Subscribe Contribute Advertise Facebook Twitter Instagram Forums Newsletter
Current UL windshirts and breathability: are there other options and layering techniques?
Display Avatars Sort By:
Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: Re: Layering techniques on 02/26/2014 12:00:29 MST Print View

Hey Dale:

I am sure sorry if I came off as saying "everyone is wrong"; in fact the reason I read these crazy threads is exactly because I am interested in learning from users here. Is my opinion less valid than anyone else's just because of my day job?

As for your assessment of Sierra Designs, I actually agree with you more than disagree. Working on it.......

Justin Baker
(justin_baker) - F

Locale: Santa Rosa, CA
layering over on 02/26/2014 12:38:37 MST Print View

I get that layering a fleece over a windshirt will keep the fleece dry because it's able to release moisture without being underneath a less breathable windshirt over it. I have a fleece hoody that I pull over my windshirt during breaks for convenience. However this only makes sense if it's not windy. If it's not windy, your wind shirt really isn't acting as a windshirt, it's an ultralight insulative shirt.
Layering over a puffy is different because puffy shell materials are typically wind resistant.

By the way Micheal, your kenosha jacket fabric is the most breathable windshirt fabric I've ever handled. I would wear mine more if it had a hood.

Matt Dirksen
(NamelessWay) - MLife

Locale: Mid Atlantic
Re: Sala's testing: and challenging the conventional wisdom on 02/26/2014 14:43:56 MST Print View

Hi Michael:

While I have used my (high CFM) windshirt in the exact way that you have suggested with very good results (ergo: "shirt"), I got hung up by something you said.

You said: "what we should really call it is a "semi-permeable vapor barrier"

In my profession (architectural), this is very confusing language to me. It is generally accepted in the building world that a "vapor barrier" (.1 perm or less) is never actually "semi-permeable", because it is simply a vapor barrier. Nowadays, a vapor barrier is commonly referred to as a "Class 1 vapor retarder"

I believe you probably mean "a semi-permeable vapor retarder", but this discussion about layering techniques has primarily been about the air permeability of various layers, not vapor permeability.

These two forms of vapor transport are not the same, in my opinion, and I believe that when we start talking about how to stay warm and not "overheat", the CFM measurement of a jacket is only part of the picture. (Even the word "overheat" can be considered misleading, since "overhumidify" may be equally relevant, and treated differently than overheating.)

I know there might be differing opinions about these definitions, and some may not care whatsoever, but in my 18 months on this list I have witnessed more confusion around vapor/air permeability than anything else. I think it might be due-in-part to people writing sharing their experiences using terms that all us readers interpret differently.
Perhaps its time we create our own "BPL list of snazzy terms" that we can all agree upon!

Although solely related to building science, here is a wonderful resource with many documents on the subject of vapor/air permeability:

For what it's worth, all this conversation about the "BEST" layering techniques reminds me of how to properly use manual transmission in a car. Once, I witnessed a conversation about what cars have the "best gear shift ratio", and answer that always seemed to show up was: "it depends on the road".


Eugene Smith
(Eugeneius) - MLife

Locale: Nuevo Mexico
Re: Re: Re: Layering techniques on 02/26/2014 15:13:37 MST Print View

Good night man, y'all are some uber alpine athletes here or I'm just way out of touch these days. If I stumbled across this thread I would be under the impression this is a forum for self supported aerospace exploration. I understand the purpose in challenging conventions here, but how much performance do you expect from your windshirt? For f@%ks sake!

"Less gear, more beer!"

Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: Re: Sala's testing: and challenging the conventional wisdom on 02/26/2014 15:13:55 MST Print View

Great points, Matt. The term "semi permeable vapor barrier" was simply made up, by Mark Twight, I believe. And I am honestly unsure about the differences or similarities in the definitions of Vapor Barrier in construction and outdoor gear, the latter usually focused on completely impermeable barriers inside of boots or sleeping bags. But I will check out your article and try to educate myself. Heres a link to a useful article on the latter:

I agree there are all kinds of various terms that get thrown around without specific definitions. It sometimes makes it hard to understand the exact point someone is trying to make. Nevertheless, I find the discussion and particularly the passion surrounding it infectious.

