MYOG: tyvek ground cover / bivy combo

[t.darrah]

JJ,
I have had this project on the back burner while I worked on my MYOG AlpineMid (see recent post). I will continue to work on this project and I'm presently searching for a good source of 1443 tyvek to use. Please send me a PM regarding your interest.

[Greg Mihalik]

JJ,
Click on Thom's name, to the left of the post.
Look below the avatar for "Email This User".

[Nate Meinzer]

Have the BPL testers weighed in on this project yet?

[t.darrah]

Nathan,
PM sent.

[Nate Meinzer]

Thom mailed me an early prototype to get some feedback on its performance. I've only spent one night in it, but wanted to post some initial impressions and pictures:

The bivy is made from homewrap insulation grade Tyvek and weighs about 8 oz. The seams are bonded, not sewn, and the cut tapers toward the foot. There entrance is a simple opening in the head of the bivy with no zippers or velcro. It is 76" long and has a maximum girth at the opening of 30". There is plenty of room for a full-sized sleeping bag and mattress (I used a Big Agnes Regular (72") AirCore) inside the bivy.

Pro's:

Stiffness: I really like the material. While it is certainly stiff (and I did nothing to soften it), to me, this was desirable as I get very irritated with nylon-top bivies that blow into your face while you sleep or start to sag on you overnight. This bivy stayed in the position I placed it in all night long. I did add a guy-line to hold the hood up, but the stiffness of the material allowed the one-inch bond above the head-area to act like a bivy loop and kept it up, out of my face, despite moderate wind. (No more than 10mph.)

Warmth: Wow. This material is WARM. In the middle of night, I was a bit overheated in my 35F bag and ended up unzipping it and draping it over myself like a quilt. Very impressed with this aspect of the material.

Windproofness: Again, very amazing. This material is much more windproof than lightweight nylon and doesn't flap in the wind and smack you in the face . The bivy has a wide enough circumference so that even with my 2.5" thick air mattress, I was completely below the opening, completely surrounded by the bivy, and the wind passed over me.

Condensation: I experienced no condensation or dampness, although I was on a ridge-top not near water and there was no dew in the morning, so this requires further testing. I'd be surprised if a bivy this warm wouldn't produce some condensation, so I'll put it to the test next weekend.

Waterproofness: Hard to say as there was no rain or puddles on the ground. I've had dew soak through a DWR nylon/silnylon bivy (that cost a pretty penny compared to this one), so if the Tyvek resists dew and water well without suffering from heavy condensation issues, I will be a true convert.

Cost: Clearly, one of the best things about the bivy is how cheaply it can be made.

Cons:

Noise: Yes, it's crinkly and loud. Noise of materials seems to bother some around here, but I don't really care. When the wind would hit the guyed out head-area, it would hum a bit, much like a tarp might in strong winds. I imagine the Tyvek hums louder and at lower wind strength than other materials. One could soften the tyvek and reduce the noise, but I prefer the stiffness of the material so I'd rather deal wtih it.

Entrance: This is just an early prototype, and Thom has been working on other openings, but I would prefer a side zip or velcro opening. I really liked how the bivy completely surrounded me and wouldn't want to sacrficie that for the ease of sliding in from the side.

Roominess: If you placed the bivy on top of your mattress or use a smaller mattress, the bivy would be incredibly roomy as it is. With my 2.5" air mattress I would have liked just a few more inches of wiggle room to turn over in my sleep more easily, but it was a really good fit. I'm 5'8", 155. Taller/bigger people probably wouldn't be able to get away with the big air mattress inside the bivy as I did.

Aesthetic: I wish I were one of those people who did not care about the, uh, "ghetto" aspect of using a Bivy with DUPONT, TYVEK, and worst of all, NASCAR printed all over it. Alas, I am not. It's not a huge deal, but the bivy would be a lot more marketable if it were made in plain white or even dyed green. That's probably low on the list of modifications, as this is just a first try, but it would be nice.

Compressibility: It could be more compressible, though this isn't a big concern for me. I believe it will become more compressible with usage.

Weight: Would it weigh less if it used a lighter type of Tyvek? But how would performance suffer? I don't know enough about the material to say, but I think Henry Shires' "SubLite" is made from a lighter Tyvek than this and performs decently, or so they say.

All in all, I was very impressed with the bivy and will continue testing and giving feedback.

[todd]

Nathan,

Nice review. It looks like a quality, simple piece of gear and I like it. I, too, would like a half side zip.

I'm anxious to follow this….

Todd

[Nate Meinzer]

I forgot to mention that the bivy is tough. I sat up in it several times stretching the area where the seams meet the opening and they didn't pop off or even threaten too. The bonding technique works well (possibly better than sewing Tyvek?) and produces a tough seam.

[t.darrah]

Nathan,
Thanks for taking the time and effort to write and post your test report. I look forward to hearing additional comments as you use the bivy on upcoming trips. In my own testing I also have found the tyvek bivy to be very warm adding at least 5* additional warmth to a given sleep system.

The tyvek is very weather resistant and I think you will be pleased with its performance when used in combination with a tarp.

