View Full Version : Question about Tyvek and polycro ground sheets.
So, I am trying to decide if I should carry a Tyvek or Polycro ground sheet on the colder portion of my thru hike. I am planning a mid February start at Springer and was wondering about the durability of the polycro window insulation you can buy at the hardware store vrs Tyvek.
I have hear peole say the polycro is semi fragile and subject to having things poke thru it when using under a tent, definately more so than tyvek..but I have people say they just clear their tentsite as normal and they have had no real issues.
The interesting thing for me with tyvek is the insualtion quality. I understand it has an R value of ~1.8 and this is interesting in that if it is truly cold and I need extra warmth (especially in a shelter) I can use it as an addition vapor barrier, insulation with my sleeping bag. I was wondering if because of the R value, is there any insulating qualities when using it as a ground cloth on cold frozen ground when tenting or tarping.
Thanks
NCmedic.
I wrote this article about ground cloths...maybe it will help?
http://www.pmags.com/ground-cloths-a-quick-overview
Many people use polycro sheets for the length of their thru-hikes. All depends on how hard you beat on gear. Keep an extra in a bounce box?
jakedatc
10-25-2012, 10:26
Where did you see Tyvek is R1.8? i saw one site say .06 Dupont says Thermowrap creates R2 when used with a 3/4" air space. which would be interesting to put over an airpad
thermowrap is metalized and is 2.6oz/yd so it's pretty heavy. but to put a pad sized piece between your pad and sleeping bag maybe worth it.
normal housewrap is 1.8oz/yd so it is still heavier than polycro by quite a lot.
http://www2.dupont.com/Tyvek_Weatherization/en_US/tech_info/guide_specs.html
Window film is surprisingly durable.
There's no way tyvek is R1.8.
My main draw for tyvek is that it can quickly be laid out, where window film is blown around by the slightest wind and takes a few rocks and use of trekking poles to hold it down while putting a shelter over it. The main draw to window film, aside from weight, is that it compresses to the size of a deck of cards that is easily packed in an used crook or cranny where tyvek has to be rolled and folded and takes up real space.
Yeah, I thought I read that Tyvek has a negligible R-value. I'd love to hear if that's incorrect. It would change my planning quite a bit.
Zippy Morocco
10-25-2012, 10:52
I just started using polycro and like it. The stuff Gossamer Gear sales is stringer than the stuff you get at Ace. I was surprised by its durability.
bubonicplay
10-25-2012, 10:56
I don't even believe tubeless has an r value of .6. Doesn't seem like it because a 1/8th foam has .7.
I could believe R0.06 because if you stack 50 of them to get the insulation of a blue foam pad, you'd have a fairly thick surface, and surely it'd provide some level of insulation.
The R1.8 might be possible if it were draped below a hammock, but that relies on air space and could be done with any number of fabrics.
I found that tyvek is far more versatile for me. I keep my tyvek footprint at the top of my pack so that i can pull it out and sit on it when i break regardless of where i am and it is always the first thing i pull out to layout my gear when i reach a shelter. i tried using polycro the same way but it just shredded after a few uses over rocks, sticks and the splinters found in shelters. my tyvek has been through countless washes and is just getting lighter and softer each time. when i am hiking i dont want to have to worry about how carefully i have to handle my gear. everything i carry gets used and gets used hard. none of that ultralightweight fragile be careful how i pack it because it cant be replaced because i spent all my money on it gear.
rusty bumper
10-25-2012, 11:55
I use a sheet the Gossamer Gear polycryo sheet cut down to 40"x60". I spread it out alongside my tent to sit on while reading or eating dinner. When I turn in for the night, I fold it down to a size that fits in the "vestibule" of my Tarptent Moment. It serves as a ground cloth for those things that stay outside at night. The stuff is really light and so it can a bit difficult to get it dried out in the wind...it really wants to takeoff. In over 2000 hiking miles, I managed to get one small tear but it never grew to a larger size. I don't use a footprint for my tent so I'm not sure how durable it would be in that case.
Slo-go'en
10-25-2012, 12:04
The main purpose of a ground cloth is to protect the bottom of your (expensive) tent. For that I'll stick to Tyvek. And as snifur pointed out, it can have multiple uses. Sitting pad or tarp or even made into a poncho. There is a version of Tyvek often used to make kites which is much lighter than the house wrap stuff, I need to get some. The piece I've been using for the last 5 years is starting to show some wear.
