Why is my sleeping-bag soaked every morning??

[Fallesafe]

I've have a mystery I'm trying to solve right now... I recently bought a ten-degree sleeping bag (The Western Mountianeering Versalite). And I'm about halfway through the NH Whites, right now, on a flip-flop of the AT. The bag has been amazing so far (a huge improvement over the 30 degree quilt it replaced). But I'm noticing that, every morning, I wake up with the entire bag covered in small water droplets. The tent I'm using is the Zpacks Duplex. And it's well known for condensation issues (as a single-wall tent). Every morning I wake up with the inner walls of the tent covered in droplets as well. But I don't think that's the source of the problem since the floor of the tent isn't wet in the mornings. And neither is the gear I lay out on the floor for the next morning.

Is it possible my bag itself is creating condensation?? Could it be that I'm generating so much heat inside of the bag that condensation is forming from the cold air outside of it? What could be the cause of this moisture in the mornings? This is the second night in a row that this has happened to me after two damp (not non-rainy) days.

A small part of my sleeping bag is already completely flattened from this dampness. And I'd be in for a terrible night if I was pitching my tent again this evening... But luckily, I'm in town tonight. And the town has two great outdoor stores in it. Is this a gear issue? What do I need to do to stop this from happening? Thanks!

[peakbagger]

Not a sleeping bag issue. Your tent is raining on your sleeping bag. The tent is radiating heat to the sky at night and is cooler than the interior of the tent so moisture from perspiration and your breath is condensing on it. Its cold out so you will naturally close the doors and minimize outside ventilation. If you up the ventilation of the tent, the outside air is much drier. Luckily you have relatively warm (for mid October) conditions this week.

[Traffic Jam]

There’s an excellent article on Backpacking Light that addresses this issue. Sorry, it’s behind a paywall but is worth the membership fee. There are many factors that contribute to condensation and the article addresses this. Basically, you need to wipe the condensation from the walls during the night and ventilate, ventilate, ventilate. Also, they recommend having a DWR coated down bag.

https://backpackinglight.com/single_wall_shelters_condensation_factors_tips/

[No Match]

I had the same issue as yours. After being rained on from condesation virtually every night of wind and/or rain, I threw the towel in and went back to a double wall. I have the Lunar Solo and there is no way to defeat the condensation. Most every one on my High Sierra Trips or numerous AT nights had the same problem. There is a tremendous amount of Duplex tents all over the US and the complaints to go with them. I simply consider all single walls a failure after talking to hundreds of people due to my gear junkie weakness. Manufacturers of single wall tents are extremely high quality, but defeated by the moisture issue. I don't like wet gear, especially when it wasn't raining. Yes, it will weigh more, but it weighs more when your gear is wet. Pic your poison. Happy trails!

There’s an excellent article on Backpacking Light that addresses this issue. Sorry, it’s behind a paywall but is worth the membership fee. There are many factors that contribute to condensation and the article addresses this. Basically, you need to wipe the condensation from the walls during the night and ventilate, ventilate, ventilate. Also, they recommend having a DWR coated down bag.

https://backpackinglight.com/single_wall_shelters_condensation_factors_tips/

[Tipi Walter]

I had the same issue as yours. After being rained on from condesation virtually every night of wind and/or rain, I threw the towel in and went back to a double wall. I have the Lunar Solo and there is no way to defeat the condensation. Most every one on my High Sierra Trips or numerous AT nights had the same problem. There is a tremendous amount of Duplex tents all over the US and the complaints to go with them. I simply consider all single walls a failure after talking to hundreds of people due to my gear junkie weakness. Manufacturers of single wall tents are extremely high quality, but defeated by the moisture issue. I don't like wet gear, especially when it wasn't raining. Yes, it will weigh more, but it weighs more when your gear is wet. Pic your poison. Happy trails!

I couldn't agree with you more. One way to lessen the impact of such condensation is to open all doors and sleep in a colder tent. It's counter-intuitive but it works. And go the double wall route.

