Breathability vs. Water Resistance in a "3" Season Sleeping Bag

[glademaster]

That sums up the question. I'm about the order myself a new sleeping bag for backpacking, and spring ski touring trips. I live in western Washington and will be doing a good bit of backpacking west of the Cascade crest and in the Olympics. Given those conditions, is a highly water resistant bag (i.e. Windstopper shell) worth the expense, weight, and impact on breathability? Or would something more breathable, with less water resistance like a microfiber shell make more sense? I will be transporting the bag in a dry sack, so moisture shouldn't be too problematic while it's packed, but I am curious about experiences with the two options from people who have spent a good bit of time in these mountains.

In Colorado or Utah the choice would be obvious, but here it seems like maximizing water resistance is important. That being said, I don't want to end up wetting the bag from the inside because my sweat condenses on the membrane of the shell fabric. This is not for true winter camping, but the bag will likely get used in shoulder seasons or traveling in the Rockies were nighttime lows in the 10-20 degree range are a possibility, however, most of the time it will be used in that delightful PNW weather of 35-45 degrees with 95% humidity.

[skiing-in-jackson]

IMHO water resistance always beats breathablity. I've had some rough nights out and they almost always involve getting wet from the outside.

Do you use a bivy sac? I don't roll without one. It also has the added benefit of keeping your tentmate's oatmeal/beer off your bag.

[GeezerSteve]

Go for it. I custom order my bags and quilt with (alleged) waterproof breatheable outer shell, e.g., eVent or Pertex Shield. WM offers Gore Windstopper, which is not quite as stormproof, but works fine inside a single wall shelter, under a tarp or most nights under the stars. I have used my WB outer shell bags hundreds of nights and persuaded it's the way to go for PNW mountains. (I like single wall shelters, sometimes sleeping under tarps and having the option of sleeping under the stars on a clear night.)

IMO, the bivi bag alternative is too heavy if you are also carrying a tent or 'mid shelter. An in-between option is the 8 oz. Montbell Breeze Dry-Tec sleeping bag cover DIY modded by sewing in a half zipper. (Stock no zipper sucks.) Sewing in #5 zipper adds a couple oz. I've done the mod for my wife and a few buds and they like it, although I personally prefer a WB outer shell.

[detrusor]

WM? WB?


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[John_B]

Western Mountaineering. Waterproof Breathable.

[trex_9]

Western mountaineering for sure. Check out their MF line. Its more beefed up in the areas you mentioned.

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[Name Redacted]

Western mountaineering for sure. Check out their MF line. Its more beefed up in the areas you mentioned.

I love WM as much as anyone, but in the Cascades it would seem like you'd want synthetic over down right?

[GeezerSteve]

I love WM as much as anyone, but in the Cascades it would seem like you'd want synthetic over down right?

We always use down bags in the Cascades and Olympics, taking great care to keep them dry. I haven't had a syn bag in 30+ years.

FF is every bit as good as WM and it's close to OP. If you're looking at a FF custom bag, talk to Todd at the FF store.

[riff]

I agree with GS. High quality down ftw.


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[Name Redacted]

Gotta day I knew that was coming. But synthetic could still be high on the OPs list for that reason.

[old goat]

I've had a WM bag since before WB was a thing for bags. Not in the NW, but I've used it on trips where it rained every day for a week and never found down and the lack of water repellancy to be a problem.

[glademaster]

We always use down bags in the Cascades and Olympics, taking great care to keep them dry. I haven't had a syn bag in 30+ years.

FF is every bit as good as WM and it's close to OP. If you're looking at a FF custom bag, talk to Todd at the FF store.

I was looking seriously at FF, but their lead time for a semi custom bag is pretty long at the moment. Not saying I've ruled them out, but I would like to have a bag before September.