Edited by gmontlake on 02/26/2014 15:15:41 MST.

Dave -
(FamilyGuy) - F

Locale: Up there
Re: Re: Re: Re: Layering techniques on 02/26/2014 15:46:11 MST Print View

Eugene - Best. Post. Ever.

Matt Dirksen
(NamelessWay) - MLife

Locale: Mid Atlantic
Re: Re: Re: Re: Layering techniques on 02/26/2014 15:58:51 MST Print View


Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: layering over / Kenosha Fabric on 02/26/2014 16:52:28 MST Print View


I LOVED that Kenosha fabric too, and actually have one with a hood. But ironically, given your statement, we dropped it because the CFM was too low (measured at .9CFM). But still, I had the same experience as you, so I looked in to the other specs, thinking maybe it had low air permeability but high MVTR that made it feel more breathable than the air permeability alone would indicate. And that is exactly the case. But our new custom milled fabric is even better on that spec. Here is the breakdown of the Kenosha (2013 fabric) vs. our custom milled Stow Winshirt fabric for 2014.

Moisture Vapor Transfer Rate: 44,000g (JIS L1099-B1) or 4,600g (ASTM E96BW)
Air Permeability: .9CFM (ASTM D737)
Water Entry Pressure: not measured

Moisture Vapor Transfer Rate: 53,700g (JIS L1099-B1), or 6,750g (ASTM E96BW)
Air Permeability: 3CFM (ASTM D737)
Water Entry Pressure: 380mm (permanent, due to kiss coat of PU vs. DWR on the Kenosha)

I have not extensively used the Stow jacket, but based on the numbers, if you loved the Kenosha, you would love the Stow even more, especially since it has a hood. However, though it has a nice hand and next to skin feel, it is not nearly as nice as the Kenosha, which feels almost as good as cotton next to your skin after a couple of washes (when all the DWR is gone).

It's always something......

Patrick M.
Re: Sala's testing: and challenging the conventional wisdom on 02/27/2014 15:58:45 MST Print View

Michael Glavin,
I'm listening, and willing to try new ideas. What is this idea you mention at the end?

I will try experimenting with the skin layer on tonight's walk. Not exactly high aerobic, but enough so that I have found a cheap laminate softshell stifling and sweaty.

Is this a good sample setup?:
Base layer of silk, polypro, grid fleece, cotton, or light merino
"Skin" layer of Frogg Toggs Class Pro Action suit. Standard 3L goretex is possible as alternative...
outer layer of 200-300wt fleece or wool felt

Edited by patrat on 02/27/2014 16:00:29 MST.

Rob P
(rpjr) - M
Did this Last night as well on 02/27/2014 16:36:14 MST Print View

I did this last night on my walk…6 degrees f, -10f windchill. Here is how I layered.

Baselayer: Cabela's thermal zone zip neck

Windshirt: Arcteryx Squamish (the less breathable of the two that I own)

Fleece: Eddie Bauer Cloud layer fleece

I was pretty cold when I started, but was comfortable at the end.

I'm going to wear two fleeces instead of one atop the wind shirt tonight. I would wear my Rab Generator Jacket or my WM flash XR atop the wind shirt but I don't know if they are more breathable than the Squamish.

Right now it's 7, windchill -3, so we'll see what happens.

Rob P
(rpjr) - M
Walk on 02/27/2014 17:52:01 MST Print View

OK…just got in. I layered Identically to last night, except I put on an a 100wt fleece over the Eddie Bauer fleece. Temp when I came in was 4f, windchill-5f.

