Lightest two-pad (safety) setup for winter (R-Value ~5)?

I’ll post what I would grab from my stock if I was using a sleeping bag.  Someone can probably beat it for R-value/weight:
Therm-a-rest NeoAir XLite, regular, 12 ounces, 72″ x 20″ x 2.5″, R-value: 3.2,  packed volume 107 cu in.

Therm-a-Rest Z Lite Sol, regular, 14 ounces, 72″ x 20″ x 0.75″, R-vlue: 2.6, packed volume 550 cu in.

For a combined R-value over 6 (no, I didn’t add wrong, but I’ve factored in the air film in between them).

If I was bringing a quilt (which I find is fine in summer on a regular width pad), I might step up to the Therm-a-rest NeoAir XLite, long, 16 ounces, 77″ x 25″ x 2.5″, R 3.2, mostly for its additional width.

Though I’d be tempted to forego the Z Lite and just bring a slightly warmer bag.  Less redundancy, but much less bulk and I find I’m always fighting volume limits on winter trips.

Hi David,

Thanks a lot for the suggestion. Regarding a warmer bag without Z-Lite, this would again mean that I have to rely on an inflatable pad only. Which, seemed to me, can be a problem depending on where you are.

The lightest way I know to substantially guard the bottom of an inflatable pad is to use a 2 ounce 1/8″ thinlight pad from GG. The Thinlight combined with an X-Therm would do pretty well for overnight winter trips in moderate conditions. If you have a big tent or pyramid, then pack a second thinlight so you have room to spread out without touching the snow under you. If you have lots of sharp things (crampons, ice axes, ice screws) and camping at altitude, it’s hard to beat the bomb-proofness of a thicker Z-Lite pad instead of the thinlight.

I used to use an original NeoAir (and before that, a couple generations of T-rest) over a CC foam pad equivalent to a ridgerest. Now I use an Xtherm; I find it warmer and more comfortable than the old combination. The R-value numbers would indicate they should be about the same warmth, but I used a 3/4 length Neo over a full length CCF, so that may be the difference in warmth.

Only once in many years of snow camping have I had a pad failure, and that was with an old T-rest that was just plain worn out and leaking through the fabric near the valve. My bad for bringing the thing on the trip without testing beforehand, given the age of the pad. Punctures on a winter trip are pretty unlikely since I always have to stomp a level space and smooth with shovel, at the very least, and thus have a nice smooth surface with no pointy stuff.

If I were mountaineering, and had crampons and other pointy bits laying around, I’d probably go all CCF just to be safe, and deal with the less comfort. But for ski tours I am pretty comfortable having no backup for my Xtherm. The only thing I miss about not having the CCFpad is not having it for lounge chair use during lunch.

I would take a long look at the Xtherm as others have said. The bottom of the pad is made with thicker material than the lighter Xlite. Bring a pad patch just in case, but I really think it would take a lot of abuse to puncture.

16oz for the regular size, or 20oz if you prefer the long/wide.

I’ve had very good luck with my xtherm. No leaks and it’s lightweight and warm. It’s not the most comfortable, but it’s acceptable.

I’ve used a Z-Lite with my Xtherm in the winter and it was honestly so warm that I ended up sleeping with my bag unzipped and half off me.

That sounds very good. I might go for the Xtherm and use either a Exped Doublemat Half or a Thinlight.. or a better groundsheet.

I would vote for the two pad method if you are doing any snow travel and or cooking in a snow kitchen. The closed cell foam is much warmer than the snow to sit or kneel on.

I have had issues getting cold on top of a NeoAir during some non snowy nights when I have not sealed my Duomid against the ground and there is very slight breeze blowing.  I attribute it to convective heat lose through the perimeter of the pad since I have my pad outside my bivy sack.  When this happens I put the ZRest on top of the NeoAir.

Thanks Bruce – just for clarification, which NeoAir are you referring to?

Christoph: I experienced in with both the original rectangular NeoAir and the NeoAir xTherm with an R value rating of 5.7.  I found the NeoAIr more comfortable but under certain conditions less warm than my old ProLite when combined with a closed cell foam with the NeoAir on top.  I snow camp in the California Sierra Nevada below tree level in a Duomid when I do not expect a storm. Usually the temperatures are above 10 degrees F and often 15 or 2o degrees.  I often allow some room around the floor to allow ventilation, and there is sometimes a slight ground breeze of 1 mph when the cold air starts moving down hill.  I sleep inside a bivy sack with the pads underneath me and outside the bivy sitting directly on the snow.

I could feel the heat leaving my body through the pad, and the circumferance of the NeoAir felt very cold to the touch. I also toss and turn a lot. So I think I was losing heat through radiation and convection from the 4 edges of the pad and the cold air would circulate underneath me (since the NeoAir is really an air mattress). I did not like to place the pads inside the bivy because they are so slippery against the silnylon floor of the bivy that I would often wake up with them on top of me.

Putting the closed cell foam on top of the NeoAir made things better. I also started using my mylar emergency blanket, wrapping the slack aound the edges of the of the NeoAir to add another layer of fabric between the edges and the cold air.  I also considered adding lines of sticky silicon material to the silnylon bivy, or getting a bivy with a cuben fiber bottom, so I could move the pads inside the bivy

I reported this a few years ago on BPL and think my experience is unique. But I noted in the reports from the Outdoor Retailer exhibition that Cascade Designs has added internal baffles to the NeoAirs so air cannot move around inside the pad.

Cheers.

Thanks for the summary Bruce! That’s very interesting to know

Women’s size thermarest xlite (3.9R, 11.6oz) +  GG 1/8 foam (2.2oz, R0.6)+ 1/2 thermorest foam seat (1.0 oz).

Good at 17 degrees with a 10F EE quilt in the wind with snow on the ground.