[4eyedbuzzard]

The temperature of the outer shell fabric of the sleeping bag (as is the case with the tent walls) is likely below the dew point of the air/water vapor mixture inside the tent. You can't change the temperature, so you have to lower the relative humidity = ventilate the tent better. Even so, if it is really humid out, it can be a tough battle sometimes. Make sure that you are not exhaling into the inside of the bag as well. There is also the issue, usually at much lower temperatures like those on big mountains and arctic treks, of water vapor from the human body condensing on the inside of the outer sleeping bag shell and typically freezing. This can happen (without the freezing part) to a lesser degree at above freezing temps, but ventilation typically prevents such problems.

[Traffic Jam]

The most comfortable I’ve ever slept was under a tarp and in a bug net…no walls and total ventilation. If I weren’t afraid of heavy rain and my incompetence, that’s what I’d do all the time.

[Gambit McCrae]

The most comfortable I’ve ever slept was under a tarp and in a bug net…no walls and total ventilation. If I weren’t afraid of heavy rain and my incompetence, that’s what I’d do all the time.
Absolutely the same for me. My compromise is to use the SS2 with all doors open. It gives me the safety net of full protection when needed, but the feel of a tarp all the other times.

I too had the duplex and got rid of it due to its lack of needed length, and the condensation of a single wall tent.

If you have a 10 deg bag, and going sobo to HF you should be fine with leaving your duplex doors open on nice nights, and just zipping your bag up. I have the WM Antelope and do similar all winter.

Another tip is if you can handle the sensory of it on your face, wearing a buff over the nose will decrease the moisture you let into the air in your tent

[One Half]

I had the same issue as yours. After being rained on from condesation virtually every night of wind and/or rain, I threw the towel in and went back to a double wall. I have the Lunar Solo and there is no way to defeat the condensation. Most every one on my High Sierra Trips or numerous AT nights had the same problem. There is a tremendous amount of Duplex tents all over the US and the complaints to go with them. I simply consider all single walls a failure after talking to hundreds of people due to my gear junkie weakness. Manufacturers of single wall tents are extremely high quality, but defeated by the moisture issue. I don't like wet gear, especially when it wasn't raining. Yes, it will weigh more, but it weighs more when your gear is wet. Pic your poison. Happy trails!

Would using a tarp over the tent (in place of a rain fly) help with the condensation issue?

[BradMT]

You essentially breath a litre of water out into your tent at night. Single wall = condensation collection. I quit single wall tents over 10 years ago and have resisted the temptation to go back. No thanks.

[Tipi Walter]

You essentially breath a litre of water out into your tent at night. Single wall = condensation collection. I quit single wall tents over 10 years ago and have resisted the temptation to go back. No thanks.

One time I did an experiment and set up a Hilleberg double wall tent in the backyard and left it empty overnight. The next morning the inside of the fly was full of condensation water---no doors were open for ventilation btw. Point is, it doesn't require a human inside to produce condensation.

48660

[Fallesafe]

Ok, thank you all for your feedback.👍 I really did not want to hear that it was the tent, because I'm not excited about buying a new one... But if my options are to leave the vestibules open all night or wake up wet, I think I've gotta take the plunge.

[Odd Man Out]

The most comfortable I’ve ever slept was under a tarp and in a bug net…no walls and total ventilation. If I weren’t afraid of heavy rain and my incompetence, that’s what I’d do all the time.
On another forum (one from Sweden) I was following a discussion about the degree to which the tent's job is to keep you warm vs dry (in this case discussing solid vs mesh wall inner tents - In Sweden, "summer" hiking often involves cold, rain, snow, and wind). While a tarp overhead may keep you slightly warmer by blocking radiation cooling, the more ventilation you have, the closer the air temp inside the tent would be to outside, I would think. It would be interesting to measure how much warmer it is inside a tent with various option (tarp, single wall, solid inner, mesh inner, etc...), and if it might be possible to get the combination of warm and dry.

