Condensation Inside Bivy Sack

[SteveAndTheCrigBoys]

I'm used to the condensation in my tipi by now but was looking forward to my Borah bivy helping keep my quilt dry. Well I woke up the first night to it being way more damp than it ever got without the bivy. And the same thing the next night too.

Do these bivys actually trap moisture in? Any tips on how to prevent this?

 

[Poser]

I have not used a Borah bivy so not very familiar with the top sheet fabric, but, I have used bivy sacks extensively. In order to push moisture though the breathable membrane, you need a pretty good temperature differential between the inside of the sack and the outside. You’ll get a widespread of information here, but the short of it is that it needs to be pretty cold out to push moisture through. If not, just leave your bivy sack mostly unzipped.

 

[SteveAndTheCrigBoys]

Yeah this was mid 30's outside and snowing. 0 degree down bag so with my pad and the loft of the bag there wasn't much of an air gap from the quilt to the bivy top.

 

[Poser]

Yeah this was mid 30's outside and snowing. 0 degree down bag so with my pad and the loft of the bag there wasn't much of an air gap from the quilt to the bivy top.

Probably not going to get much airflow inside your bivy, it’s more about letting moisture easily escape if you don’t have the conditions to push moisture through the membrane.

 

[justinspicher]

I had quite a bit of condensation on my last hunt between my bag and bivy. I’ve decided that I won’t be using a bivy inside a shelter anymore.

 

[Tim in Wa.]

I've tried a bunch of bivys including a Borah. Regardless of conditions my bag is always wet in the morning

 

[rclouse79]

I got a custom one made from Borah bivy with a six inch wide strip of big netting running down the middle. As far as I know that is the only solution. It is good for a tick barrier and splash protection when under a small tarp. It wouldn’t work as a stand alone shelter. I bought a regular one for my son and used it without a tarp this fall. I woke up soaked in the middle of the night. I pulled my bag out of it and slept on top the rest of the night. I was cold after my bag got wet.

 

[Hunt_Jefferson]

I’ve got a handful of nights in a Borah Bivy and a 20* El Coyote quilt. Friday it got down to 35* with fog so lots of moisture in the air. I noticed a lot of condensation at the top 1/3 from my breathing, tended to scoot down away from the netting at the top as it got cold. But the quilt was relatively dry in the bottom 2/3 of the bivy.
Note I was under a large enclosed Borah tarp with a ground barrier, YMMV. Tarp was very wet inside and out.

 

[Legend]

I had issues with several brands. Bought the black diamond and everything was solved. Ot has really weird material unlike any else i have seen.

 

[JDBAK]

I had issues with several brands. Bought the black diamond and everything was solved. Ot has really weird material unlike any else i have seen.

Is it the old Bibler versions made with “ToddTex”? (named after Todd Bibler, came in Lime green or bright yellow and feels kinda like paper towel on the inside)

I have old Bibler tents and a Bibler tripod bivy made before Black Diamond bought them out. I’ve been impressed by their breathability and waterproofness. I’ve heard the lighter BD tents with different material don’t breath nearly as well.

 

[tdot]

I also have one of the Hybrid Borah Bivy's. They have enough protection on the sides and top to offer splash protection if you're under a tarp, but no-see um netting in the center for the full length of the bivy, plusa bunch around the face. I personally think it's the perfect bivy for use under a tarp or floorless shelter. You have to ask Borah Bivy about them, I don't understand why they don't list it on their site.

For the OP, using a 0 degree bag in above freezing temps likely would have led to excess persperation from you. Which wouldn't have helped the situation. I personally can't be in a 15 degree bag if the temps are above freezing. I actually end up being colder due to the sweat.

 

[Legend]

Is it the old Bibler versions made with “ToddTex”? (named after Todd Bibler, came in Lime green or bright yellow and feels kinda like paper towel on the inside)

I have old Bibler tents and a Bibler tripod bivy made before Black Diamond bought them out. I’ve been impressed by their breathability and waterproofness. I’ve heard the lighter BD tents with different material don’t breath nearly as well.

That is the stuff. I have both the bibler and the black diamond. That toddtex fabric is awesome.

 

[JDBAK]

That is the stuff. I have both the bibler and the black diamond. That toddtex fabric is awesome.

Cool. That stuff has worked really well in some ridiculously wet conditions for me.
I could save a good pound with a different bivy, but not sure it’s worth it.

 

[Dos Perros]

To combat condensation inside your bivy, you need to add a bivy inside the bivy. Double bivy.

 

[Beendare]

Delete

 

[Moserkr]

Never had an issue in my borah bivy, but ive heard of the issue from others too. I guess burning a stove constantly eliminates the issue? If its any kind of wet out, stove is burning. If its cold and dry, no issues with condensation ever.

Saw in another thread where 1/3 of a guy’s bag in his bivy was dry and 2/3 was damp from condensation. The dry side was next to the tipi wall and got ventilation. Poor ventilation leads to condensation period.

You also mentioned your bivy was tight so that means no breathing room in it. Mine is loose over my bag, ordered the biggest bivy available from borah even though Im average sized. Im sure that helps it breath with wiggle room.

 

[Superdoo]

Here are some photos of the "vented" borah bivy. It works great! Cost $20 extra.

https://imgur.com/a/aKEFe

Here's a blog post with more info: http://cesarandthewoods.blogspot.com/2016/02/borah-gear-bivies-double-reviews-long.html

 

[insanelupus]

One of the things I've found with floorless tents, relative humidity plays a big part in the condensation issue. I'm guessing bivvy same thing. Been looking at the vented Borah myself.

 

[SteveAndTheCrigBoys]

Well I bought the bivy to help keep my bag dry but it seems like it was easier to do that by just keeping it away from the tent walls and putting my rain jacket over it. Might be a bivy posted to the classifieds here shortly...