Bivy in winter vs switching to sleeping bag

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Home Forums General Forums Winter Hiking Bivy in winter vs switching to sleeping bag

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    Nathan H
    BPL Member


    I’m looking for some advice on how to add some warmth to my winter/snow sleeping system. I’m a cold sleeper, and I suspect the lowest temp I’ll encounter is 15-20F.

    Here’s my current set-up, which works, but it’s a bit cold at times. I wear all the clothes listed, and I eat before I sleep.

    • Locus Gear Khufu eVent-DCF
    • Katabatic Sawatch
    • Nemo Tensor Insulated
    • Thermarest Zlite
    • Goosefeet down booties
    • Patagonia Thermal Weight baselayer(top/bottom)
    • Feather Friends EOS Down jacket + hood
    • Zpacks possum gloves
    • Zpacks fleece beanie

    I was wondering if adding a Bivy would help without adding too much weight/bulk. Something like the borah argon bivy, or katabatic bristlecone, or mld superlight.

    One thing I worry about is condensation. I current get some condensation inside the walls of my Khufu (even tho it’s eVent-DCF), and it’s really annoying. My footbox touches the walls of the tarp a bit, and there’s always condensation around my mouth area. I typically pitch my tarp all the way down to the snow to prevent draft. I suspect this is adding more fuel to the condensation issue.

    If I add a bivy (I won’t zip up the head area), will this move condensation to the outside of the bivy? Or will it be between my quilt + bivy? Will this add some draft protection and maybe add 5 degrees of warmth?

    Maybe I should just switch to a FeatherFriends winter bag, and it’ll keep my warm and let me open my tarp up a bit to get some wind circulation?


    Paul McLaughlin
    BPL Member


    If you are already inside a shelter, a bivy is not a weight efficient way to add warmth, although if you have draft issues using a quilt in cold weather, a bivy can help with that to some extent. A warmer quilt/bag , something with maybe 3 oz more down, will add more warmth than a bivy for less weight.

    Another thing you might try, is a warmer hooded jacket, or even just adding a separate down hood in addition to the EOS jacket – but the added hood will only be efficient if sized to go over the jacket hood.

    Nathan H
    BPL Member


    I see.

    I feel like I’m right at the edge of being fine with my current setup vs being slightly cold. I was hoping to make the minimal adjustment to get this setup to work. :(

    Edward John M
    BPL Member


    Insulated pants? A thicker pad? The RidgeRest Solar is warmer than the Z-Lite

    I found I was much warmer when I swapped to a long wide pad system but I couldn’t get used to a quilt in winter and changed back to my sleeping bag

    BPL Member


    Before “fixing” anything else, consider a warmer pad: either a second pad or an inflatable with a decent R value (like the Thermarest Xtherm or similar). Biggest heat loss is to the cold ground you sleep on – insulate yourself from that heat loss if you find you’re cold. No bivy, sleeping bag etc can fix that.

    Or sleep in a hammock and get off the ground altogether…..

    Nathan H
    BPL Member


    Is the nemo tensor insulated + zlite not enough for snow? Those two together should have at least an r value of 5.5

    Edward John M
    BPL Member


    Well I use a S2S Comfort+ plus a RidgeRest Solar plus a 4mm thin PolyCro/ foam/RFL on snow

    Combined R value  over 10

    I see the Solar is not listed on the Thermarest site anymore, the SoLite isn’t quite as thick or warm but close

    Bruce Tolley
    BPL Member


    Locale: San Francisco Bay Area

    @ Nathan

    I  used an old BPL branded bivy manufactured by Oware Gear with a water resistant top when snow camping under my MLD Duomid. I agree with Paul’s comments about about the bivy not adding much insulative warmth.

    But the bivy does cut down on drafts, enables me more easily to mitigate snow and frost from getting on my sleeping bag, and provides a place for me to store extra clothing and other items at night.


    Tjaard Breeuwer
    BPL Member


    Locale: Minnesota, USA

    A bivy will certainly add something to a winter tarp system. it certainly helps prevent drafts, and It might allow you to raise (one side) of your tarp a bit, helping to reduce condensation. But, this will also make things colder.

    If equipped with a wpb foot section, it can also help with feet brushing tarp.

    i would say, maybe your first step should be a thin Apex over quilt. This adds warmth, and moves the dew point out of your down quilt. It also provides some resistance to brushing the inside of the tarp.



    Did you watch RJ’s masterclass on inclement weather backpacking? He discusses the over quilt there(al though it cetainly has been discussed on BPL many times before).

