Extending sleeping bag ratings

bivy will give you wind protection and also add an air space that gives you 5 or 10F additional

there's a thread about layering where most people argue wearing clothes adds insulation

I think it's additive – if you wear 1 inch of loft of some insulation it will double the warmth of a sleeping bag with the same insulation, except you probably get a little compression.

If you have 2 inches of total loft it would probably be good down to 25F, although Richard N. has published some data that shows inches of loft isn't real accurate

– clothing inside or on top of the bag will extend yr rating … just watch out how you do it if in damp conditions
– vbl
– overbag/quilt
– hawt nalgene
– warm partner, preferably not a fuzzy bear

etc …

Yeah, I hear that. Over the past 20 years or so I have tried all sorts of things. Most work to some degree. Some work well for one night, etc…

Generally, I use two bags: A 0F winter bag and a 40F summer bag. Both are good down so they are about equivalent, give or take.

1) Make sure your bag is clean. A clean bag will loft a bit higher and perform better. Old down is fine, it breaks down but very, very slowly. It takes longer to break down than the shell, generally speaking. Water does almost all the washing a bag needs; a small, like 1/2-1/3 as much down soap as is recommended twice per year is good.
2) Hang it, don't keep it in a sack. Let the feathers breath.
3) Wear a down jacket/vest and long johns. This will add 20F-30F to the bag's rating in conjuction with a down jacket(dual use.)
4) Use a good warm pad. Or two if you have them. A lot of heat is lost below you. Nor do you want melted snow below you, wet snow is cold.
5) Stay dry. As Eric mentioned, if you use a vapour barrier, make sure it is as close as possible to you, not over the bag.
6) LIGHTLY drape your cloths over your bag. More than one layer may not pay, though. The loss of insulating value due to compressing the loft may hurt you as quickly as you add it. Good down is not very supportive.

In conjuction with the other stuff already said here, you can extend a bag about 30F, after that, you need a different bag.

If your target is 25 degrees, I would get a 30 degree bag + down layers that you would bring anyway.

On a recent weekend trip, I was very comfortable down to 27 in a true 30 degree bag + Montbell UL Parka + down hat + thinlight 3/8 inch pad over my Neoair short. The extra pad insulation is critical to extending a bag.

If you want to go any lower than 20-25F, get a 20 degree bag.

A hot water bottle in the form of a platy I am carrying anyway, in enough foam cooking cosy, mitts and dry bag to stay warm all night, can weigh nothing and increases calories output in the bag. I havnt had it leak but if it did the dry bag shuld protect me

As James suggested, you might be well advised to start by giving your current bag a wash with good down soap/detergent. That can do wonders. But note: do not use laundry detergent!!!!!
Atsko make some good products – have a look at their web site.

Cheers

I followed the care instructions on the Western Mountaineering website (with much trepidation considering the cost of my Ultralite sleeping bag!). It took about 9 hours (including a couple of water-only runs to get all the detergent rinsed out of the washer first), but the bag came out loftier than when I first bought it!

I have found that if I drape my down sweater over my hips inside my sleeping bag it adds more warmth than if I wear it. It also adds warmth to wear my rain gear to bed.

I haven't found a bivy sack to feel appreciably warmer. I guess 5 degrees isn't enough for me to notice.

It would probably add more warmth if I took a bandana bath and changed my clothes before going to bed since sometimes having some sweaty spots makes me cold. But I get lazy about that. If I can strip down naked in the last rays of the sun, thus drying off in some warm sun, then throw on some long undies after I'm dry, that works really well. But then I have to carry long undies which I try to save weight by leaving home.

I've actually ordered a summer-weight quilt to try to wear as a blanket inside my 20-degree quilt. I'm going to test it on my next trip later this month, weather permitting.

Since this last spring I have been using a 16 oz quilt down into the mid 20's with great success. This has been combined with a ul7 synmat and the items that I normally carry with me.

I sleep in long silk weight undies and add clothing as needed. I have found that draping my vest over me is much warmer than wearing it and wearing rain/wind jacket and pants adds warmth while cutting down on drafts.

In addition, if temps are expected to be low I wear a down hood (Katabatic Windom 1.5oz), that adds considerable warmth in bed and camp. I find that I sleep warmer and more comfortably if I clean up and put on dry clothes but I understand the reluctance to carry the extra weight.

Making sure that you "fluff up" your bag before retiring helps as well as making sure it is dry. If I have to pack a damp bag I will pull it out at lunch or during stops to ensure a dry bag at night. 10 or 15 minutes in the wind and/or sun can do wonders.

Hi, I’d like to revisit this toping real quick:

I’m planning on buying a Western Mountaineering bag, temp rating about -2C/30F. This will work perfectly for summer and shoulder season in the alps. For winter I’m planning to augment it by wearing (or draping over me) a 900 down parka by Luke’s Ultralite, to get the temp rating down to about -10C/14F, together with my Thermarest Xtherm plus a thermamest Z-Lite (for sleeping directly on snow).

I generally also sleep with base layers, light or thermal (Cap4) based on the temp.

What do you think of this plan?

That might work. You forgot to mention your ground insulation, a bag/quilt alone is not enough. A good R6 or more pad will help a lot.

Between 2011 and last year, I used a 40F bag. I just use my down jacket (around 3/4″ loft,) a set of long johns, a NeoAir and a 3/4″ Nightlite pad over that. I took it down to ~20F several times. I was fine. I did put my rain jacket on after a 0300 pee break when it got a little colder than 20, I believe my watch said 18F. A small tent would have added another ~10F, I believe, but I had a tarp with me.

Thermarest Xtherm plus a thermamest Z-Lite (for sleeping directly on snow).

That would be the ground insulation.

The ground insulation sounds good, but only adding a down jacket to a 30* bag in 15* conditions sounds really cold.  It would get you through the night, but relying on that amount of down for an extended trip sounds pretty dangerous.  If you run into an unexpected cold snap or your bag gets damp due to condensation, you might be in trouble.

Then again, Skurka, metabolism, YMMV, etc. etc.

Insulation for the legs is not often mentioned but is a key factor in extending quilt temperature rating. A down parka and down pants together can boost the rating by 15-20°F. I like Montbell Down TEC pants because they have full side zips.. Add down booties if feet are regularly cold.

If this is going to be the modus operandus going forward, it is also a good idea to get a quilt in a wider width to accommodate the down parka/pants.

Sorry, missed that…

I have tried it a lot with varying degrees of success, you have to make sure the parka and booties  overlaps the pants to seal in heat.  These days I prefer an appropiately rated bag and add a quilt if needs be.

Thanks Gentlemen, I have decided to go with a lower temp rated bag by Western Mountaineering after all. Those 200g should be well worth it!

The Alpinlite should do the trick!

The Alpinelight is a great bag, you will love it.

Phillip,

If you are interested, some sites offer free overfill of down.  I bought mine at Hermits Hut and got free overfill, which has helped on a few colder nights.

Glad you went with a warmer bag as that sounded like a recipe for a miserable trip!

For winter camping I bring along a inner bag liner from Sea to Summit. Not the lightest thing in the world but it adds about 10-15 degrees f and 8oz/225g. With my 30f quilt I’m good to the high teens. There’s a 25 degree f/15c option too but at 400g, I might as well just bring my second quilt as it’s only slightly heavier!

I use a Gossamer Gear 1/8″ pad under my Exped Synmat UL7.  That,  combined with dry socks and a base layer, help add warmth.  I sometimes add a wool beanie and/or a down sweater to further enhance my bag’s warmth.  My 25 degree WM Sycamore keeps me warm at least down to 20 degrees using all of the above.