[OwenM]

What changed?
You went from a 30F quilt to a 10F bag...are you sweating in that bag(you may not even be aware of this, though), breathing into it?
When there's moisture inside your bag, your body heat pushes it away. If the temp reaches dewpoint inside your insulation, it gets trapped there. When dewpoint is reached outside your insulation, water vapor can condense into droplets on the outer surface.
If it were coming from the tent, it wouldn't be a new thing, so I'm just speculating a bit, and am not keen on blaming the shelter, which I see people doing for things I call "operator deficiencies" all the time
Regardless, better ventilation could help. Could you try pitching your shelter higher, and/or leave a downwind door open?
If so, those things, along with proper site selection, can go a long way toward mitigating "normal" condensation, too.

[Five Tango]

The most comfortable I’ve ever slept was under a tarp and in a bug net…no walls and total ventilation. If I weren’t afraid of heavy rain and my incompetence, that’s what I’d do all the time.

You might want to check out Evan's Backpacking on You Tube as he has the bug net/tarp shelter down to a fine science.He does not get wet,even in extreme conditions.Part of it is picking a spot with lots of natural forest duff and slope etc.

[Jonnycat]

Your tent is raining on your sleeping bag. The tent is radiating heat to the sky at night and is cooler than the interior of the tent so moisture from perspiration and your breath is condensing on it. Its cold out so you will naturally close the doors and minimize outside ventilation.

One of my bag nights this fall had me in an open meadow on a crystal clear night where the temps dipped down to 31F. As it turned out, there was no liquid on the the inside of the tarptent because it was ice.

When I got all of the gear out of the tent and went to fold it up I gave it a good shaking and ended up with a softball size snowball in the corner of the tent.

[Tipi Walter]

One of my bag nights this fall had me in an open meadow on a crystal clear night where the temps dipped down to 31F. As it turned out, there was no liquid on the the inside of the tarptent because it was ice.

When I got all of the gear out of the tent and went to fold it up I gave it a good shaking and ended up with a softball size snowball in the corner of the tent.

Even a double wall tent will get inner tent condensation when conditions are right and this stuff will freeze into ice crystals unless the tent is fully vented with both doors open etc. (Though the second inner tent displaces a large amount of inner fly water coming down onto gear vs a single wall).

In deep cold the trick is to pack up and move every day to dislodge this ice from the inner tent---and then on set up at the next camp you can shake the inner tent to dislodge all this ice and sweep it out. I've collected up to a full liter+ at times.

If you don't move every day in cold temps and instead pull zero basecamp days this ice doesn't get dislodged unless you take everything out of the tent and do a wipe down---and often morning ice will become falling water by afternoon. Not good.

48661
Cold tenting.

48662
Sweeping ice of tent on next day's camp arrival and set up.

[zelph]

One time I did an experiment and set up a Hilleberg double wall tent in the backyard and left it empty overnight. The next morning the inside of the fly was full of condensation water---no doors were open for ventilation btw. Point is, it doesn't require a human inside to produce condensation.

48660
Excellent experiment....thank you for sharing.

[Leo L.]

I'm having pretty much the same issue, depending on the weather conditions overnight everything inside the tent, and the tent itself is more or less soaked.
Leaving the tent fly open seems to help, but it comes down to a tradeoff between staying warm and get soaked, or staying more or less dry but keep shivering through the night.

My solution is, to shake and wipe everything down a bit in the morning and pack up all the wet stuff, and later when taking my breakfast in the morning sun I'd spread out the essentials to dry out.

[peakbagger]

Stephenson's Warm and Light (now Warmlite) https://www.warmlite.com/ has been around for 50 years and they approach this from a different tangent https://www.warmlite.com/vapor-barrier/. Their approach is vapor barrier gear. The concept is instead of waterproofing everything in the tent including the sleeping bag so that the insulation can not get wet. The military mickey mouse boots popular in cold climates work this way. Vapor Barrier gear is definitely controversial although it does have a place in extreme conditions. About the most I have used is vapor barrier socks that do keep winter boots far drier.