    Mark Verber
    BPL Member


    Locale: San Francisco Bay Area

    If you were using a more open tarp or if you are an exceptionally restless sleeper, a bivy would be a big help at preventing drafts, but if you are pitching the Khufu to the ground and sleep calmly, a bivy won’t be a big warmth boast.

    My first question would be is your pad warm enough?  After you settle in for the night do you feel cold creeping in from the bottom?  If so, swap the Nemo for a warmer pad.

    If you aren’t feeling a chill from below, then you need something warmer on top. You could add / change… warmer jacket, an insulated vest, a thick down baklava (love mine), a second quilt, etc, but I would suggest that if you regularly do winter trips, go for winter oriented bag or quilt.  Choice something that by itself is comfortable for your “normal” winter conditions, and uncomfortable (but “safe”) in the worse case, and comfortable in worse case when used with your clothing.

    I suggest this for two reasons.  (1) It’s simpler and less fiddly… less decision fatigue when planning a trip.  (2) For cold trips it will be lighter than multiple items brought specifically for sleep.  Adding down to a bag / quilt is at least 2x more warmth / weight than adding an additional layer which has  insulation + shell,

    The last thing to consider is how quickly you go from active to in your sleeping system.  According to some old charts , at 0F you need to be surrounded by a loft of  2.5″ to sleep,  1.3″ doing light work, and  0.35″ when active. If you don’t lounge around outside your bag, then it’s unlikely your clothing is going to be a significant enough boast.

    Finally, remember that people’s metabolism varies widely… go with what works for you.  When I purchased a WM Versalite in 2003? it was “rated” for 20F.  I leave it unzipped until it’s below 0F or I roast.  My wife thought it was perfect at 40F.

    Random thoughts about sleep systems

    PS: while a quilt is warmer / weight than a bag… I found that when it’s below around 20F, there is something psychologically comforting burrowing into a puffy bag… it “seems” warmer than a equiv quilt.

    PPS: if you were looking a colder conditions I would think about a vapor barrier.

    Nathan H
    BPL Member


    @Tjaard, I was debating whether or not to purchase that class for this exact reason. I actually used an apex overquilt last season, and that helped with the condensation, and definitely added a lot of warmth. However, I eventually got tired of fiddling with quilts in the winter and swapped to a 10F FF bag. Since swapping over to the bag, I think I’ve been more warm, and I’m less worried about drafts, but the condensation issue is still there. I was hoping the bivy would move the condensation to the outer layer of the sleep system. But maybe there’s no solution.

    Would a bigger Mid help? Or maybe I should invest in an inner for the khufu.


    , I ended up switching to a xtherm, and it seems plenty warm for what I need it for. Took you guys’ recommendations from the thread :)

    Bryan Bihlmaier
    BPL Member


    Locale: Wasatch Mountains

    My experience with all bivy sacks I’ve tried, including ones from WPB fabric, is that all your condensation issues will just be moved to INSIDE the bivy sack – exactly where you don’t want it to be. I’ve never used one that did not soak my sleeping bag. I’ve never tried one with just a mesh top layer, but that wouldn’t add much warmth.

    Nathan H
    BPL Member


    @bryan – that sounds terrible. thanks for letting me know

    Eric Blumensaadt
    BPL Member


    Locale: Mojave Desert

    Winter sleeping hints:

    1. place outer clothes like pants under your mattress(es) for more warmth
    2. zip up your parka or GTX shell, cinch the hood and put fully over your the foot of your sleeping bag (makes the bag foot warmer and keeps tent frost from melting into your bag.
    3. wear a light fleece balaclava
    4. wear light knit glove liners (I know, sounds stupid – until you try it.)
    5. ** put boot liners into the foot of your sleeping bag for warm feet in the morning & telescope outer boot tops together to keep out spindrift snow. You only have to have painfully cold toes once to take this advice seriously. Don’t ask..

    If you do buy down pants be sure the down is DWR treated and it helps if they have at least half length leg zips.

    Bryan Bihlmaier
    BPL Member


    Locale: Wasatch Mountains

    @danepacker – Sage advice, assuming you’re using double boots. I had thought about mentioning the hard shell jacket over the foot of your sleeping bag but forgot. I also put whatever insulating clothes I’m going to put on in the morning, in the sleeping bag with me. It’s just a tiny bit easier to motivate myself to get out of my bag while it’s still dark if I know I don’t have to put on cold clothes.

    Ryan Jordan


    Locale: Central Rockies

    @n8fyn – my Decision Matrix.

    The question: “What’s the best way to spend weight to minimize condensation buildup in your sleeping bag?”

