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Layering Sleeping Bags?
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Tom Clark
(TomClark) - MLife

Locale: East Coast
Combination on 11/14/2007 04:09:29 MST Print View

I mentioned in a previous post lately that I used an old Siera Designs down summer bag (40F) inside a WM Alpinelite (wide version of their 20F down bag) combination during a 2F night. I'm 5'6" and ~160, so there is extra room inside my WM bag alone. I thought it was a great, versatile combination that was better than spending another $300-400 for a 0F bag.

While there might have been some compreession of the bags, the inner bag filled up all of the voids next to me and provided a really good bafle around my neck. When I'm cold, I want everything tucked in around me. I don't know how to do that more efficiently with just a single bag and typical tossing during the night. There is probably a more optimum inner bag for to use, but I already have this other one. I don't know if my combination is more weight efficient than a single 0F bag, but there are other things I could buy with that money I saved.

William Webber
(micwebbpl) - F
Think it all the way through! on 11/14/2007 10:20:37 MST Print View

Pluses and Minuses of Overbags and Other “Bag Warming” Alternatives

There are several ways to extend/reduce the temperature range of your “basic” or “core” sleeping system:

In Hot Weather:

Pull the hood off your head if you are using a mummy bag; unzip the bag partially; stick your feet out with designs that permit this; unzip the bag completely and use it as a quilt. OR just use a quilt which allows a lot of these variations on the fly (by wiggling around and shrugging). Skip a tent, use a bug net over your head (tents are notoriously hot and muggy in the summer). Use a tarp if rain is a possibility. Adjust the amount of clothing based on the temperature (take off clothing and sleep in base layer - to keep the bag clean). Once again a quilt is useful because you can go to sleep in your trail clothing (or switch to your alternate set, if your trail clothing needs to dry out. I like to have the stuff in my pockets and feel naked if – I am, well, naked or just in base layer.

In Cold Weather:

Add a tent. Nothing keeps a secondary envelope of warmer air around you like a tent.

Add a bivvy sack. The secondary envelope of warmer air isn’t as great as with a tent, but it’s better than just the sleeping bag.

Add vapor barrier layers. This is especially important if you are going to be in a tent or bivvy sack, since otherwise moisture will accumulate in your sleeping system and reduce its efficiency. Oware used to sell a very light, impermeable emergency bivvy sack that you could wear as an “inner bag liner.” I prefer using my “light” rain gear – Houdini jacket and pants (the original Dragonfly version is REALLY a vapor barrier, but the Houdini builds up a “comfort zone” around your skin while keeping your sleeping system relatively dry). Wear the vapor barrier right over your base layer, which means your clothing will be “inside out” with the jacket and rain pants closer to your skin, and extra clothing on top of them.

Add clothing. Before thinking about an over-bag, think about puffy jackets and puffy pants (I like the Patagonia Micropuff with hood.and their pants). You should be thinking survival – if it’s really nasty, you will probably never have enough layers and overbags to just lie around waiting for rescue, so you have to count on building up therms by moving (hiking out!) and figure out the minimum you need for the coldest, wettest projected or historical weather (or somewhere in that vicinity, depending on your taste for risk). Naturally Primaloft, Thermalite, Polaguard all all superior to down, which can wet out. (If you hike out in worst case scenario, the “light rain” gear goes OVER the puffy layers. There will be some wetting out but probably not enough to impair the insulating layers.)

If you are STILL pushing the limits on your basic bag, ONLY NOW should you think about an overbag. OVERBAGS ARE INHERENTLY INEFFICIENT. You are trading a single, high loft bag with only TWO layers of shell fabric for an EXTRA TWO LAYERS OF SHELL FABRIC, not to mention potential weight additions like zippers.

If you are not a believer in vapor barrier/slow down clothing layers (the ultralight “light rain” clothing), the extra fabric layers are somewhat helpful in preventing humidity soak through/rain soak through, but the only advantage of using two bags is to save money.

My personal preference for the overbag option is to combine a summer weight quilt (which I usually spec in Jardine’s “extra insulation” configuration and a little oversize, since I sleep cold) with an ultralight mummy bag like a Montbell or Western Mountaineering – something around 16-20 ounces. It’s important to spec the quilt oversize so you can tuck it under you (and during the summer it’s adequate for couples camping). It’s also critical to use a bivvy bag (like the Bibler Winter Bivvy, except it runs a little small) to make sure air doesn’t seem under the edges of the quilt, or else to wrap a tarp around you (which traps air, another reason why you need vapor barriers as your first defense). As an alternative, you can purchase elastic bands (an inch or so wide) and sew them into “hoops” to wrap around your quilt over mummy sack.

Finally, check the stats and reports. You need a MASSIVELY thick (relative to ultralight hiking standards) ground pad to keep from losing heat through the ground, and it needs to be long enough to cover your legs – now is not the time to let your legs dangle on cold ground off the pad, or to drape them over “just” your backpack.