I can't seem to find hydrostatic head numbers for Shield, but I've seen Windstopper cited at 12,000mm, which is pretty damn waterproof. That being said, I wish WM made a 15 degree GWS bag in a cut between the Apache and Badger, which leads me back to FF. I think a 5 degree bag would be overkill, but then WM Antelope is ideal dimensionally for me.

Synthetic might make more sense at face value, but if your sleeping bag is wet enough for a down one to be rendered useless, you're going to be miserable regardless of the fill. It also seems synthetic bags have a short lifespan.

The responses here are 180 degrees from what most of the research I've done indicated, but GS knows a thing or two about camping in the PNW, so I'm inclined to pursue a highly water resistant option (I say highly water resistant because even if the fabric is waterproof, it isn't seam taped).

[bodywhomper]

The synth filled bags should be a lot cheaper than the nice down bags.

If you have the bling, get the light, high loft down bag with the fancy repellent fabric. And be smart with your systems for keeping it dry in bad weather. Sometimes that could mean pulling the plug on a trip.

I'm sure there are plenty here that have 1st or 2nd hand experience with things gone wrong with down bags. 3 days tent bound in a late spring sierra storm, my tent partner's down WM bag was starting to get some balling, but we were having lots of interior drips due to snowload on a light 3 season tent. 2 friends were tent bound for almost a week attempting a winter ascent of Shasta. Full bag downbag wet-out madness/misery a few days in. Ive sat out a big CA winter storm on a coastal trip and awoken our last day soaked (but still warm) in a synth bag. A buddy weathered a summer storm in July on Rainer in a cave with soaked down bag. He lost most his toes. I remember working at marmot when this Scottish kid bought a -20*F synth bag because he did not want to go through "that" again. It was funny when he took a terraplane backpack of the shelf to see how much space the bag took up.

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[Name Redacted]

Synthetic might make more sense at face value, but if your sleeping bag is wet enough for a down one to be rendered useless, you're going to be miserable regardless of the fill. It also seems synthetic bags have a short lifespan.

The responses here are 180 degrees from what most of the research I've done indicated, but GS knows a thing or two about camping in the PNW, so I'm inclined to pursue a highly water resistant option (I say highly water resistant because even if the fabric is waterproof, it isn't seam taped).

We always use down bags in the Cascades and Olympics, taking great care to keep them dry. I haven't had a syn bag in 30+ years.

You just have to ask yourself, are you going to be a badass pro camper like GS? Are you willing to use a VB? Or are you more of a guy who wants to have a little more margin for error?

Definitely not saying that it can't be done, or that GS is wrong. He's got thousands of times more experience than any of us at camping in the PNW. But like I said, he's a pro at it. Are you?

And on lifespan. Synth will last a long time if you take care of it. Down won't last very long if you don't take care of it. Mileage is relevant, but you'll at least get a few seasons out of it, and by the time it wears out, you'll be wanting a new one anyway. Synth is easier to wash so your bag doesn't smell like farts and beer.

ETA: if you are worried about wetting out from the inside, you can use a VB inside your bag.

[CascadeLuke]

We always use down bags in the Cascades and Olympics, taking great care to keep them dry. I haven't had a syn bag in 30+ years.

FF is every bit as good as WM and it's close to OP. If you're looking at a FF custom bag, talk to Todd at the FF store.

Have been following this discussion as we are looking for bags too. Although don’t require fancy customs with our more rec style vs mountaineering aim.
Curious without arguing- if you haven’t used a syn bag in 30 years how do you know if they’re up to snuff or not? One thing that’s evident to me on outerwear is that syn has come pretty far in 30 years as well as WB materials.
What’s the advantage of down in direct comparison with same temp rating? Thanks

[GeezerSteve]

syn has come pretty far in 30 years

It has? We have state of the art syn garments and AFAICT synthetic insulation improvement has been incremental in the past few decades (notwithstanding marketing hype to the contrary). High quality synthetic insulation works fine when its new, but it starts losing loft with the first stuffing -- yeah, even the latest greatest syn. It will last longer if you roll it (instead of stuffing) then put it in a bag. That results in a larger stuffed bag, but maybe that's not a big issue because if compressibility is a high priority, down is the only choice.