At one point I saw some discussion for folks in winter tents to wear respirator masks through a heat exchanger to the outdoors so that the moisture in the hiker breath would not collect in the tent.

[PatmanTN]

Fallesafe,

This is an interesting issue and I'll add this for what it's worth: I have a WM microfiber Lynx (rated to -10F) as my deep winter bag and I have the exact same issue no matter what shelter I use (typically double wall). The top of that bag is almost always wet in the morning. I can't explain it technically but I think its something to do with high-loft bags and that shell materiel. I always bring along a little towel to wipe it down in the mornings (my bag not the tent).

[Coffee]

Over almost a couple hundred nights in my Hexamid Twin over many years, condensation is just a fact of life in some settings, but very much avoidable in other settings. Particularly out west, I am usually able to avoid the worse of the condensation problem by good campsite selection and ventilation, which is helped by the dry air with very low humidity. In fact, the only times I have suffered from condensation in the West is when I have camped in or near meadows or very close to bodies of water. Camping under a tree canopy elevated from lakes or streams usually avoids the problem. Ventilation is also critical. Closing the vestibule is recipe for condensation.

On the AT, with the higher humidity of the eastern United States creates many more challenges. For the most part, I avoid backpacking in the east during the hottest and most humid summer months. By September in the mid-Atlantic, conditions are much less humid usually and less prone to condensation issues.

I own but have yet to use a zPacks Altaplex (it was intended for a thru hike out west that I had to cancel). In theory, the Altaplex should have less condensation issues because it looks like it is more open for air circulation. I may be selling the Altaplex, however, since I am definitely not going to be able to thru hike for a while and my Hexamid Twin is still OK for the few overnights I might be able to fit in for the foreseeable future.

Single wall vs double wall is obviously a weight issue. The Copper Spur UL 2, super popular tent, is almost three times the weight of a minimalist single wall shelter.

[MapleHiker]

I've gleaned much information from you over the years Tipi. You should write a book about your travels and all the emperical knoweldge you've acquired in doing so.

[wornoutboots]

I agree with opening up your tent in colder (all conditions) I sleep in a Copper Spur 2 & always have 1 door rolled open. I just returned from the Big South Fork where I slept 100 feet from the River in low 40's and woke to a dry tent, sure it was a little colder but that's why you bring a warm bag and an adequate pad.

[TwoSpirits]

Agreed. I try to always sleep with at least one vestibule of my tent as open as [precipitation] conditions allow. I have still had some frost build up inside, but definitely manageable.

When using my full-fabric inner tent in very cold and blowing snow forces me to keep the vestibule closed, I try to create a "draft" inside by cracking the door low on one side and high on the opposite side...the thinking being that the cold air will enter on the low side and push the warmer, moist air out the high side. I do still get frost, but I think it helps a little. ?

My biggest challenge moisture in/on my sleeping bag is dealing with how it is always wet (and icky!) right near my face, due to my warm breath on it all night. I avoid burying my head & face inside, and wear a buff over my mouth and nose, but still deal with that.

[George]

best way to avoid condensation: stop breathing

[Time Zone]

On the AT, with the higher humidity of the eastern United States creates many more challenges. For the most part, I avoid backpacking in the east during the hottest and most humid summer months. By September in the mid-Atlantic, conditions are much less humid usually and less prone to condensation issues.



Relative humidity can still soar overnight, even peg the needle, in the cooler months of the east. Part of that is the definition - cooler air holds less moisture, so it's easier to get higher RH readings. But still, even with a cool dry day, RH can spike overnight. It's almost always something to consider.

Synthetic bags won't collapse loft with moisture, but they can still get damp from condensation, and therefore should also be aired out to dry in the daytime.