Siegmund Beimfohr
(SigBeimfohr) - M
Re: Layering Sleeping Bags (Montbell) on 11/14/2007 11:53:01 MST Print View


I was hoping you'd weigh in with your thoughts since I know you are very familiar with and use the Montbell products. Although I've been looking at true quilts for stand-alone summer use and as an overbag to my #3 UL SS DH (MLD's new XP quilt looks very interesting), I do have a UL Alpine Burrow bag #7 coming that I will probably use for summer. I've been using the #3 this year, always fully unzipped as a quilt so far, but it's too warm and heavier than necessary.

Specifically on the Burrow bags, do you have any thoughts on the tiled Exceloft insulation of the #7 compared to down? You mentioned owning both a #3 and #7 but didn't say which model although it read like they are both down; I assume you put the 7 inside the 3. How does the Burrow bag compare for bulk (loft) with the equivalent temperature down bag? Interesting that you get 32F out of the #7 with a thermawrap layer (both top and bottom?). I always use light long underwear in my bag to keep the dirt off if nothing else; I would guess with both bags nested there wouldn't be room for anything else without compressing insulation.

I'm also puzzled as to why the SS Burrow #7 Long ($125) is so much cheaper than the UL Alpine Burrow #7 ($164); it would seem that the SS system would be more complicated (it also weighs considerable more).

Synthetic on the outside bag would seem to be the better combination for moisture control, but I'm sure that won't work with the two bags I'll have. Anyway, am interested in any thoughts and experience you have with the different Montbell versions: Down Hugger vs. Burrow, UL vs. regular, SS vs. Alpine, etc.

Thanks, Sig

Brett .
(Brett1234) - F

Locale: CA
Sig,Layering Sleeping Bags? on 11/19/2007 02:01:59 MST Print View

Sig, I just saw your post. Ill edit this post with answers tomorrow, sorry; really busy today!

James Rivet
(airjay1966) - F

Locale: Los Angeles, California
Winter Bags and Quilts--What's best? on 12/08/2007 12:03:35 MST Print View

I am planning on doing some winter hiking in the San Bernardino Forest, and I am curious to know what people feel is a safe/ light and warm winter bag or quilt for such conditions. I plan on watching the weather so I hope to keep the bag/quilt as dry as possible (Not backpacking in freezing rain and falling snow). Temps. will sometimes be around 15 degrees F. I sleep cold. Any suggestions.

Jake Calabrese
(trekmore) - F

Locale: Colorado
Tent + WM 35 bag on 12/09/2007 21:22:06 MST Print View

I am planning on a quick 1 night trip in AZ, Payson or Prescott I am thinking. We may be near water. The temps appear to be at 26 at night, but that is in town, so I could see it being in the teens.

My planned gear
- WM 35D mummy
- SD Lightning tent (mesh inner + full fly)
- full length closed cell foam pad (1/2 inch?)
- 3/4 inch Thermarest ultralite pad
- Fleece pants, tops + poly or silk under that

I am thinking I will probably still need something else on top... I have a fleece liner I could cover the bag with, or I could use a emergency blanket (the thick kind silver/orange). I could also put on my Precip rain gear as well... Any thoughts on this on?

Does this sound like it would be warm enough, I would be warmer then another time at 10F in AZ... I think some cover or "topper" on the bag makes sense...

- Jake

mark wucher
(otis24) - F
One Mummy inside a rectangle on 10/15/2010 13:32:07 MDT Print View

I've used a 0 Degree Down Marmot mummy bagged stuffed into a 20 Degree Down rectangle bag for temps down to -10F and I was plenty warm. The rectangle bag is big enough not to compress the mummy. The downside is the combined weight is close to 6 pounds with the extra stuff sac you have to carry.

Tim Heckel
(ThinAir) - M

Locale: 6237' - Manitou Springs
No contact on 10/15/2010 14:24:13 MDT Print View

I've done something similar to Mark, a rectangular bag over a mummy. One advantage to this setup is you can store water and other things you don't want to freeze inside the rectangular bag and they won't be in contact with you inside the mummy.

I did a little math:
My Western Mountaineering UL weighs 29 oz, of that 16 is down.
A MontBell Thermal Sheet weighs 14 oz, of that 4.5 is down.
So, the combined fill is 20.5 oz and the combined weight of both "shells" (nylon, cord, zippers, etc) is 22.5 oz. That's a lot of "shell". For comparison the shell of the WM UL is 13oz.

David Olsen

Locale: Steptoe Butte
Re: Think it all the way through! on 10/15/2010 17:09:43 MDT Print View

Did you think this all the way through?

"In Cold Weather:

Add a tent. Nothing keeps a secondary envelope of warmer air around you like a tent.

Except a second sleeping bag!

A 3 to 5 pound tent is not nearly as warm as a 3 to 5
lb sleeping bag.

josh wagner
(StainlessSteel) - F
theory on 10/15/2010 22:36:56 MDT Print View

personally i'd probably opt to get a quilt (like stormcrow's burrow) that can have the footbox totally undone, therefor allowing me to lay it on top of my primary sleeping bag. this would allow both pieces of insulation to loft to their max.