Borah Bivy Modification

About 10 months ago I placed an order for a side zip Borah Bivy. As I noted then, the entire transaction went very smooth. John was great to deal with, and the bivy’s craftsmanship is top-notch; I couldn’t ask for more. However, after using the bivy a few times, I came to realize that choosing M50 for the top material may not have been what I thought I wanted. IME, the M50 is not very breathable at all and traps more moisture inside the bivy than I would like.

Now don’t get me wrong, I still love the Borah Bivy and feel comfortable in recommending them to others, however, I learned that the choice of material should be based on more than just weight savings. After I realized this, I started weighing my options for ways to either improve the bivy’s breathability, or to just sell it and get another one with different materials. While thinking about things, I wondered about adding some mesh to the top of the bivy. In theory, this would allow much of the moisture to escape, while still allowing the sides and foot end to be water-resistant…

In my research, I also noticed that Cesar Valdez (from Cesar and The Woods) also had a Borah Bivy with M50 for the top (although, he had the cuben floor… lucky dog!). So I messaged Cesar and asked him about his experiences with his own bivy. He responded back and told me that he also noticed a great deal of moisture retention within the bivy and was modifying his own bivy with a piece of mesh on the top!

This was great to hear that Cesar was actually in the process of making this exact modification, so I decided to wait and see what his findings were. Then, just soon after, he posted his own findings, and they were good!

Now, I will admit, I do have some limited experience with my thread injector, but not much, so I was a bit nervous about making this modification myself. I wasn’t sure if I wanted to chance cutting up my bivy and ruining it. However, I did go ahead and order a piece of scrap noseeum mesh from Quest Outfitters… you know, just to taunt me…

And it worked… because yesterday I decided to go ahead and give it a go…

Simply put (and as seen in the video), I cut a rectangle approximately 8 & 1/4″ wide by 41″ long from the center of the bivy, next I pinned the mesh to the edges of the fresh-cut M50, and then simply sewed the mesh to the M50.  In doing it this way, the M50 has a raw edge on the outside, and the mesh has a raw edge on the inside (if this makes sense). In the end though, I am actually quite happy with the way it turned out. The only concern I have is if the M50 starts to fray along the edges… only time will tell if this will be a real concern though. Either way, I feel confident that it will hold up just fine for me to see how I like it with the mod… at which point I may decide to order another Borah Bivy, but this time with a cuben floor, and likely in a wide to better accommodate my large size XLite.


Other than this, I had also been thinking about relocating the pull out that comes standard on the mesh head net.  To be honest, I have been leery of the pull out being sewn to the mesh… but to be fair, there has not been any issue with it thus far. It just seems to me like it would pull out of the mesh fairly easy though, and tear the mesh. So, I had been thinking about adding a tie out to the M50, located right below the zipper.

So, I grabbed some 1/2″ grosgrain and did just this. I thought about sewing the loop to a piece of material, and then sewing that material to the bivy, which should add a bit more reinforcement, but in the end I took the easy way out and just sewed the loop straight to the bivy.


I do feel a bit more comfortable about the tie out being sewn to the M50 material instead of the mesh, although, I will admit, I still use a piece of 1/16″ shock cord on the pull out to help absorb shock. As well, I also found that by having the tie out attached to the M50 may ease ingress/egress from the bivy. By guying the shock cord out, the bivy will stay opened up, however, it doesn’t help to pull the bug net off of my face like the original tie out point did. So, rather than removing the original tie out, for now I will leave it be and see how it all works out…

The last thing worth mentioning is weight. The noseeum mesh that I added is spec’d at 0.87 oz/sqyd (per Quest Outfitters), where as the M50 is spec’d at 0.69 oz/sqyd (per Thru-Hiker), so naturally, this replacement added a tiny bit of weight. When I first got the bivy, it weighed in at 5.7 oz for the bivy only. Since then, John has added tie outs at the foot, and now I have added the above modifications. As well, I store the bivy inside a cuben fiber stuff sack (from ZPacks of course) and have added a piece of 1/16″ shock cord with a mitten hook and tiny cord lock (to adjust the length). With all pieces mentioned, the total weight comes to 6.2 oz, which is definitely not the lightest, but it is acceptable.

I gotta say that I am glad I finally took the chance and made the modifications. The M50 does a great job as far as water resistance is concerned, and now the mesh window should help alleviate the M50’s weakness, breathability. I also want to say one more time that I appreciate the feedback that Cesar has provided me, and considering his results, I am confident that this will work pretty good…

Thanks for stopping by!


Disclaimer: There is not much to say here… I bought the bivy, I bought the mesh, I made the modification. I am not affiliated with any of the companies listed above, nor have to write about their products. I do give credit to Cesar for this mod though, as well as for my inspiration to just do it!

About Stick

My blog is essentially a record of my hiking career. Through it, I, and others, can see how I have evolved from a heavy weight backpacker, to a smarter, more efficient, lightweight backpacker. Through the use of video, still photos, and of course writing, one can see my progression, as well as check out some of the places I hike, and not to mention some cool, lightweight gear options. For me, my blog is a journal, but for others, I hope that it is an interactive learning tool to aid them in their own progression towards lightweight backpacking.
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17 Responses to Borah Bivy Modification

  1. John West says:

    Hi Stick,

    John here from Borah Gear,
    Great job on the modification, looks really good!
    Singeing the raw edges of the M50 will prevent it from fraying in the future.
    As you have noted, the M50 can have issues with condensation when not used in a dry climate. The material has an excellent DWR coating which makes it nearly waterproof, but this makes the fabric lack in breathability. Because of this, I rarely recommend it to people, and probably about 85% of orders these days are M90.
    M50 is still a great choice if you live somewhere that isn’t humid, and I have friends down in AZ and CO that have never had any issues with it. However living in the humid northwest, I personally still stick with the M90, and with 60+ nights in the field with the M90, I’ve never once had condensation issues.
    Anyways, once again, awesome job on the modification, and I love reading the reviews you post on here!