The seams used in this early version are a 2" overlap and bonded, not sewn. The 2" seam is very strong but heavy. On the next version I will provide to you the seams will be a bonded 1" overlap.

Thanks again for posting your report and pictures.

* Early versions I kept the TYVEK logo out so readers could see i was using house wrap grade tvvek. More recent versions, and nathans replacement, will be either all white or dyed (if dying works well). Bonding is via a spray adhesive that has worked very well to date.

Thom

[Joe Clement]

What are the seams bonded with? And couldn't you turn it inside out to get rid of the logo?

[Nate Meinzer]

The seams are heat-bonded, I think. There may be some tape involved? I couldn't quite tell. The printing is bright enough that it would be visible even if turned inside out.

[t.darrah]

The seams are not heat bonded, the seams are bonded using a spray adhesive. The seams are water tight and require no seam sealing, in demolition testing the bonded seam is stronger then the material.

[Simon Weiss]

UltraLight Newbie here…

This is a great project. At the very least, a good way to get a decent bivy, and prototype in a cheap, easy to manipulate material. Thanks for sharing all your work.

From some cursory research I see the "paper" and "fabric" style Tyvek.
The "fabric" style tyvek is what's used in lab coats/coveralls.
The "paper" style is used in envelopes and home wraps.

It looks like these pictures are showing the "paper" style. Anyone tried to use a combination of paper tyvek on the bottom and fabric tyvek on top to reduce weight or increase breathability?

-simon

Is it hard to join/sew/glue fabric to paper tyvek?

Has anyone found areal densities (weight/yd) for the different kinds of tyvek?

[Nate Meinzer]

Someone in this forum made a fabric Tyvek Bivy a while back. Search for tyvek in the MYOG forum and you should run across it.

This bivy was made with the homewrap variety, which I believe is 1.85oz/sqyd.

Questoutfitters sells tyvek.

[Erik Graf]

Been following this post for a while.

I've used a Tyvek ground cloth for a long while – prior to my first use I washed it and it's much softer and far more quiet.

Thom – or whomever wishes to answer – the photos in this thread appear to have "unwashed" Tyvek – have you tried to wash your Tyvek bivy project afterwards and if so, how did the spray adhesive hold up?

Thanks

[t.darrah]

Erik G,
Washing has no effect on the adhesive used. The bonded seam is water tight and very strong, the unseamed material/fabric will fail under stress before the seam. This is true with the original 2" bonded overlap seam and the more recent 1" bonded seam used on this project. I hope this helps.

[Nate Meinzer]

Thom is correct.

I washed and dried the bivy to "soften" it and see how the performance and construction would be affected. The only part of the bivy which retained its original texture was the bonded seams, and they were not damaged at all.

That said, after having tested the softened version, I believe I prefer the original, unsoftened tyvek. I believe, but am not sure, that it is warmer, and also, it holds its shape so as to not blow in your face or collapse while you sleep–a big plus for me.

I did use the bivy in a heavy dew and condensation-prone area with no condensation on the inside of the bivy. It was very slightly damp in the morning, on the inside, but considering the tarp I was under was soaked with condensation, I was surprised that my bag was completely dry.

[t.darrah]

Nathan,
I have had similar results in personal testing, the inside of the bivy will have a damp feel but have no visible moisture. I also prefer the stiffer unwashed material after having used both. The tyvek will soften with use over time but not to the level of prewashing.

The tyvek bivy is very warm adding at least 5*, if not more, to a given sleep system.

[Joe Clement]

You can take about 15 minutes and work the house-type tyvek in your hands, ribbing it against itself, and soften/quieten it substantially. That would allow you to selectively soften certain spots on the bivy.

[Erik Graf]

Appreciate the comments vis-a-vis washing this constructed bivy.

Thom: can you advise what sort of spray adhesive you are using? (ie. brand name)? Or is that a "trade secret".

:-D

[Bryant Burton]

Hello all –

I was looking the posts here and recalled a guy that made tyvek ponchos in different colors. I found his site and he also sells Type 1016 Tyvek with no logos by the foot (10ft widths). Its pricier than e-bay but only by a few cents per foot. Here is a link if your interested.

http://goodling_outdoor.tripod.com/1016.html

– Bryant

[Nate Meinzer]

Does anyone have any experience with 1016 Tyvek performance versus housewrap Tyvek performance?

[t.darrah]

I've limited my projects to construction grade tyvek. It is reasonably light, very tough and the performance has proven good both in weather protection and breath-ability with my personal limited testing. I've been using a 3M spray adhesive that results in a bond that is stronger then the material and water tight.

[Jeremy Greene]

A note from personal experience: Do not handle Tyvek for the first time in a small room (laundry or bath) without hearing protection. Very loud.

[Chris Chastain]

> Do not handle Tyvek for the first time in a small room (laundry or bath) without hearing protection.

Hah! No kiddin'.

I was almost embarrassed to use mine until it got broken in.

[Matthew Roberts]

Do you mind sharing which 3M spray adhesive is working for you?

http://www.shop3m.com/3m-aerosol-adhesives-v56tsbqkdk.html

[Author]

Posts