Winter Ground Insulation

[C-Stepper]

I went winter hiking Dec/Jan last year and nearly froze. After the 3 night hellacious experience was over, I zoomed down to REI and bought a BA Insulated Air Core. I didn't get to try it out until Feb, and then only for one night. It was a cushy dream, and I stayed toasty warm.

Two weeks ago, I'm dragging my gear out of the gear closet for an upcoming winter hike, and found that my BA Insulated Air Core had come apart on the inside. The insulation came unglued and strips of Primaloft were floating around inside the pad. In some cases one end was barely attached to the pad, and in other case the insulation had come completely off the interior walls.

Now, this pad was stored unstuffed in a closet with doors in an air conditioned, heated house, temp range 72-80F, nowhere near windows, etc...can't get much better than that unless you control humidity ;)

Anyway, of course, I returned the pad to REI, no paper receipt. They looked up the purchase electronically, and took it back and refunded my money, as I'm reluctant to get another BA pad so I didn't want another.

FINALLY, here's my question for the experts...Is a combination of a Thermarest Prolite 3 (self-inflater) and a Ridgerest (foam) pad enough for winter (likely no snow, but could be cold at 5000 feet elevation)???

...or should I be more serious about replacing my BA Insulated? I know combining the two pads may not be as cushy, and may be a bit heavier, but there don't seem to be many other choices.

[JimSproul]

Hi -

If you look in the most recent version of Fletcher's Complete Walker (IV?) you will find a very good discussion of ground insulation for winter camping. A number of good and inexpensive options.

Personally I go to a full length Thermarest in cold conditions. I like the Pro-3 but the Pro-4 is a bit thicker. I use a bivy sack year round (an REI Minimalist). In the winter I add half of a "Sports Blanket", you know that aluminized plastic sheet that has been around for years and years (about $15 at Campmor or REI). This combo works good for me. I have used it in near zero conditions but not on a snow pack, again see the Complete Wlaker for melting issues.

I investigated this issue after a very cold, early summer trip to the Rockies a few years ago when I was using a 3/4 Thermarest, it rained and sleeted for a week and my feet got COLD at night.

By the way, I use a tarp for most trips but shift over to a 4-season tent in winter. I use a Kelty Quartz-1, heavy by summer standards (about 5 pounds) but roomy enough for long winter nights and a vestibule big enought to cook in or keep the snow and muck out.

Enjoy

[bulldog49]

FINALLY, here's my question for the experts...Is a combination of a Thermarest Prolite 3 (self-inflater) and a Ridgerest (foam) pad enough for winter (likely no snow, but could be cold at 5000 feet elevation)???

...or should I be more serious about replacing my BA Insulated? I know combining the two pads may not be as cushy, and may be a bit heavier, but there don't seem to be many other choices.


I've used the combination Thermarest lite and Ridgerest on many cold winter nights and it works great. Using this combination in a tent pitched on snow I feel like I'm home in bed, very comfy.

[chris]

As another alternative, Exped makes a down insulated mat that a friend of mine has been using for a couple of years now with good results. I'm thinking of buying one for this winter. See http://www.mec.ca and look for sleeping pads.

[Alligator]

I have used in the past a Thermarest Ultralite (full size) and a generic blue foam pad and never had cold issues at temperatures above 0 and generally in tent. I have a prolite 4 now, and have used this in the 20's without a pad, no problems.

[Auntie Mame]

First, I love this site, as its such good reading for when I can't be outside.
For other-than-thruhiking-situations, one of the things we do to get out in the winter is to use snowshoes and pull skinny toboggans. We got onto this through Garett and Alexandra Conover who do traditional summer and winter guiding. We now have owner-built sleds and a most comfortable rig for camping that includes wall tent and folding titanium woodtove. Weight is less of an issue with sleds, but it does alter one's path and lead to river walking more than mountains. With the long nights, indoor cooking and lounging are enjoyed rather than endured, due to heat and candle-light, as well as some five-star cuisine! Gets the body moving and heart-rate up, lets ya see the sights and enjoy a slightly different way of walking in the woods.

Since the stove cuts out in the middle of the night, we use that combo of thermarest with closed-cell on top of a tarp, directly on a snow platform in the tent. Under 25 degrees or so, its dry and warm. Gets a little boggy up around 30 and above, but totally doable.

Good resource for this, Northwoods Ways.