    Possible answers:

    1. more clothing insulation
    2. more sleeping bag insulation
    3. an outer quilt
    4. a water-resistant breathable bivy sack
    5. a waterproof-breathable bivy sack
    6. an inner tent

    1, 2 – more insulation inside the bag draws the condensation point further inward and will make it harder to dry the bag out; but is better for in-camp comfort and versatility;

    3 – places the dew point in the outer quilt, which can be thin and light and easier to dry out; or synthetic and less sensitive to loft loss due to moisture buildup;

    4 – increases the chance of condensation buildup on surface of bag which can wick into insulation; less airflow at surface of bag results in lower heat loss gradient and more condensation inside bag; good system when it’s windy and temperate;

    5 – similar to 4 but even worse in cold temps, but better when you need to keep precip off the surface of your bag ie, heavy rain under a tarp or sprindrift in the winter; ok if you expect high winds and/or precip and/or extreme frost inside tent in very very cold temps;

    6 – helps keep inside walls of tent drier where bag can contact them, minimizes accumulation of condensation on surface of bag; adds some warmth and draft protection to inside of tent.

    I generally recommend #3 for extended trips in subfreezing conditions where accumulation of condensation can reduce loft of a down bag over time.

    In very cold winter conditions I like a combo of #3 and #6.

    Under a tarp in the winter I prefer #3 and #4 or #3 and #5.

    I never combine #4/#5 with #6.

    I’m always a big fan of #1 because it adds versatility, comfort, and safety in camp.

    I wouldn’t spend money on the masterclass to answer this question alone – this one is really meant to provide a more holistic view of lightweight backpacking in inclement conditions.

    The next class I’m teaching is specifically about winter conditions and I’ll address this topic in a lot more detail, including how and when VB fits into all of this.

    Ken Larson
    BPL Member


    Locale: Western Michigan

    How about a waterproof VBL inside your bag?

    Our family used VBL’s in our North Face bags when we did a multi day XC ski trip across Michigan from Kalkaska to Empire and had no issues with condensation with our bags. The temp was in the 20* – 10* F range ( one of our camps in the evening the sap in the conifer trees were “cracking” …a first for all of us. ) that was optimal for the use of VBL’s.

    Skurka has a article he wrote in 2011 that might interest the cold weather traveling individuals.

    Eric Blumensaadt
    BPL Member


    Locale: Mojave Desert

    I agree about a synthetic “topper” quilt for your sleeping bag. It adds warmth and, importantly, holds most of the condensed moisture from your body.

    I happen to have a Thermarest synthetic quilt that attaches to a sheet which covers a Thermarest Trail Pro mattress but I’ve added 3 one inch wide elastic strips to go under my winter mattress and hold it on my down bag. I estimate it adds about another 10 F. to the bag. Along with a heavy base layer and puffy pants and jacket it can take my 20 F. down bag to around 5 F. The topper does dry fairly fast in the morning and is ready to pack after breakfast and breaking camp.


    Nathan H
    BPL Member


    thanks for the tips and suggestions, everyone.

    I decided to go with a feather friends 10F bag and a larger mid so my feet wont brush against the walls anymore.

    I also tried the synthetic top quilt option and I think that worked better in terms of temperature, but it was a bit too fiddly for me vs just a sleep bag. I may go back to that option in the future if I want to do 3+ night trips in the winter.


    Tipi Walter
    BPL Member


    If you want to really sleep warm inside a down bag—get an Exped Downmat of whatever configuration.  It comes in at 8R and you’ll feel a tremendous amount of heat radiating back up to you from below.  Have to try it to believe it.

    BUT it’s not the perfect sleeping pad—inflation is cumbersome (in my opinion) and there’s always a tendency one of the baffle seam-welds can blow apart.

    Bryan Bihlmaier
    BPL Member


    Locale: Wasatch Mountains

    @n8fyn Very good choice! If you’re going to buy another bag for winter, that’s a great option. I spent way too much (for how often I’ve used it) on a -10F WM bag with Gore WindStopper shell to protect the down from moisture on my winter trips. But I’m thinking of trying a light synthetic quilt over my “10F” down quilt (more like 30F to me). I am worried about it being fiddly like you discovered – especially since both will be EE bags that attach to straps wrapped around my pad.
    I’m thinking of sewing my own 2-quilt straps so that one strap set can attach to two quilts at the same time. Too bad EE doesn’t just offer that.
    BTW, in winter I use two quilt straps that each attach to my pad (wrap around it), rather than EE’s standard strap set with one that attaches and one that just cinches the bag. It helps keep drafts out if I roll over.

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