As for Tyvek's insulating properties, that would be negligitable. The matterial doesn't conduct heat very well, but is too thin to have much effect.
mainebob
10-25-2012, 12:21
i had switched from tyvek to window film a last year. i am going back to tyek this year. the plastic was harder to put down and i used the tyvek for a ground cloth for the tent, used it to take a break and not get wet or dirty, and also use it in the shelter under my neoair for a little more protection. i think it is worth the 2 or 3 oz difference in weight for the increase uses.
Where did you see Tyvek is R1.8? i saw one site say .06 Dupont says Thermowrap creates R2 when used with a 3/4" air space. which would be interesting to put over an airpad
thermowrap is metalized and is 2.6oz/yd so it's pretty heavy. but to put a pad sized piece between your pad and sleeping bag maybe worth it.
normal housewrap is 1.8oz/yd so it is still heavier than polycro by quite a lot.
http://www2.dupont.com/Tyvek_Weatherization/en_US/tech_info/guide_specs.html
Hmmm....maybe my friend is thinking of Tyvek with a dead air space...I will aske him next time I talk to him.
jakedatc
10-25-2012, 18:38
Or he looked at the weight 1.8oz per sq yard and mistook it for the R value? Thermowrap is not very common for hiking .. most people use housewrap.
right now i use 3mm painting drop cloth.. i need a 10' x 4' diamond for my Lightheart Solo so finding the wider width stuff is harder without buying a whole roll.
Your tent or sleeping bag won't slide on Tyvek as much as it will on the Poly window film, and you can wash Tyvek, but Tyvek tends to hold onto little bits of leaf litter, pine needles, etc. once it gets older and fuzzes up on the surface a bit. Also, Tyvek is not 100% waterproof when brand new, and loses its water repellancy gradually as it wears. Anything durable and truly waterproof won't be very light. I started out with a 1.9 oz./square yard (before coating, I believe) tarp back in the 1970s, and it did well for a few years before the polyurethane coating flaked off. I don't sleep on the ground regularly anymore, but occasionally (during the winter when I might use a shelter with friends) I will bring a heavy duty Space Blanket, which is wonderfully waterproof, relatively nonslip, but definitely not light, never mind ultralight.
Violent Green
10-25-2012, 19:22
Tyvek 1025D may tighten the gap between polycro and old school House Wrap. 1025D is the lightest hard-structure Tyvek made and is 1.25oz/yd where as typical Tyvek is 1.85oz/yd. Lawson is going to offer some soon so we'll see how it works in the field.
http://www.materialconcepts.com/store/products/36-x-10-yard-tyvek-1025d
Ryan
Wise Old Owl
10-25-2012, 19:46
The main purpose of a ground cloth is to protect the bottom of your (expensive) tent. For that I'll stick to Tyvek. And as snifur pointed out, it can have multiple uses. Sitting pad or tarp or even made into a poncho. There is a version of Tyvek often used to make kites which is much lighter than the house wrap stuff, I need to get some. The piece I've been using for the last 5 years is starting to show some wear.
As for Tyvek's insulating properties, that would be negligitable. The matterial doesn't conduct heat very well, but is too thin to have much effect.
Totally agree,.. closed cell foam (Old School) addressed this... Today these thin materials are disappointing. I appreciate the merit of the post.
Your tent or sleeping bag won't slide on Tyvek as much as it will on the Poly window film, and you can wash Tyvek, but Tyvek tends to hold onto little bits of leaf litter, pine needles, etc. once it gets older and fuzzes up on the surface a bit. Also, Tyvek is not 100% waterproof when brand new, and loses its water repellancy gradually as it wears. Anything durable and truly waterproof won't be very light. I started out with a 1.9 oz./square yard (before coating, I believe) tarp back in the 1970s, and it did well for a few years before the polyurethane coating flaked off. I don't sleep on the ground regularly anymore, but occasionally (during the winter when I might use a shelter with friends) I will bring a heavy duty Space Blanket, which is wonderfully waterproof, relatively nonslip, but definitely not light, never mind ultralight.
