Breathable Bivy Sack?

Looking for a breathable bivy sack for climbing trips in RMNP. Bought the REI minamilist last year but it's like sleeping in a Hefty garbage bag. Sure, it's waterproof, but lack of ventilation/breathability results in a lot of condensation inside the bag.

Can anyone recommend a bivy sack that either has better ventilation or improved breathability (even if that results in less water resistance)? I'm not interested in a tent.

thanks
Scott

Hard to get more ventilated than the Minimalist. It's not a full coverage bivy...your face is exposed/only covered by mosquito mesh. I'm assuming you weren't curled up down inside the bag???

RAB superlight bivy is made of eVent. I'm sure there are others. BD's are made out of their version of EPIC. I've had good experience with them.

I've used GoreTex and EPIC bivies and never had any REAL problem beyond the EXPECTED amount of condensation. If you are in a fully closed bivy sack, breathing into it all night...you WILL get heavy condensation. No big surprise. Otherwise I've never had problems on the short trips I use them on.

I've had good experience with them. I've used GoreTex and EPIC bivies and never had any REAL problem beyond the EXPECTED amount of condensation. If you are in a fully closed bivy sack, breathing into it all night...you WILL get heavy condensation. No big surprise. Otherwise I've never had problems on the short trips I use them on.

Yep, I second this.

I have and love the OR Alpine Bivy (Link at REI). It's awesome. I used it on Rainier last year and have used it several times since then. Great, great product.

The OR alpine bivy is pretty good, i'm 6.5 though and its a bit tight for me, never slept well in it when i had to close the lid. Black diamond makes one with a lot more head space that looks great, anyone used that?

For summer nights in RMNP I use something similar to the MSR E-Bivy (friend sewed it, so no brand). It has a water resistant, breathable top (maybe DWR treated?), waterproof bottom, and exposed face. Only 8oz and works well for "under a boulder" situations where you may get some blowing rain, but won't be sleeping in a downpour.

Well it is certainly possible that my problem is either user error or I simply sweat too much while sleeping. I keep my head up at the mesh level, but prefer to sleep very warm, so it is possible I just need to get used to sleeping cooler or using a lighter bag. In the morning, the foot of my bag is essentially soaked and the rest of it is damp. I've also read a bunch of similar complaints regarding this particular bag. Seems like way too much condensation, but maybe I need to just work on my system a bit.

eVent fabric will make a big difference. Significantly more breathable than the other fabrics I've used.

303scott wrote:Well it is certainly possible that my problem is either user error or I simply sweat too much while sleeping. I keep my head up at the mesh level, but prefer to sleep very warm, so it is possible I just need to get used to sleeping cooler or using a lighter bag. In the morning, the foot of my bag is essentially soaked and the rest of it is damp. I've also read a bunch of similar complaints regarding this particular bag. Seems like way too much condensation, but maybe I need to just work on my system a bit.

The REI bag has a waterproof, not-particularly-breathable membrane. Either switch to something water-resistant, or something waterproof but more breathable (like event, as mentioned).

event ... i own and use an integral designs micro bivy

I really like my blackdiamond bivy, yellow, with the one pole to keep the bivy off your face. Has mesh for breathing zone when its not raining.

So here's the technical info I recieved from REI regarding their bivy

"This bivy has a waterproof coating rating of 1500mm. We do not offer a breathability rating for our bivy sacks because it's presumed you'll be stationary and exuding minimum body vapor when inside the bivy."

However, I wonder if they dropped a zero on that number since the industry base appears to be around 10,000mm....

Here is a good site that lists breathabilty/waterproof ratings for a variety of fabrics: sierratradingpost.com/lp2/w…

REI's is not on there. The eVent fabric seems to get excellent reviews, so I think I will check that out. Thanks to everyone!

If it isn't too late, sierra trading post has the Rab alpinist bivy right now, eVent and whatnot

Vapor barrier liner? Works well to keep you warm and your bag dry.

VB liner in teh summer...ewwww

eVent crushes standard wp/breathables in breathability in my experience. I use the ID Micro Bivy and like it a lot. I've had Bibler and OR bivy sacks, but they don't measure up to ID+eVent in my opinion.

Ended up getting a RAB Ridge Raider made with EVent. Test drove it in RMNP last weekend. Despite the fact that it was quite hot at night (40 degrees)and I roasted in my 0 degree bag there was virtually no condensation inside the bivy. An amazing improvement over the REI bag (and three times the cost)....