[The Solemates]

the only thing i used on my thru was a Z-Rest and we had plenty of snow, with temps at 0F many nights. it provided plenty of insulation. i just dont see why people think they need a thermarest self-inflating pad and a foam pad for winter.

[Panzer1]

For winter and on snow, I use a 2" thick full length thermorest mattress. In the morning when I take my tent down the snow is never melted under where I slept. It might be a little compacted but not melted. That is evidence that the mattress has kept the heat from your body from reaching the snow below.

Panzer

[C-Stepper]

i just dont see why people think they need a thermarest self-inflating pad and a foam pad for winter.

You're only 24 years old...hopefully not, but someday you may understand.:cool:

Thanks, all...I'm going to carry what I already have, the Prolite 3 with the Ridgerest sounds like it will be fine. If I get cold, I'll come back here, post, and fuss at you :) .

[The Solemates]

You're only 24 years old...hopefully not, but someday you may understand.:cool:

Thanks, all...I'm going to carry what I already have, the Prolite 3 with the Ridgerest sounds like it will be fine. If I get cold, I'll come back here, post, and fuss at you :) .

if you say so...but i have hiked with older populations in winter conditions who do not use two either....

[C-Stepper]

if you say so...but i have hiked with older populations in winter conditions who do not use two either....

Yeppers, a thin woman whose had 2 kids, and a side sleeper to boot, I would never go without my inflatable pad...must have cushion. As for having only 5/8" insulation between me and snow...uh uh, Solemate, you're crazy. :datz

By the way, you may not have noticed, but I'm not going on an AT hike, and I'm not staying in an AT shelter on my trip...hopefully that's where the misunderstanding lies.

Anyone who sleeps on snow in the winter in air temps with the possibility of approaching zero (not in an AT shelter, etc.) with only 5/8" of sleeping pad under them is has my sympathy. I'm not out there trying to be a "tough guy", I'm trying to enjoy myself, which in this case means "stay warm", thus the reason for my request for suggestions from those who know.

You do it first, then I'll try it...naw, I take it back, I'm not interested. I'll take my extra layer of insulation for the 14 hours I'll be on the ground, in the snow, in winter, below freezing, in my tent.

[C-Stepper]

Hi -

Personally I go to a full length Thermarest in cold conditions. I like the Pro-3 but the Pro-4 is a bit thicker. I use a bivy sack year round (an REI Minimalist). In the winter I add half of a "Sports Blanket", you know that aluminized plastic sheet that has been around for years and years (about $15 at Campmor or REI). This combo works good for me. I have used it in near zero conditions but not on a snow pack, again see the Complete Wlaker for melting issues.



Hmmm...I hadn't thought of using a bivy! I can see where it keeps you warmer (smaller space), but doesn't the cold still seep in from the bottom? Sounds like I'd still have to carry the insulation layer, right?

[Youngblood]

The#Is10,

There are a couple of ways that I'm aware of for approaching ground insulation in cold temperatures. Down Air Mats, made by Stephenson and recently Exped, are probably the warmest, most comfortable and lightest weight solution. They are a pain to inflate. The insulated air mat you were using is similar but also very different. They apparently only put partial insulation in the top and that leaves a big air chamber on the bottom which is something you have to be careful with because it will severely limit how much additional warmth you get when you place additional insulation underneath it. With DAMs you have to use an inflation bag and they are a bit of a PIA to use. But you mess with them for 3 to 10 minutes and then lay on them for 14 hours (in the winter) so that is a tradeoff you have to call. There is also a cost issue.

The other way is to use the familar closed cell foam pads and self inflating pads. I'm trying to attach part of an article I was working on for one of Ed Speer's Hammock Camping newsletters where I give my pitch on how I think this works... I'll start with the disclaimer:

Disclaimer: This discussion should be taken as a rough guideline and only used as a starting point. Why? Because a lot of this is guesstimates based on personal experiences and your own personable metabolism is responsible in a large part for how comfortable you will be at any given temperature. Also there are many intangibles that sometimes play a part... humidity, how tired you are and the number of hours since you ate any food are just a few of these. With a disclaimer like this, one would question as to why say anything at all. That is a good point. My feeling is that most people need something to start with, a point of reference. In that regard, I hope this helps fill that void.

Bottom Side Insulation


Okay, what do I need beneath me when I am sleeping on the ground?