Interesting take Polycro is best suited as the tarp not the bottom... not sure how this got started Lets stick to a space B or better! (the issue is pin holes or more)
I used to also mistakenly believe Tyvek had a greater R Value than it really has but since I checked out the Tyvek website I found I was wrong too. Even though Tyvek comes in various grades some being slightely heavier and more durable Tyvek doesn't come anywhere near the OP's stated Tyvek R Value. Per Mags groundsheet blog, not only can Polycro shrink in hot weather, never mind about being placed in the dryer, Tyvek can also shrink drastically if placed in a dryer for too long on a higher setting or if a corner of it gets too close to a campfire, let's say. I discovered this when my rectangular(24" x 84") Tyvek groundcloth was becoming parrellogram shaped! When heated too much Tyvek can become a hard brittle wad of white Saran Wrap. However, a washing when it's new and then letting it air dry or drying on a lower dryer setting will make it soft, quiet, and easier to stuff into a pack. And, with repeated use(washings) Tyvek does eventually lose some of it's water resistance.
Tyvek 1025D may tighten the gap between polycro and old school House Wrap. 1025D is the lightest hard-structure Tyvek made and is 1.25oz/yd where as typical Tyvek is 1.85oz/yd. Lawson is going to offer some soon so we'll see how it works in the field.
http://www.materialconcepts.com/store/products/36-x-10-yard-tyvek-1025d
Ryan
I remember he mentioned it, but I hadn't paid enough attention to realize it's much lighter than regular tyvek. I hope Lawson starts posting here, especially considering what's happening on that other forum.
Violent Green
10-25-2012, 23:12
Here were the sizes and weights he was going to offer. Roughly an ounce less on the 30"x84" compared to regular Tyvek.
30" x 84" (2.43oz)
60" x 96" (5.55oz)
60" x 120" (6.94oz)
60" x 160" (9.25oz)
Ryan
I'm hoping it's still stiff. I'd like to use it as a warmer weather unpadded sit pad. In cooler weather I use a small piece of foam, but that's over kill for the rest of the year.
garlic08
10-26-2012, 09:09
I had a winter experience with Tyvek once where my body heat froze the Tyvek to some packed snow, and I left a trace--pretty much ruined the Tyvek too. I stopped using Tyvek and I have never had that issue with my silnylon. I don't winter camp that much, and it may have been a freak occurrence.
I completely agree that there is essentially zero insulation value to Tyvek, no more than a single sheet of paper.
Henry Shires says on his website that he virtually never gets tents back for floor repair, so he does not recommend carrying a groundcloth.
My conclusion from the above points was to stop carrying a ground cloth, even (or especially) in winter.
pyroman53
10-26-2012, 11:59
here's a cut & paste from my journal from a night a few years ago...I appologise for the wordiness but it was easy to just cut & Paste...
At about midnight I awoke to Andy searching for a flashlight, claiming he was being bothered by ants. Well, "Big deal," I thought. Heck, I had squashed a few ants, flicked a few others, and otherwise just ignored a few others. It is standard practice when you tarp. A few creepy crawlers are no big deal. So I mumbled something and went back to sleep. Andy kept at it and eventually asked for my headlamp. I asked him how many ants are a "bunch" of ants. "Oh, probably 40 or 50," he said. "Whoa! That sounds like something worth putting on my glasses!" And so I did.
Yep, 40 or 50 carpenter ants, crawling over, around, and under his new Tyvek ground cloth. Were we going to have to move the tarp in the rain? Crap! It’s raining! It’s dark! Crap!
But, then we noticed the ants were only on the Tyvek – not on my silnylon ground cloth. Apparently they saw "Tyvek" and thought "food". Tyvek is a fairly waterproof paper-like material that is used to wrap the walls of new houses to provide a vapor barrier. Hikers use it because of its light weight. I later learned that carpenter ants are nocturnal feeders that search out rotten and decayed wood and other cellulous (can you say Tyvek?).
