0008 inches in thickness, and readily develops tiny fissures from both abrasion and creasing. It has better tensile strength than the polycryo, but it is much more likely to get pinholes.

I agree with Colin. Many may disagree.

To me, using cuben as a ground cloth is kinda like a gold plated hammer. It won't work any better than polycryo.

For a ground cloth or floor of a tent, I'm a believer in the .18 mylar cubens, not the 0.08 ones. So a 1.26oz or 1.5oz cuben is what I would use. These are far more puncture and abrasion resistant than the .33, 0.51 and 0.74oz cuben varieties. My HMG Echo I has a 1.5oz cuben floor and I've been very happy with that. I have stuff sacks made from all of the lighter variants and they do develop tiny pinholes over time, so I wouldn't want to spend this kind of money on a ground sheet that wouldn't last very long.

…but will it work at all? Obviously, buying one this thin will require care; I knew that when I bought it. I certainly appreciate that it is way too expensive, but I have already purchased it. I am wary, however, about whether or not it would keep me dry if it were to start dumping rain and my site were to turn into a bog.

1) If I haven't developed any punctures, will it hold out the water beneath me?

2) If I do develop punctures, I can obviously tape over them. Are you suggesting that the punctures would be so small that I wouldn't notice them? IF so, am I likely to get wet from these?

Sorry to ask such newbie ground cloth questions. I've never really given much thought to them. I've certainly never had one fail. It does seem like it could ruin and otherwise well planned shelter system.

Thanks-
Wayne

1) If I haven't developed any punctures, will it hold out the water beneath me?

Yes, Mylar is waterproof. It's just not all that strong by itself, hence the Dyneema threads to reinforce it.

2) If I do develop punctures, I can obviously tape over them. Are you suggesting that the punctures would be so small that I wouldn't notice them? IF so, am I likely to get wet from these?

You'd probably notice the spots where water is entering through the holes. If you're careful, they'll probably be pinholes, so in most cases you probably won't notice, I would think.

The heavy-duty 1.5 oz Cuben fabric on my Echo insert seems pretty intense. That would be my choice for a ground sheet, if I were getting a standalone groundsheet.

Hi Wayne,

I think many have the policy that you should not rely on your ground cloth to be fully waterproof. It can be very difficult to keep small holes from developing in even the most heavy duty durable material.

I do believe cuben is durable enough, especially the heavier versions, but will eventually develop holes just like anything else.

As long as you pitch your shelter on high ground, minor leaks are not an issue.
I don't know how many times I've had friends pitch in a depression, only to find their heavy duty waterproof polyester bathtub floors full of water after a rain.

I had a piece of the .51 that joe uses. I personally saw how frail from an abuse standpoint that material is. In my opinion it will in now way handle any sort of puncture or abrasion. the first time you put your weight over any pointy rock or stick, it will come through.

Not that plycro is really any different, except to replace the polycro it wont cost you 75.00

There is a reason that material is not used in any tent floors or backpacks.

With my cuben stuff sacks using 0.08 mylar, I had no idea they weren't fully waterproof anymore until I filled one up with water as a test. The water immediately started dripping through the pinholes. There were lots of pinholes and pretty much all of them were really too small to see. So I suspect you could try taping/patching the pinholes for a bit, but eventually you'll just wind up with a ground cloth totally covered in tape. This stuff sack I mentioned is my miscellaneous stuff sack that gets tossed around, slid around on rocks etc. Your ground sheet would have an easier life than this with good care, but I still wouldn't trust it in the long term.

Since you own it, I would use it and just monitor how it's holding up. It's not going to all of a sudden leak like a sieve. It'll be waterproof, then a few trips later it might have a couple pin holes and then after a large number of nights it'll be un-useable. You can test it at home to see how well it's holding up. I would happily use a new one for a bit, I would test it to see how it's holding up after 5 nights or so though.