Using bivy bag with a sleeping bag?

I am talking about down sleeping bags used in colder winter temperatures (zero and below °C). So there will be no rain here (maybe snow or wind). Any you have a bivy bag (maybe event material or similar).

The question is, would you use bivy bag in normal circumstances (no snow or wind)?

Would bivy bag provided few more degrees of warmth, if necessary? The purpose of having bivy of course is not to (possibly increase sleeping bag comfort temperature?), but in case of snowy downfall of a kind, or strong wind (as mentioned above).

On the other hand, if bivy bag would not be sufficiently breathable (deepening on outside conditions) and would cause a lot of condensation and made a mess of your sleeping bag, obviously you would not want to use it then.

What are your experiences using a bivy bag and condensation issues in winter time?

Ante Predovic 1 wrote:
What are your experiences using a bivy bag and condensation issues in winter time?

I typically use a bivy to add a little warmth to winter camping. I've only had condensation issues when weather has forced me to pull the bag over my face. No breathing in the bag = no condensation problems in my experience.

If sleeping without a tent it would help cut down on wind since even a really slight breeze would make a sleeping bag much colder.

In a tent any benefit in warmth would be lost with condensation. Depends on how dry it is where you are though. If higher in the mountains then it’s probably dry enough that condensation won’t be an issue. If you are ski touring down below the tree line then it could be really different. 

I have used my bivy in Appalachian Trail shelters during winter, and as someone said above, condensation is not an issue unless you have to close yourself inside. It definitely adds a bit of warmth to the system but I couldn't guess at how much. . 

I’ve used bivy sacks on winter storms on el cap and I have been hosed by the condensation but A tip Chongo gave me before I went up on that wall helped a lot. Take a synthetic or wool blanket and use it as a Mid layer in between your bag and your sack. On the dry but cold nights you get a bonus liner in your bag.

I use a bivy with my sleeping bag pretty regularly and similar to what Hayden mentioned I typically throw a fleece on top of my sleeping bag and inside the bivy. Had a couple mornings with condensation but always with my head inside and at least partially zipped

As others said, if you aren't breathing inside the bivvy condensation isn't an issue.  How much warmth you get depends on the bivvy.  A "regular" Gore-tex bivy will give you a little warmth but it's designed to keep you dry and block wind, it's not really about insulation.  BUT when you look at things like the SOL escape bivvy or, what I have, the 2go Systems Trifecta v3?  Since they have the reflective inner liner you get a fair amiuntnof extra warmth because you have now, essentially, put your sleeping bag inside what amounts to a reusable emergency blanket.

I find that, as long as I wear a fleece and neoprene balaclava (with my bags hood sinched tight) the Trifecta works really well taking a 20 degree bag, comfortably, quite colder than you would think and thanks to the balaclava I had no need to pull the bivvy over my head and risk condensation issues.

wisam wrote: Depends on how dry it is where you are though. If higher in the mountains then it’s probably dry enough that condensation won’t be an issue. If you are ski touring down below the tree line then it could be really different.

Condensation inside a bivy sack is going to depend almost totally on your own sensible/insensible perspiration and respiration. If you are using a breathable fabric  bivy, this will help somewhere between a fair amount and not at all depending on whether the outside conditions are conducive to the bivy breathing. I would use it outside. It will be a few degrees warmer and you can keep your head in or out depending on the weather/bugs. Another thing to consider is how tight the bag is. If the bivy bag compresses the loft on your sleeping bag, its going to likely be colder rather than warmer, unless it is windy.

Pretty much yes to all your questions.

Condensation should only be a problem if you're spending a lot of nights out and the temps remain cold during the day. re unable to dry it out.

Just make sure you use a sleeping bag. Had a recent adventure with a buddy and no sleeping bags just a bivy sack we shared and froze our god damn asses off in a snow storm with constant 40mph+ winds and sub 0 temps.....

It's the master gumby D:

gumbie gene wrote: It's the master gumby D:

Lol exactly fellow Gumby