Once we stowed his ground cloth, and spread out my poncho for both of us to use, the ants disappeared and we went back to sleep, having shared another magic moment with the natural world. Later, as we discussed this incident, Andy remembered that during his prep hike in Pennsylvania, there were a lot of carpenter ants that night as well, but he was safe and secure in his bug tent so he didn’t pay them much attention. We both agreed that Andy would wash the Tyvek when he got home in the hopes that the washing would eliminate whatever had attracted the ants. We shall see.
jakedatc
10-26-2012, 12:09
"other cellulous (can you say Tyvek?). "
Tyvek isn't cellulose or any other natural product. it is plastic
"TyvekŪ is formed by a fully integrated process using continuous and very fine fibers of 100 percent high-density polyethylene" - DuPont
pyroman53
10-26-2012, 12:14
So I see...I stand corrected. Don't know where I got that idea. However...it was one heckova rodeo for some reason. Maybe it was a coating or something. The printing probably isn't polyethylene.
jakedatc
10-26-2012, 12:23
Could have spilled something on it.. even if they wiped it up, a bit of residue could attract them
bamboo bob
10-26-2012, 12:33
I have used the same piece of tyvek for many years. I never thought about r value only as protection for the tent bottom. The "light" tent materials are just not very durable so tyvek is worth the weight. Also you don't need a true footprint for your tent, just the a rectangle to cover the part you lie on.
Cookerhiker
10-26-2012, 16:35
A few months ago, I went to JoAnn's fabrics and bought a length of nylon, cut to the length of my tent. The width is just about double my tent's width (Mountain Hardwear Sprite 1) so I double it up. So far, it's worked nicely on 100 miles of hiking in the Sierra, the 82 miles I just finished on the Allegheny Trail, and shorter hikes. It's easily washable after each trip. I was even able to match my tent color.
http://www.joann.com/sport-nylon-many-colors/prd13084/
I'm interested Garlic. So, you sleep in a tent, under a tarp, cowboy without a groundcloth never even in the winter? Do you mostly sleep in a tent or hammock? I can see not having a ground cloth under your tent but do you just lay on the ground in your sleeping bag or atop your sleep pad while cowboying, even in the snow? What kind of sleep pad do you typically use, if any?
Nylon, huh? Size and wt Cooker Hiker?
garlic08
10-27-2012, 08:50
I'm interested Garlic. So, you sleep in a tent, under a tarp, cowboy without a groundcloth never even in the winter? Do you mostly sleep in a tent or hammock? I can see not having a ground cloth under your tent but do you just lay on the ground in your sleeping bag or atop your sleep pad while cowboying, even in the snow? What kind of sleep pad do you typically use, if any?
I use my Contrail year 'round now. The silnylon floor has turned out to be incredibly rugged. I use a Z-rest pad and in snow (infrequent) I add a piece of Reflectix duct insulation--great stuff for the weight and cost.
I'm just about to retire the Contrail after over 6000 trail miles (including thousands of desert miles), and one recent 4500 mile bicycle tour, over six years. The failure points are the zipper and a couple of spots where guy lines attach to the canopy. The floor is good as new (well, almost--no holes or tears or visible wear) despite never once using a ground cloth.
Cookerhiker
10-27-2012, 15:17
Nylon, huh? Size and wt Cooker Hiker?
Don't know the weight - seems pretty light to me but I have no scale. I had the length cut to about 84 inches (I'm 5'11"). The fabric width is 58" so I double it up which means the vestible isn't covered but all other parts of the ground are.
It easily rolls or fold up to a size where I store it in a newspaper sleeve-type plastic bag and place it in my tent bag next to the poles before stuffing the tent & fly.
johnnybgood
10-27-2012, 15:50
Having access to a product used in the medical setting for bedsores, MedLines absorbsant barrier works well as a ground sheet.
Although it has no R insulation value it protects the tent floor against wear &tear while acting as a vapor barrier. Not sure what the weight is but it can fit in small stuff sack.
Yeah, kinda figured you were doing something like that Garlic with a closed cell foam pad. I wouldn't want to put one of my Neo Airs directly on the ground though. I'll use the polycro or window kit wrap in the desert on sand, although it does tend to blow around, even more so than Tyvek, or a 24" x 84" 1.25 wt piece of Tyvek, or a 1/4 closed cell foam pad from MLD or ProLite under one of my Neo Airs. I mostly cowboy but also tarp during all four seasons while hiking. I use the shortie 20" x 47"(the latest 2012 version) for 3 season thru-hiking with my empty pack under my lower half and a women's 20" x 66"(the latest 2012 version, longer which if I curl up I can fit my entire body on the pad, it also has a 3.9 R-value which affords additional insulation) for winter or COLD weather hiking. If I'm in a shelter such as my Gossamer Gear's "The One" I use no ground cloth per say. The shelter's floor becomes my ground cloth.
