Hello Mighty Adventurers!!

After spending 6 nights in my new Big Agnes sleeping bag in 30* and lower temps I have found that I love my bag... my top was always warm... no drafts... nice and comfy. However.... my bottom (or whatever was against the ground) was not so warm. The cold from the moist ground below me spent 6 nights seeping right through my sleeping pad and into my bones... so.. for those of you familiar with sleeping systems... I pose this question....

What type of sleeping pad is warmest? An open core, a closed core, or a foam (egg crate type)? The sleeping pad I have now is a Pacific Outdoor Ether Compact 6. It's what I would call an open core (you blow it up and it has several long, hollow, tubes filled with air). It seemed to me that the open tubes helped to bring the cold air closer to me instead of insulating me against it.

What do you all think?

You may want to take a look at this Thread

double up. Two foam pads layered are warm, or one foam on top of an inflatable, or get the cadillac of pads, an Exped Downmat (expensive).

In winter I use two RidgeRests, one full length, one 3/4 length. Warm enough for me on frozen ground, but then I have a sleeping bag that does have insulation on the bottom, unlike those Big Agnes bags (which I think is where your problem starts). 30 degree nights aren't anywhere close to the temps I would need a second foam pad.

Thanks guys...

Is there a difference between the open cell and closed cell type pads though and the way that they insulate?

Closed cell pads hold the air in tiny bubblelike structures thus there is no convection flow of heat through the pad.

A typical air mattress with the big tubes does have a lot of heat loss to the ground through convection. A closed cell pad like the Z-rest or Ridgerest will insulate pretty well and the blowup pad on top will give something like soft comfort. On really cold snow a second closed cell pad will help a lot especially under your tent or ground cloth.

Thanks Mike... thats exactly the answer I was looking for. I had assumed as much... but really wasn't sure. Now I know! (And knowing is half the battle, Yo Joe!)

You're welcome.

My last snowmobile-camping trip, I took a full-length closed cell pad and a short thermarest. The Thermarest it turned out, had a hole (#!@# cat!) and went flat in a few minutes. But the closed cell plus whatever the thermarest contained within was enough insulation. (We were camping inside a tent, but on snow.) I used my summer 2 lb down bag, but also used another as a blanket over the top. I was toasty.

Looks like it's time to start shopping for a closed cell pad...

Oh... one more thing about those closed cell pads: They're too doggone hard for me in most situations! I was surprised that I didn't suffer on that trip because of the thermarest failure.

Looks like I'll have to start part and parceling borrowed gear to see what works best for me before I go out and buy something....

Thanks everyone for all the input....

snow is usually the warmer ground surface in winter. 32F, not much colder, especially once you set up on it. Rocks and soil, if you find it in the cold season, can be a super cooled surface that will challenge a single foam pad.

On the other hand, snow has a much higher specific heat than earth or rock (and most other things), and even at higher temperature, will suck up heat much faster than even significantly colder rock. You can demonstrate this simply. Put an ice-cube size rock in the freezer overnight. Next day, hold the rock in one hand and an ice cube in the other for a while, or drop each in a glass of water and feel the difference.

Thats why we use ice in our drinks instead of, say, chilled marbles, and why melting snow is such a lousy (if necessary) source of water.

For thermal qualities, give me dry rock, gravel or sand over snow any time. Frozen soil is somewhere in between.

ice doesn't "suck the heat" from the glass, it melts faster because it is warmer than the rock, which will probably form ice on its outside when droppped into water. But none of that simulates sleeping on an insulated pad.

Holding an ice cube and a cold rock in thin neoprene gloves for half an hour is what you want to do after that night in the freezer, and do that in a place that is as cold as that freezer. Now you have a fair test that simulates what happens under your ground pad and tent floor when it's really cold.

The idea wasn't to simulate the sleeping pad, but to demonstrate that ice and snow absorb heat a lot faster than granite. Try the ice and rock experiment. You may be surprised. About 1 oz of each in 4 oz of water

But that aside, the test with the neoprene glove will demonstrate the same principle, regardless of the ambient temp. The ice cube will feel colder, sooner, than a much colder rock of equal mass. And the rock will warm up to a comfortable temp before the ice melts,

-- Mr Wizard

Which Big Agnes bag did you get? I've got a 6-year-old Storm King, which is supposedly rated to 0 degrees. Supposedly. I've got an equally old Big Agnes inflatible pad which has fibers of synthetic insulation inside. Pad Here It works great, but it really cold temps, I double up with a 3/4 length z-lite sleeping pad from my head to my knees, and then I put my backpack under my feet. Works like a charm. It was quite cold at Meysan Lake this past weekend, and I was directly on the snow. This combo kept my warmth from escaping down. I will say, although I like the extra room afforded by my Big Agnes, I think I should have got the model with the slimmer cut so there is less room for my feet to heat up. That's really the only spot I have trouble.

Bottom Line: a big heavy expensive pad just for winter use is not necessary. Use a 3 season pad coupled with a light short closed cell pad, and your pack. Good to go. That is, unless you like carrying tons of weight and spending lots of dough =)

Wait--you mean that's not what backpacking is about? Doh!

I am very interested in the results of this poll. I'm thinking of getting one of the Big Agnes bags and need to know when to switch from one of their 15 degree pads (recommended with the 15 degree bag) to carrying a thin closed cell foam layer to add insulation.

I currently use a 10"x10" square of closed cell foam pad cut from a old sleeping pad as my "butt pad" so I can sit in comfort while having lunch or on sit down breaks on day hikes for only a few ounces of weight. And it is such a bright yellow-green I can't leave it behind when I pack up!

By the way, I looked up the r-value of the Pacific Outdoor Ether Compact 6: it's r-value per the manufacturer is 2-3.

Big Agnes lists R-4.1 pads for 15 degrees temperatures, so adding your pad to a closed cell one will work.

Update:

Big Agnes came through for me. I've had my pad for over 6 years. I'll patched a few pinholes that were my fault, but recently the side seam came unglued in a couple small spots. I sent it back to Big Agnes for possible repair, they sent me a brand new replacement for free. Talk about good service, and I love the pad itself.