FTR, I plan to make some synthetic sleeping quilts in the next few months while I'm recovering from TKA surgery.

ETA: I have not used hydrophobic down coating, e.g., Downtek

ETA2: Re lifespan: A high quality down bag is a lifetime purchase because it will not lose loft (measurably) with thousands of stuffing cycles.

[glademaster]

It has? We have state of the art syn garments and AFAICT synthetic insulation improvement has been incremental in the past few decades (notwithstanding marketing hype to the contrary). High quality synthetic insulation works fine when its new, but it starts losing loft with the first stuffing -- yeah, even the latest greatest syn. It will last longer if you roll it (instead of stuffing) then put it in a bag. That results in a larger stuffed bag, but maybe that's not a big issue because if compressibility is a high priority, down is the only choice.

FTR, I plan to make some synthetic sleeping quilts in the next few months while I'm recovering from TKA surgery.

ETA: I have not used hydrophobic down coating, e.g., Downtek

ETA2: Re lifespan: A high quality down bag is a lifetime purchase because it will not lose loft (measurably) with thousands of stuffing cycles.

Steve, do you use a VBL inside your bags in above freezing conditions? Have you encountered issues with shell material not breathing well enough for sweat to evaporate? I don't intend to dry clothing inside the bag while I sleep, but waking up in a clammy bag that I've dampened from the inside out is a concern of mine with Windstopper or Shield. It isn't that uncommon for me to sweat quite a bit at night, even if I am not feeling hot at the time. I suppose I tend to sweat quite a bit in general, which I suppose could be an argument for a VBL or a more breathable bag.

Most of my sleeping will be done in a lightweight double wall tent (basically bug netting with a rain fly), with some open air camping when the weather or location is highly conducive to it. Condensation in the tent seemed to be a bigger issue in drier climates than it has here so far, which seems counter-intuitive.

[GeezerSteve]

Steve, do you use a VBL inside your bags in above freezing conditions?

No

Have you encountered issues with shell material not breathing well enough for sweat to evaporate?

No, not for years, because I properly ventilate, one reason I prefer a lightweight down sleeping quilt for 3-season use which IME is the best way to avoid night sweats >20F. If a mummy bag is all you got, unzip it and use it as a quilt.

It isn't that uncommon for me to sweat quite a bit at night, even if I am not feeling hot at the time.

If that's the problem, synthetic is not the answer. Synthetic insulation breathes like shit, far less so than down with ePTFE outer shell. Syn claminess is the biggest reason I abandoned syn bags. If you're sweating inside a down sleeping bag, you're doing something wrong. (OTOH, sweating inside a synthetic bag is often unavoidable.) Have you considered a sleeping quilt?

Condensation in the tent seemed to be a bigger issue in drier climates than it has here so far, which seems counter-intuitive.

Give it time. Condensation/dew point inside tent has several variables, e.g., elevation, proximity to water, ambient humidity, tent venting. No doubt that morning condensation is often bad at high elevation on clear nights, although IME it's not as bad as camping near a subalpine lake in fog and no wind.

If syn works for you, go for it. For me and all my fellow mountain travelers, we'd rather deal with keeping down bags dry (quite easy, actually) than to deal with the disadvanages of syn, i.e., bulk, clamminess, gradual loss of loft, the need to buy a new bag every few years and to carry a bigger/heavier pack to carry the bulkier bag. It's an easy choice for me and my buds.

[bfly]

Ugh! I had a Marmot Gore-tex bag years ago. It was like sleeping in Ziploc bag. What a miserable sleeping bag. I used a Windstopper fabric bag from Mountain Hardwear for years after that and it was marginally better. I found that waterproof(ish) fabric just traps body moisture in the bag and eventually wets out the down from the inside.

I now have a couple hydrophobic down quilts that work pretty well.