    • Stick says:

      Hi John, and thanks for stopping by and sharing! I thought about running a lighter across the raw edge of the bivy and should have done it to begin with… it may be a bit harder to do now that the mesh is sewn next to it… I may pull it out and see what I can do with it though.

      As for the M50, I agree, for drier climates, it is likely more acceptable, but for me here in the Southeast, it just doesn’t work for me. I do feel like the mod will help it a bit more though… As for the M90 though, I have heard a lot of good things about it, and wish I had went with it to begin with…

      Saying that, I would like to get another one from you sometime soon hopefully… this time though with a cuben floor & M90 top though! 🙂

      Thanks again for stopping by!



  2. ” I learned that the choice of material should be based on more than just weight savings.”

    Chad – nice mod. Yeah, it takes a while for the weight vs comfort thing to sink in. Next thing you know you’ll add 5 more pounds back to your gearlist because you like staying dry, warm, etc. 🙂


    • Stick says:


      Yeah, I am pretty much hard-headed & like to learn things the hard way sometimes… but, it’s how I learn what works and doesn’t for me. Hopefully though others will learn from my experiences…

      Now, as far as adding in another 5 lbs… only on trips in the “winter” or with my wife and kids! 🙂

      Thanks for stopping by.



  3. Jeffrey Sims says:

    Nice job!! I received my Borah bivy last week and took it out over the weekend. I was hesitant to go with M50, and John actually did recommend the M90 (I spend most of my time in the Sierra Nevada) so I went with a side zip cuben floor, M90 top and I am happy to report no condensation. I still need to spend additional time in it to confirm it for the long run but initial markers are good. I ordered it extra extra long as I am 6 ft 5 and I also asked for extra wide as I am an active sleeper. with the included cuben stuff sack everything weighs 6.15 ounces on my scale.

    I like your MOD, and if I end up with condensation challenges I will take your lead and do something similar.

    Thank you for continuing to push the envelope, and share your findings with the rest of us.



    • Stick says:


      That is awesome! I would like to get another bivy from John, almost similar to yours, I just don’t need the extra length, but the width would be appreciated with the large XLite.

      Anyway, I am looking forward to hearing more about the M90 & breathability…

      Enjoy your bivy!



  4. Nice Mod and good work!


  5. David Sullivan says:

    Stick – Reminds me of when I sat on the roof of my house for three hours before I could get up the nerve to cut a hole in the roof to drop a stovepipe down through to a wood burning stove. You seem to have found a solution to a common problem of condensation in the Borah Bivy. Your workmanship on the sewing machine looks pretty good, but time on the trail will tell whether or not it will hold up. I’m betting it will.


  6. Dave Collins says:

    Nice writeup and tutorial video Chad. Your info will be very helpful to those of us that need more breathability in our bivys. I really like your solution. Thanks for sharing!


    • Stick says:

      Thanks Dave! Glad that you liked it. Gotta give the credit to Cesar for this one though.

      Also, I read your post today, funny that you posted about cutting up gear and I posted this… 🙂



  7. Greg Williams says:

    I took my brand new side zip Borah Bivy (M50 long and wide) on an overnighter last month on Mt Rainier Eastside Trail. I found that I had a ton of condensation on the inside when I woke up in the morning. I thought that it was due to my pad sliding a bit inside hat caused my head to slide below the mesh on the head end. I’m glad to see that wasn’t necessarily the case. Thanks for having the courage to cut up an awesome piece of gear and make a great improvement. I plan on doing the same thing when my sewing machine gets repaired and my sewing skills improve, or John makes this an option and I’ll have him do it! Thanks!



    • Stick says:


      Yeah, I am pretty much feel like M50 is really not very breathable at all… they say that M90 is better, so if I were going to be ordering another one without a mesh vent, I would go with M90 I think. However, I have a feeling that this mesh window will really take the bivy to the next level… at least that is my hopes… 🙂

      Anyway, good luck with your mod, and feel free to post back and let us know how it goes for you. Feel free to include some photos if you would like… the more feedback the better!




  8. Don Milligan says:

    Scary project but you did a great job. This was my first viewing of someone actually making the mods with a thread injector, thanks for taking the time to give us an example of the process.


    • Stick says:


      I agree, I was a bit concerned, especially after some of my last DIY projects… But I gotta say, this one went better I think. Anyway, glad you enjoyed the video, and thanks again for stopping by!



  9. Kevin says:

    I have the same style Borah bivy with M50 and have wanted to do this mod. Cesar’s turned out nice and like you I was hesitant to do surgery on a new piece of gear.
    Well after two successful mod’s I may have the faith to chop into mine.
    I like the looks of the netting and tie out.

    Thanks for the good info. Time for me to prep my wife for a Saturday gear mod session.
    She just loves when I see new ideas on MYOG!


    • Stick says:

      Haha… too funny Kevin! I hear ya though. I usualy get the stuff together, but then have to wait for the bug to kick in to actually do it. Last night was totally unexpected… I just got to thinking about it and went for it. Even as I was making the video though, I wasn’t sure… But I wanted to record it just in case I went through with it… and I did!

      Anyway, good luck with your mod. As I mentioned, the only thing I would have any concern about is the raw M50 edge. If you can hem it first, it may be better. I just tried to make the straightest cut I could though and am hoping for the best. I think it will be ok for a good long while though… at least I am crossing my fingers that it will be! 🙂



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