Bivy Sack

A simple Bivy Sack design for ground dwellers. There is no lighter shelter than a Bivy Sack, so if this sleep system works for you it is a great way to lighten the load significantly.

18 thoughts on “Bivy Sack

  1. I spent many nights in the cheapest bivy that REI no longer sells. A couple of thoughts about this design. First of all, I love sleeping in my bivy sack, tents can feel isolating and they have endless odd little noises. A bivy is cozy, minimal, easy, lightweight. Definitely make a bivy. This one looks pretty good. I’d sleep in it. 1. The mesh area seems large. My bivy has a smaller mesh opening, and came with a warning to leave the zippers open a bit for breathing. In my living room, the bivy was stuffy. Outside–not in the least. 2. Rain fly. Try not needing one. I thought I had some ideas that would work….. after all the mesh on my bivy, like this one, is on the top. First night in my bivy, Mt Kitadake, 10,000 feet, blowing rain. I just turned the opening away from the rain, another night I turned it almost upside down to keep out the rain. I’d thought about this problem for weeks– outside in real conditions, the solution was immediately obvious. (Occasionally I got some water inside, but the air mattress kept it from reaching my sleeping bag) 3. The way I liked to use my bivy is sleeping bag and air mattress inside, then in the morning I just let out the air, loosely rolled it all up and tied it to my pack. I could be packed-up or set-up in two minutes. 4. I’d suggest a ‘fly-flap’ on either side of the opening, maybe 12 inches, so that if you roll it over to one side or the other it’ll block the vertical. Also the mesh shouldn’t be as wide (I can’t exactly picture the final result here.) To do the turn-away-from-the-rain-thing, you need not just the bottom but the sides and some of the top to be a ‘bathtub’ The fly-flap doesn’t have to go all the way across, and it could have a mitten hook on it as well. (mitten hook-great idea. My ‘pole’ is a hiking pole jabbed in the ground. 5. More shoulder space for gear stashing, and wiggling it around to the side. I never knew what to do with my smart phone earbuds and eyeglasses–I wound up placing all kinds of stuff on the upper sides and above my head. I did wind up treating like a tent. Before I’d sleep I’d have it zipped open, rest on my elbows reading, or I’d be slightly out of it making coffee with my jetboil. Maybe another mitten-hook at the toe end, to allow air circulation. Zipper along just one side? I wouldn’t have a problem with that. Also taller is better, taller people and above your head is another place to stash stuff–like bear spray. I think the really nice bivy sacks available now are simply too heavy. My Big Agnus 2 person weighs 3 pounds, these bivys weigh 2 pounds–that’s not a big difference considering all the space you get, and the tent fits two people.

    1. Great thoughts Will. Thank you! One point though at the end there – this Bivy weighs 7.5oz, not 2 pounds. I’d add another 6oz for a proper rain fly with it, but still well under a pound.

  2. I’m getting ready to make one of these with an additional 12″ length and maybe a little wider, not sure yet. One question I had was if you need to add an inch or so extra to the Netting and Top fabric length for the Flat-Felled Seam where these two pieces attach?

    Thanks for any help!

    1. Hey Bryce. The total length on this is 78″. The top and bottom flap in the diagram come up 5″ at the top and 6″ at the foot, so the “top” piece becomes longer than it looks. Still, not a bad idea to add some length. I’d say sure, go ahead and add a bit for seams. I would do my final seam at the foot end, where the top piece meets, leaving some extra to make sure it all fits together there properly and trim off any extra after. Hopefully that makes sense.

  3. I just completed this design. I am 5’10” and 155 lbs and I do not fit in this. I recommend making this a foot longer and a foot wider, roughly speaking. This is not a bivy that can accommodate a pad either. If you are 5’6″ or shorter this is the design for you. Consider this a good base design that needs significant revisions to allow for people of average/tall height and if you want to be able to put a pad inside.