[Norseman]

With your planned use, I'd suggest that the full on Pertex Shield or equivalent burly face fabric is overkill.

I use a FF Swallow UL 20 (Pertex Endurance 10-denier water-resistant breathable) and it's been The Shit for general 3-season PNW use with traditional 2-wall tents plus the occasional bivy.

I don't have relevant experience to comment on the tougher expedition-oriented fabrics, nor do I often commit to huge through-hikes or week-long alpine outings with good odds of getting weather-fucked like Steve does 😁.

I've slept out a few times in it with heavy dew and frost, and the shell beads up nicely. Never felt damp inside. Never had a breathability issue, but I sleep cold and generally don't sweat much unless my wife is in the mix and will ventilate for heat dump.

Their newer 20-denier YF (Pertex Quantum) fabric looks nice, too... a little more waterproof, a little heavier (50g/bag).

Custom bag probably not necessary with your build...?

My next bag will be a quilt.

[glademaster]

Quilts seem like a huge pain in the ass to me, but I haven't tried one. I'm not opposed to the idea, but I don't feel like having to put together a whole new system, or learn new techniques for staying comfortable while camping. I've also learned that unless it is truly cold, I don't sleep very well wearing a hat, so having a hood and draft collar is important to me.

I think I'm going with the Microfiber shelled bag instead of the full on WP. This is a spring/summer/early fall bag, so it isn't a piece of expedition equipment that needs to keep me warm if I get stuck in a storm somewhere at 10,000+ feet, it's for backpacking, spring ski touring trips (think base camp in a valley, not traversing ranges), and general purpose adventuring. I don't foresee riding out nasty storms for days on end in this bag, I'm more inclined to wait for better weather.

I could see the benefit of a highly water resistant shell in a 0 degree or colder rated bag, but I'm likely going to go with a 15 degree option where the weight penalty of the heavier shell is more significant in terms of overall bag weight.

There's definitely no need for a custom shaped/dimension-ed bag for someone my size, but I also dislike feeling restrained in a sleeping bag, so I'm waffling on shapes. The 5 or 10 degree options from FF and WM have cuts that are comfortable width-wise, but those bags are probably going to be uncomfortably hot for some of my uses. My current bag is 63 inches wide at the shoulders, and I could see going an inch or so smaller, but I definitely don't want something 3-4 inches narrower across my chest. I'm not terribly broad, but I do enjoy doing the YMCA in my sleep. I suppose a roomy cut 15 degree bag would be nice on warmer nights, while also allowing for ample layering if I wanted to push it and use it when it was going to be cold.

[Norseman]

Re. temp rating and bag cut... I figure that I'll be carrying a puffy, merino johns, and a beanie pretty much everywhere I camp, which can make comfortable the actual rated temp or a little lower... but for warmer summer temps I like being able to wear nothing in the bag.

It was this balance that led me to the FF 20 deg line for the all-around bag, which comes in three widths (Hummingbird, Swallow, Swift) and the lighter 10-D fabrics.

Edit: just re-read your last post... realized I missed the last sentence the first time. Sorry to just basically rehash.

[Conundrum]

Do you fart a lot? Do farts bother you? Answer those two questions before buying a new bag.

[glademaster]

Do you fart a lot? Do farts bother you? Answer those two questions before buying a new bag.

Yes, yes I do. Whose farts? I generally get a kick out of my own, particularly if there's a captive audience, excuse me, tent mate around to share the olfactory and auditory bounty with.

[bfly]

One more thing to think about, EN temperature ratings are no where near the same as ratings were back in the day (or from established manufacturers who don't use the EN rating system). A 15 degree EN rated bag may be the same as a 25 degree bag that doesn't use EN rating.

It looks like FF and WM don't use EN ratings so no worry there if that is the way you go. From WM, "We have also EN tested our bags. In every case the EN rating is lower than our posted rating. This means our ratings are more conservative."