Unlike last night, I perspired. I think I had the optimum amount of insulation on last night. I could have taken the extra fleece off tonight, but I wanted to leave it on for the sake of experimentation (I'm not a scientist though, so I'm only reporting my very subjective impressions).

I felt a little clammy…I think I could have avoided this by slowing down or by taking off the extra fleece. When I came in, I took off the outer fleece and it was a little damp on the inside. I took off the inner fleece, and it was dry on the inside. I took off the wind shirt, and I could tell that it had been a little damp. Baselayer felt ok. My skin was more dry than I thought it would be.

I'd like to use a lighter base layer tomorrow night…either a Capilene 2 or an Aclima Coolnet or Woolnet long sleeve. If the temp is similar, I'll wear the two fleeces again to see if I feel less clammy with a base layer that isn't so thick.

Michael Gillenwater
(mwgillenwater) - M

Locale: Seattle area
Re: Re: layering over / Kenosha Fabric on 02/27/2014 20:59:37 MST Print View

Glavin, I just want to say thank you for your constructive and polite input to this forum. It is appreciated by many of us. It would be really nice to have substantive technical input from gear manufacturers on more forums here.

And you have me more interested in the Stow fabric now. Just need to be convinced on the PU coating idea. If it is so great, why isn't it used by everyone?

Edited by mwgillenwater on 02/28/2014 20:55:49 MST.

Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: Re: Re: layering over / Kenosha Fabric on 02/27/2014 22:35:53 MST Print View

I honestly don't know.

Our Product Director (Jim Trombly, formerly Alpine Director at Patagonia) is especially passionate about ensuring lasting water resistance, as he thinks (like many here) that wind shirts need to be built to push into a light rain event. He hates the Houdini for this reason. This was a custom milled fabric that he and Martin developed to have maximum MVTR with 2-5CFM and permanent rain resistance. And so the kiss coat made sense. At just over 300mm of water entry pressure, it is a VERY light coat that you cannot really even tell is there. There is also the cost of running the fabric through the coating process, only to add a minuscule amount of PU, which might be a factor since most would not add the cost for something that 99.9% of folks would not notice on the shelf.

It is also in more fabrics than you might think. It is a fairly common treatment vs a cire for down-proofing wovens. In Fall 14 all of our down jackets will use this since it actually allows better airflow and moisture transfer than calendaring, with superior water entry pressure (WEP) IF you know what you are doing and test the fabric properly. (Cire finish is where you heat and melt the fabric to make it smooth; this has the effect of filling in the holes between the yarns, and is one common way to make a fabric down proof. It also cuts down the CFM, MVTR, etc, and adds to the WEP).

Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: Walk on 02/27/2014 22:56:05 MST Print View

Rob: Very interesting. Thank you for your insight. Your second test, where you overwhelmed the system, is very interesting. First, I am theorizing that it was not very windy, or I would think that the moisture would have aired out in that fleece. Maybe it froze before getting far enough out of the fleece to evaporate?

We have all been thinking that fleece has way too much air permeability to be effective as the outer layer in wind, but I too tried it last night (boy was it hard to find fleece in my house). I think we might be more wrong than right. I wore a wool zip-T with a Kenosha wind shirt and a cotton (yes, cotton) sweatshirt over the top. I don't know the CFM of a cotton sweatshirt, but I would guess it to be about 100CFM if not a little more. My wool got wet, naturally, in the normal places, but the wind shirt remained relatively dry (damp near the wet places on the wool), but surprisingly, the cotton stayed dry. Well, dry"isn" might be a better description. It fit not have any wet spots, but felt "humid".

I have been searching for an insulating 30-50CFM stretch material for the "over" layer for winter, and now I am wondering if higher air permeability is actually more desirable - even in the wind. Think about it, your fleece eventually held the water, and you obviously had some air movement given the difference between temp and wind chill above. A lower CFM garment would have been worse.