Often the ground is not at the same temperature as the outside air and to further complicate things sometimes the ground acts like insulation while at other times the ground acts like a heat sink. The extremes in how the ground acts are best understood by looking at the contrast between soft forest duff and solid frozen ground, a virtual block of ice. Obviously whether the ground is dry or soaking wet can also be a factor. All these things make specific ratings questionable... and that is before one factors in differences between individuals. Nevertheless, let’s proceed.


A Therm-a-rest® is a Therm-a-rest®, NOT!

Probably the most popular sleeping mats are the Therm-a-rest® brand of self inflating open cell foam mattresses. One of the more popular models is the ProLite 4. It is one of the Therm-a-rests® that uses their die-cut foam to make it lighter and pack smaller, so it isn't really designed to get all the insulating capability that one could get from a 1.5" open cell foam mattress. It is designed such that weight and pack size are more important than cold weather performance.

R-value is how Therm-a-rest® mats are specified in terms of insulating capability. Here is what I think Therm-a-rest® currently produces or has produced in recent years in their self inflating line of backpacking pads (the R-value numbers are likely for fully inflated mats):

1.0" ProLite 3 .......R-value = 2.3 (die cut foam)
1.5" ProLite 4 .......R-value = 3.2 (die cut foam)
1.25" Trail ...........R-value = 4.2 (solid foam)
1.75" Expedition ......R-value = 4.4 (die cut foam)
1.75" Basecamp ........R-value = 5.8 (solid foam)
2.0" Luxury Camp .....R-value = 6.1 (solid foam)
1.0" UltraLite .......R-value = 2.6 (die cut foam)
1.5" GuideLite .......R-value = 3.8 (die cut foam)
2.0" LE ..............R-value = 4.1 (cored foam)
1.5" Explorer ........R-value = 4.7 (solid foam)
1.75" Standard ........R-value = 5.8 (solid foam)

I don't know how Therm-a-rest® expects you to make use of these R-value numbers, other than a higher R-value means a higher insulating value. Insulation is not just about being warm or cold, there is toasty, warm, okay, cool, cold and freezing. I don't pretend to really know how to convert those R-values into temperatures that you will be happy with, but I can make a guess. I would propose a guesstimate using the following formula where the constant (k) is somewhere between 12 and 16.

Low Temp (degrees F) = 70 - k * R-value

Using this guesstimate, you would get something like this:

ProLite 3 ......42 to 33°F
ProLite 4 ......32 to 19°F
Trail ..........20 to 3°F
Expedition .....17 to 0°F
BaseCamp ....... 0 to -23°F
Luxury Camp ....-3 to -28°F
UltraLite ......39 to 28°F
GuideLite ......24 to 9°F
LE .............21 to 4°F
Explorer .......14 to -5°F
Standard ....... 0 to -23°F

Now these numbers are somewhat pulled out of the air to demonstrate what R-value should lead to. So what do you do if you are using a Therm-a-rest® that isn't warm enough? You can obtain a warmer one or you can augment what you have by placing a closed cell foam pad underneath it in cold conditions. For instance, if your ProLite 4 isn't warm enough, placing a RidgeRest closed cell foam pad underneath it with its R-value of 2.6 should augment your Prolite 4's R-value of 3.2, giving you an R-value of 5.8 (3.2 + 2.6 = 5.8), which is the same R-value as the BaseCamp and should offer about the same warmth, something good to somewhere in the vicinity of 0 to -23°F. At least that is the way it is suppose to work.


Closed Cell Foam Pads

Therm-a-rest® also produces closed cell foam pads that are unique in that they are not solid on the top and bottom surfaces, which provides more comfort with less weight. Their current models of this type are as follow:

3/4” Z-Lite .............R-value = 2.2
5/8” RidgeRest ..........R-value = 2.6
3/4” RidgeRest Deluxe ...R-value = 3.1

Applying the same equation yields the following table:

Z-Lite .............44 to 35°F
RidgeRest ..........39 to 28°F
RidgeRest Deluxe ...33 to 20°F

There are many other closed cell foam pads used for backpacking that are either solid or egg crated, etc. Most of these don’t have R-values specified and it makes it difficult to figure out their temperature ratings. Without any other information, I assign solid pads an R-value based on their thickness. This is obviously not always correct but is the best I know to do. The egg crated pads are perplexing because you don’t know for sure whether you can effectively trap air in the small crated parts of the pad. If you can their R-value would approach a value determined by their maximum thickness... if you can’t then the R-value would approach a value determined by their minimum thickness. The following table summarizes the values for generic closed cell foam pads:

1/4” ....R-value = 1.1 .... 57 to 52°F
3/8” ....R-value = 1.6 .... 51 to 44°F
1/2" ....R-value = 2.2 .... 44 to 35°F
5/8” ....R-value = 2.7 .... 38 to 27°F
3/4” ....R-value = 3.3 .... 30 to 17°F

[The Solemates]

Yeppers, a thin woman whose had 2 kids, and a side sleeper to boot, I would never go without my inflatable pad...must have cushion. As for having only 5/8" insulation between me and snow...uh uh, Solemate, you're crazy. :datz

By the way, you may not have noticed, but I'm not going on an AT hike, and I'm not staying in an AT shelter on my trip...hopefully that's where the misunderstanding lies.

Anyone who sleeps on snow in the winter in air temps with the possibility of approaching zero (not in an AT shelter, etc.) with only 5/8" of sleeping pad under them is has my sympathy. I'm not out there trying to be a "tough guy", I'm trying to enjoy myself, which in this case means "stay warm", thus the reason for my request for suggestions from those who know.

You do it first, then I'll try it...naw, I take it back, I'm not interested. I'll take my extra layer of insulation for the 14 hours I'll be on the ground, in the snow, in winter, below freezing, in my tent.

Im in no way trying to be a tough guy, I just know that the ZRest, in the past and on my thru-hike, provided plenty of insulation for me while camping in a tent, on the ground, in the snow, down to temps around 0F. My wife (who is 5'2" and 125lbs...so she obviously doesnt have the same body temperature regulation as me, at 6'4" 215lbs) used the same thing and didnt get cold either. It should be noted, however that we both used 0 degree bags.

I would also like to mention that sleeping in the shelters is much colder than sleeping on the ground. A tent adds significant warmth because the warm air you breath gets trapped and the tent protects you from the wind. In our case, with two people, a tent often adds 10 degrees of warmth over shelters. Sleeping in a shelter leaves you more exposed to drafts and the outside ambient temperature is colder.

Im not trying to tell you what to bring. Bring what you deem appropriate to have a good time. In fact, I have a full length ultralite thermarest as well that i often bring for cold weekend trips or car camping.

[Whistler]

That's so cool, Youngblood. It's a great starting reference.
-Mark

[The Old Fhart]

Youngblood, good informative post. What I do in the winter is take my Thermarest plus a foam pad. My reasoning is that the added insulation could be necessary for a good nights sleep and there is always a possibility, however slight, that the Thermarest could fail so I still have the foam that will at least get me through the night.

[Alligator]

Youngblood, good informative post. What I do in the winter is take my Thermarest plus a foam pad. My reasoning is that the added insulation could be necessary for a good nights sleep and there is always a possibility, however slight, that the Thermarest could fail so I still have the foam that will at least get me through the night.
Or after a rough passage through Mahoosuc Notch, you loose your Thermarest to the rock gods:o . But that won't happen too often.

[Chip]

I use a thermorest 72" X 24" X 3/4" thick pad year round. In the winter I add a 72" X 20" X 3/4" solid foam pad. This pad is made of Ethyleen Vinyl Acetaat , made in the Netherlands for NATO Troops. This pad only weighs 12oz. Whether in a 4 season tent or in an AT shelter I am always warm. I use a zero degree bag for the winter months. The mountains of WNC can have some rather cold nights with or without the wind chill. :)

[C-Stepper]

Youngblood,

Your article not only contains a wealth of information for one to use as a starting point, it reads clearly as well...good work.

Obviously, the focus of the article is R-value. I'm not a hammocker, but it makes sense that you aren't including insulated inflatables, as they have no place for the audience of the article.

Later, after your article has had some run time in the newsletter, and if you and/or whiteblaze is interested, would you consider adding an additional section to include insulated inflatables which would, therefore, make the article a little broader in scope (covering cool/cold weather ground insulation, and hammockers, too) and posting to whiteblaze?

Or, the article as is, would stand by itself, and would still cover a lot of folks...it would leave some holes, though, for those that don't hammock or the many of us that use inflatables/self-inflators.

This is great info for a winter hiker!