Furlough
10-27-2012, 16:08
I have used the same piece of tyvek for many years. I never thought about r value only as protection for the tent bottom. The "light" tent materials are just not very durable so tyvek is worth the weight. Also you don't need a true footprint for your tent, just the a rectangle to cover the part you lie on.
I concur with Bamoo Bob. I have a piece of Tyvek that came from a house construction site. It was the cut out from the windows, and the workers had thrown it and several other trimmed pieces away. I asked for this one and was given it. So....free, relatively light weight, used more to protect the bottom of the various tents I have used it with and to protect my sleeping pad/bag when in a shelter or under the stars. Never even considered it as insulation. Also after 5 plus years no issues with leakage through it.
staehpj1
10-27-2012, 16:19
If using a tent or bivy I do not use a ground sheet of any sort. For cowboy camping I might use one, but have thus far carried a bivy when cowboy camping often sleeping on top of it.
I have not found that I am all that hard on tent floors.
jakedatc
10-27-2012, 17:26
Don't know the weight - seems pretty light to me but I have no scale. I had the length cut to about 84 inches (I'm 5'11"). The fabric width is 58" so I double it up which means the vestible isn't covered but all other parts of the ground are.
It easily rolls or fold up to a size where I store it in a newspaper sleeve-type plastic bag and place it in my tent bag next to the poles before stuffing the tent & fly.
It says 93g/m which is like 3oz/ yard twice as heavy as Tyvek and you double it up so 4x tyvek.
Wise Old Owl
10-27-2012, 20:12
A few months ago, I went to JoAnn's fabrics and bought a length of nylon, cut to the length of my tent. The width is just about double my tent's width (Mountain Hardwear Sprite 1) so I double it up. So far, it's worked nicely on 100 miles of hiking in the Sierra, the 82 miles I just finished on the Allegheny Trail, and shorter hikes. It's easily washable after each trip. I was even able to match my tent color.
They also sell some ripstop..
http://www.joann.com/rip-stop-nylon-many-colors/xprd560961/
I carry a piece of Tyvek with me. Most of the time, I am a hammock hanger. However, I sometimes find myself pitching my Hennessy Hammock on the ground like a tent or bivy--if appropriate trees are not present (or if rules prohibit hammock use). The Tyvek prevents the hammock from rubbing on the ground and dirt--(which could--over time--weaken the very cloth that has to hold my weight when I use the hammock in the conventional way). I sometimes lay out the Tyvek on the wet ground if I want to sort through my gear. I keep the Tyvek near the top of my pack--and in certain conditions I will get the Tyvek out of the pack and sit on it for breaks or lunch. If I sleep in a shelter, I put the Tyvek under my NeoAir pad to protect it from whatever is on the shelter floor (tracked in dirt and rocks, slivers, nail heads etc). Tyvek is a versatile piece of gear for me.
BigGulps?SeeYaLater!
09-02-2014, 09:31
Hey thanks for the great idea on multi-use of a tyvek groundsheet. I'm a china-shop-bull with gear. "ultralightweight fragile be careful how i pack it because it cant be replaced because i spent all my money on it gear..."
Um yeah that's def not me either.
My buddy uses his Exped Multimat the same way you use your groundsheet...I never bought one because that damn thing's 11 ounces. Eff that. But duh...just use the tyvek...good idea, thanks!
Not sure if this is true or not but I have heard from more than one source that if you use Tyvek be sure to put the printed side on the ground for maximum waterproofness....
I can't imagine not putting the printed side to the ground with all white facing up but you never know... :)
Twogears
09-02-2014, 13:22
I have experimented this summer with not using a ground cloth. 450 PCT miles, 250 CT miles, 250 misc trips (so about 2 months worth of nights) and honestly can't see myself using one again. I currently use a Big Agnes tent and its floor keeps moisture out. This spring will be switching to an MSR Fly Lite (saw a beta version of this tent in Durango).
I used a pieces of tyvek for years. By the way, tyvek does eventually lose its water resistance.