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MYOG: tyvek ground cover / bivy combo
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Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
"MYOG:Tyvek GCB" on 06/14/2008 16:20:56 MDT Print View

Eric, I will look into each of these suggestions. Thanks for taking the time to post your ideas/comments.

Stephen Lastname
(hootyhoo) - F

Locale: East TN
Re: MYOG: tyvek ground cover / bivy combo on 06/14/2008 17:30:14 MDT Print View

Has anyone ever flame tested that stuff. Like if you were cooking in the bivy and knock your alcohol stove over - would you be entombed in a melted cocoon of tyvek? I ask this because I remember a post on another board of a guy who made a tyvek tent for his kids and had them in there with candles and someone quoted the flame retardent specs and warned against open flame. I have a dwr top/tyvek bottom and love it. I rolled the tyvek up on the foot end about 12" to form an overkill bathtub and give better protection on that end since I sometimes slide toward that way. My feet seem to breath very well and the tyvek keeps the rain out. Works great. I had no problems sewing the dwr to the tyvek, but did not seal the seams.

Eric Fitz
(pounce) - F
Fire on 06/14/2008 18:54:36 MDT Print View

If you want/need fire retardant tyvek you want 2075D.

There might be some sprays you can use to coat normal tyvek. This might be a better approach since normal wear will probably cause the 2075D to be less effective. You can just respray.

Tyvek burns. Try it on a scrap so you know how it behaves.

Douglas Johnson
(Sponge) - MLife

Locale: PNW
Any updates on 08/10/2008 01:05:37 MDT Print View

I am wondering if there has been any progress on this project...this idea has some teeth, let's keep it going!

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
MYOG: tyvek grond cover bivy on 08/10/2008 05:28:46 MDT Print View

I will be posting an update soon with trip pictures of the GCB in use.

Brett Peugh
(bpeugh) - F - M

Locale: Midwest
tyvek on 11/27/2008 03:42:11 MST Print View

So what ever happened with this?

Keith Selbo
(herman666) - F - M

Locale: Northern Virginia
yeah, what happened? on 11/30/2008 20:24:37 MST Print View

Yeah, what ever happened?

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
MYOG: tyvek ground cover / bivy on 12/01/2008 08:19:13 MST Print View

I'm still very much working on this project. I've redesigned the cut so that I now have only one seam instead of two and I've incorporated a foot end vent (which I'm still refining). I found the tyvek bivy to warm for summer use but it has worked well this fall. I'm hoping the foot end vent will help by letting out some built up heat and increase air circulation. I have experienced no noticeable condensation, on occasions the interior face of the tyvek would feel damp, or moist, but have no noticeable moisture and my sleeping bag would be dry. I will try to post some new pictures of the redesigned cut and the foot end vent soon.
I've enjoyed seeing TT and others make use of this material with good results and reviews.

Edited by thomdarrah on 12/01/2008 08:28:32 MST.

Ralph McNall
(rumps) - F

Locale: SF Bay
rain on 12/08/2008 12:23:49 MST Print View

Have you had it out in any rain or heavy moisture like fog, and do you use it under a tarp or out in the open? Last weekend I started on a driducks bivy, but it was a toss up between that and tyvek ...

JJ Mathes
(JMathes) - F

Locale: Southeast US
Tyvek Bivy Update on 02/12/2009 15:51:06 MST Print View

Hi Thom- I was thinking about making a tyvek bivy for a one night trip. I've never used a bivy or tarp, my upcoming trip will be my first with both. I have the tarp, but no access to a bivy, don't want to spend the $$$ for one until I know if I'll like sleeping under a tarp.

Anyway I did a search and found your thread, after reading the posts I'm wondering if you've made a decision on the best adhesive

ALSO, will someone be kind enough to tell me how to PM Thom. I'm sure I have overlooked something in the process of trying.

many thanks

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
MYOG: tyvek ground cover bivy on 02/12/2009 16:54:14 MST Print View

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
(greg23) - M

Locale: Colorado
Re: MYOG: tyvek ground cover bivy on 02/12/2009 17:09:55 MST Print View

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

Nate Meinzer
(Rezniem) - F

Locale: San Francisco
Tyvek Bivy on 03/24/2009 15:03:07 MDT Print View

Have the BPL testers weighed in on this project yet?

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
MYOG: tyvek ground cover / bivy on 03/24/2009 15:10:23 MDT Print View

PM sent.

Nate Meinzer
(Rezniem) - F

Locale: San Francisco
MYOG Tyvek Bivy Review on 04/07/2009 20:30:10 MDT Print View

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:

Tyvek bivy

Tyvek bivy

tyvek bivy

tyvek bivy

tyvek bivy

tyvek bivy

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.


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.


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.

Edited by Rezniem on 04/07/2009 20:38:09 MDT.

todd h
(funnymoney) - MLife

Locale: SE
Re: MYOG Tyvek Bivy Review on 04/08/2009 06:42:59 MDT Print View


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....


Nate Meinzer
(Rezniem) - F

Locale: San Francisco
Tyvek Bivy Feedback -- Bonded Seams on 04/08/2009 07:01:30 MDT Print View

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.

Thom Darrah
(thomdarrah) - MLife

Locale: Southern Oregon
MYOG: tyvek ground cover/bivy on 04/08/2009 07:47:14 MDT Print View

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.


Edited by thomdarrah on 04/08/2009 09:02:48 MDT.

Joe Clement
(skinewmexico) - MLife

Locale: Southwest
MYOG: tyvek ground cover / bivy combo on 04/08/2009 08:04:39 MDT Print View

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

Nate Meinzer
(Rezniem) - F

Locale: San Francisco
MyOG Tyvek Bivy Review on 04/08/2009 12:25:00 MDT Print View

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.