Points: The women’s pad is rated differently. The gg pad can easily be doubled under the torso if needed.  Great to reduce slip. The thermrest foam sit pad goes on top the bag and under your air pillow. Every one  puts the bag at the feet. I prefer the shoulder space designed into the air pad  under my shoulders and not being taken up by a pillow. Spend the extra oz on booties (more uses) instead of grabbing an xtherm that’s 19.5 oz.

Nm

I’ve done a good amount of snow camping with just an xtherm and I think the material is plenty durable directly on the snow. The only thing to look out for is when there is sharp edges from hardened/broken up snow. Easy to flatten those out or remove them from the sleeping area though. For a longer trip where it could take multiple days to get back to the car, you could bring a torso length xlite for 7 oz and have a lighter & more comfortable backup for you and your partner than just ccf.

My lightest 2-pad setup:

->REI FLASH Insulated mattress (3 season version) R-Value 3.2  Weight- 15 oz.

->RidgeRest CCF pad (beneath the FLASH) R-Value 2.6  Weight 14 oz.

TOTAL R-Value 5.8 Good enough for -40 F. though my LL BEAN -20 F. down bag would require I wear my puffy suit for that temperature.

I use an Xthrm and a really thin CCF pad like these 1/8″ thick ones below 0F regularly, and the system works well and stays warm when using a real mummy bag. (I use a Kodiak for these conditions but would rather have something like a 0F Alpinist with 1000FP down and 7d fabric!)

I can attest to sleeping OK at -27F with this system for six hours, but I then got up early and started moving. I wasn’t able to blame the pad on the short night’s sleep!

Having had an inflatable deflate on me a few times over the decades I would be arguing that any system that included an air mat in my R value calculations wasn’t a fail safe system. So if a value of 5 was needed for safety at a given temperature then the only safe way to do it is with solid pads and any boost in rating by adding an airmat was a bonus.

I assume when saying this that you are not making use of any natural materials such as spruce or fir  branches laid on top of the snow, just a vapour barrier under whatever mat/pad system you will be using

I’d go Xtherm with a 1/4″ CC Pad.

I like Evazote, and that’s what I use. The 1/4″ Evazote is 7oz’s, but winter is not a time to take chances, and a 1/4″ Evazote pad will do by itself in a pinch. Heck, I used to sleep out on open snow at temps well below zero with an old 3/8″ Ensolite pad. However, that’s not comfortable or warm enough anymore for this 57 year old body.

An idea that I’ve toyed with is to take a 1/4″ EVA CCF pad of medium to high density, and take some 1/2″ lower density EVA foam and strategically bond strips and/or shaped pieces of that to the top of the full, 1/4″ pad. Combine with a sleeping bag.

Basically it borrows some from the Klymit concept of loft pockets, but you don’t have to worry about punctures etc compromising the system. The downside is that it will be bulky.

I’ve also been toying with this idea: take two sheets of 10 mil AeroZero sheets. Bond some high density 1/4″ EVA foam cylindrical  pillar pieces to the top of one, and at the edges, bond the other AeroZero sheet to the one with the EVA foam, with the 1/4″ EVA foam inside and in between the two AeroZero sheets. For greater comfort, take some 1/2″ lower density EVA foam pieces and strategically bond them on the outer top for cushion.

This is where it gets tricky, create a valve where you can pull a partial vacuum at home using say a Foodsaver, manual vacuum pumps, etc  Vacuum insulation is by far the most efficient thermal insulation and even partial vacuum is pretty good.

I’ve never handled the AeroZero material before. It might not be suited to even a partial vacuum; it might not have enough stiffness and might have too much flexibility and elasticity.  Also, they say it’s porous, so it might need a coating to better seal it.  Then creating a good valve system could be tough (at least it would for me).

Either way, even if the material did allow a partial vacuum to be pulled and to maintain it and with a good valve system, you would still probably need to occasionally re-pull a vacuum (might be a good ideal to have vacuum pump in your car that could be powered by same and do it right before you start your hike).

If it did work well enough, theoretically, you could get a pretty high R rating for relatively little weight with such a set up. Still would be bulky though. But if you put it in a lightweight fabric sleeve (when rolled up), and put it on the outside of your pack, should be fine.

And most likely quite expensive!  (I imagine the AeroZero sheets are probably quite pricey). Does anyone know the prices of this material? I contacted the company once, and other than a brief initial reply, they never responded with prices.

Here’s a thought.

They can now incorporate Aerogel into polyester fibres, maybe they could do the same with CCF pads?

What is the coldest temperatures people have taken an xlite and ccf pad down to? Im going to experiment with this, seeing as I don’t own an xtherm but I have some ccf pads in different thicknesses. If a 1 to 1.5cm thick ccf pad has an r value of 1.5 or 2, plus the xlite with rating at 4.2, it seems like that should be sufficient for around -30C. Anyone have experience with that?

^ If anyone is currently messing around with this, I’d be curious to know whether you use your ccf on top or below your inflatable. Even with a big R-value inflatable, some of your body heat is getting soaked up by that airmass.

some of your body heat is getting soaked up by that airmass.
True – for about 2 minutes.
But empty air mats are great at conducting your body heat to the ground underneath. They are bad.

Cheers

My go to is a Multimat in Evazote cut down to a mummy shape, wide shoulders, skinny feet, but only a bit longer than torso length. And then a similar shaped but longer air pad. I figure if anything poky is gonna poke a hole in my air pad it is probably much more likely to do just that under the parts where the majority of my body weight is. The added shoulder width is purely for comfort of course and extra weight.

Then again if your in the deep cold and hoping to rely on the only a thin CCF on its own that is probably never going to work if the majority of your insulation is always in the air pad. A good patch kit setup is probably the most important to have.