      1. It’s my first bivy. It was made in 2013 to got skills and to try bivy system. Used cheap Tyvek soft “membrane” material (about 1.5 oz), 0.7 oz netting and #5 zipper. Total 220 grams.
        It lasts about 120 trail days and need to be replaced )

  4. Yes, pictures of finished bivy with gore-tex top and netting. That is exactly what I am planning on doing. I don’t want to sufficate, but want extra ‘rain’ protection, but the option to use netting/bug proof. I’m very allergic to most any bug bite; but want to staydry, warm and cozy if rain comes. I plan on taking a small tarp to pitch for super foul weather for added protection and a place to cook and keep other things dry; alternatively small tarp can be used as shade also. I was planning on making a 9×9 tarp–but that does not address my design need of bug protection. I know no tent/tarp/bivy is the perfect solution to all conditions, but in trying to keep weight down; bug protection; rain protection; this bivy w/ gore-tex upper body protection might be my best-of-all-worlds approach. I will not be using this in snow (i hope). Also, I plan on cutting a very old sleeping high density foam pad to fit the inside of the bathtub bottom. I don’t have the $$ to buy all the UL stuff available now. I started backpacking in the 80’s; trying to get back out their after many health issues. Bivy might be one of the best ways I can shave lbs from my pack. Would really appreciate some pictures–if anyone is willing to share. I plan on making a scale model w/ zipper before sewing a full sized (scale model about Barbie doll sized to tweak design and, so I can give to my grand-daughter to play with). When I get that far, happy to share pictures/design. I’ll use treking pole to create post to pull netting or gore-tex top off face–and/or pitch tarp as needed. Also, the bivy will be ground cover when just cowboy camping (warmer weather) and I’ll just throw my sleeping bag on top. If weather gets ugly at night, just need to slip bag inside bivy. Thanks in advance for any help on the design of bivy w/ net or gore-tex top.

  5. Thanks for the plans for this project. I just built this, but added an additional flap of gore-tex to cover the mesh for optional rain protection. Your instructions were great. I am not much with a sewing machine, but was able to complete the project in 4-5 hours of work.

    Comment for tall folks: I’m 6’2″ 185 lbs, and I would have made this about foot longer, and maybe a foot wider as well. I “can” fit in this, but it is really too small to be practical. I’ll likely give this to one of my smaller friends, and built myself a larger one.

    Thanks again for the good plans!

    1. Great thought Casey – for a roomier bivy, add extra length. I’m 5’10” and this one works for me, but you’re right, it’s not super roomy, and any taller would make it too small.

      To increase the length, just add the same length to the 60″ section of the bottom and the 41″ section of the top piece. That’s the easiest way to increase the length. A bit less simple would be to increase the netting area (do it at the bottom part).

    2. Casey, how did you design the goretex flap to cover the mesh for rain protection? And how does it attach to the bivy? I’m concerned with keeping rain out but keeping the goretex flap in place.

  6. I can’t type the character, but in he #2 instruction there is a light green A symbol. That symbol is shown in the illustration and is where you start your sewing (from the inside corner – the only inside corners in the entire plan). The light green arrows show where the sewing goes from that point.

    The illustration is attempting to show that there is an 8″ tall flap at the head end, and a 10″ tall flap at the foot end. For the head end, fold the fabric together at the inside corner and sew together, following the edge – but don’t sew all the way – leave the last inch of that 8″ flap free. That is so you can sew it to the zipper attached to the bug net. Do the same for both sides of the head end, then do the same thing with the foot end. Folding the fabric together at the inside corner, sew the perimeter up to the last inch of that 10″ flap. Again, the inch left is so you can sew it to the bottom end of the top piece.

    Basically what you are doing is forming a bathtub style bottom, you’re giving the head and foot end some height coverage to better keep out the elements.

    Hope that makes a little more sense.

  7. I’m not quite sure that I undersand the instructions in #2, sew the head and foot end flaps as far as they will go. Are flaps and sides folded up and sewn together? I tried making a paper pattern to simulate and this is all that I could come up with.


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