Of course, in your case, you would have lost the outer layer in a non-test situation, but in my case I never felt too hot so I just kept going. (It was mid to high 20's in Spokane, I think (I did not check). But in your case, a lower CFM garment would have surely held more moisture.

Next time lets maybe try starting out with the base layer and insulating layer underneath, work to a mid temperature level where the interior layers are getting wet, then put the outer insulating layer over the second skin and see what happens. If the system were to actually dry, that would be side by side evidence.....

Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: Re: Sala's testing: and challenging the conventional wisdom on 02/27/2014 23:23:35 MST Print View


I don't know the air permeability of Frogg Toggs, but my understanding it that all of their materials are "waterproof/breahable", which almost guarantees that they will have virtually no CFM. In this case, just like any Gore Tex Jacket, you will be relying solely on the MVTR (moisture vapor transfer rate) of the fabric to move moisture. And if it is like Gore Tex or other waterproof/breathables, that won't be much. I have tried drying gore tex under fleece in rain, and it actually works (though the fleece gets wet obviously), and with a dryer outer fabric the laminate will allow much more water through. But either of these suits seems pretty steamy under any conditions. A tightly woven polyester work shirt would probably be a better "second skin" than a waterproof/breathable, and would have a higher CFM than what I have come to use, but which has been suggested as superior in this thread. i was going to try the same, honestly. I have a 50CFM (estimate; SGS testing still underway) hoodie that we are testing for S15, thinking it more of a high exertion bug/sun/light windbreaker layer. But now I am going to try that as the under layer during my stair climb, then switch to the .9CFM kenosha and see what happens.

The idea I mention at the end is a different way of dealing with external precipitation. In the system I have been advocating, if layers over the second skin get more and more air permeable, it is hard for me to imagine (with current thinking) how those layers are not going to get more and more susceptible to external moisture, as has been repeatedly suggested here. So this idea is based on the same GO/STOP/RAIN system advocated by the Cloud Layering System, where you carry an ultralight rainshell system for use ONLY during external precipitation events. I believe that this is the best system for backpacking, where unlike a day hike you really want to avoid the full on soak if you can, especially up here in the PNW where at least one "all day rain hike" is a reality on nearly every longer backpacking trip. So basically, it is an ultralight rain system, the entire prototype suit weighs less than 8 ounces in 20D fabric (and at that weight it provides the same head to toe protection of a traditional jacket and pants). It does not rely on the MVTR of the fabric to evaporate moisture, like GoreTex, which in my experience is Guaranteed to Keep You WET when hiking hard in the rain. Send me an IM and I will tell you how to make one to test the concept......

Rob P
(rpjr) - M
Re: Re: Walk on 02/28/2014 13:58:57 MST Print View


I thought it was interesting that the fleece I wore right over the wind shirt was completely dry. The outer fleece was a little damp. I think that if I had stayed out a little longer maybe the outer fleece would have dried out as well.

By the way, the outer fleece did not freeze, it was only damp on the inside, not on the outside.

Also, you are correct that it was not as windy.

Regarding "overwhelming" the system, I was trying to do that on purpose…I would have been very comfortable by just removing the outer fleece, just as I was the night before.

As far as next time, just to see if I'm understanding you correctly, I should wear base layer, 2 fleeces, and then wind shirt on top until I work up a little sweat…Once that happens, remove the wind shirt and fleeces, put wind shirt over base layer and then fleeces over the wind shirt?

Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: Re: Re: Walk on 02/28/2014 14:59:29 MST Print View

Hey Rob:

No, I was suggesting that we try putting the fleece under the second skin for the first half of the workout, then taking it off and putting it on the outside for the second half, and seeing if the system is drier at the end while maintaining warmth. It's the best way I can think of to do a "side by side" comparison. We have done this on our "sweat dummy" in the ADC, but that lab test has no wind and the dummy can't feel......

Dale Wambaugh
(dwambaugh) - MLife

Locale: Pacific Northwest
Re: layering conclusions on 02/28/2014 15:40:52 MST Print View

I see the following combinations being examined here:

Base layer: active, not cold, not windy

Base layer/wind shell: active and cold/wind/light precip, less active and rest for cool/wind/light precip

Base layer/wind shell/puffy: for colder rest. I could see making a case for replacing the puffy with a soft shell, again for rest, but not for active stuff. I don't consider soft shells as weight/warmth effective for UL hiking use anyway. They are trumped by lighter puffies or fleece/wind shell combinations, but I could see just throwing on on top of my windshirt for quick and easy layering and not getting a cold blast trying to change layers. No way I could hike with that combo.

I get those and they make sense. What does puzzle me is the base/wind shell/fleece, in that the fleece is porous and won't block wind but will provide loft and breathability when used under the wind shell. It would have to be quite cold for me to use a base/fleece/wind shell combination when active and outside most three season use. Definitely in the quiver for three season rest stops and camp use, especially in wet weather. I wouldn't want the fleece on the outside with any kind of precip-- that defies any common sense IMHO.

Make sense?

Michael Glavin
(gmontlake) - MLife

Locale: Cascades and Selkirks
Re: Re: layering conclusions on 02/28/2014 16:52:37 MST Print View

Makes sense to me. The obvious flaws in "fleece" over windshell are wind and moisture. In terms of wind, I have always tried to approach this with a lower CFM garment than the wind layer, but not so high as fleece. What I am starting to suspect, though, is that this deficiency is not nearly what one might assume. Yes, the wind can cut right through it and steal trapped warmth, but that serves to dry it too, and the wind layer underneath guarantees that you won't feel the "flash off" due to evaporative cooling, since it happens on the outside. In a driving consistent wind, it still seems like super high CFM materials like fleece may allow too much airflow, and all the heat you put there is immediately stolen. But in most wind situations, I am wondering if the drying affect offsets the temporary heat loss, which the heat of the consistent engine underneath the second skin quickly replaces.

The second flaw, moisture, is the one that is currently the topic of heated debate at SD. For me, though, 99% of the time the issue is moot, since a base layer/wind layer is all most folks ever need in above freezing temperatures when on the go. Then when they stop, say at 35 degrees, they can just put on a down puffy for the rest session. So the wind wear is always on the outside during a light rain event. But in colder temps, or lower exertion activities, external moisure is the issue. To me, the best way to deal with this is to use uber light storable rainwear that you use ONLY when it is raining or otherwise introducing external moisure (bushwhacking in wet brush, etc.) Just like the Cloud Layering System. This works regardless of the air permeability or water resistance of the outer layer, in all situations. The problem is that this TOTALLY kills the system by putting a 0FM low MVTR layer on the outside. The two ways to solve this are to find high CFM layers that have significant water resistance (so far, I have come up with nothing there), OR to make that "rain layer" have a high CFM and high MVTR (as GoreTex, Event, Neoshell etc. try and fail miserably to do). But there is another way, that while not perfect, is the best way that I have ever found to stay relatively dry hiking hard all day in the rain. Don't rely on the breathability of the fabric, rely on airflow UNDER the fabric. Like a tent. But not all floppy like a poncho. To me, solving the ultralight rain piece allows the rest of the system to work. But ONLY if you accept the premise that this goes on in the wet and off when its dry, and the rest of the system works independently. That challenges the "push the wind wear into light rain" point of view. I can see the benefit of that point of view on a day hike. But while backpacking, I am a believer that you need good rainwear, so to me that system is the best way to stay warm and comfortable at the lowest possible weight in any conditions, which is pretty much the goal of mostly everyone, except the extreme who don't care about comfort and are just pushing for survival only.

Michael Gillenwater
(mwgillenwater) - M

Locale: Seattle area
New Prolite video on wind shirts on 03/25/2014 13:42:17 MDT Print View

I thought this was great. And it up'ed my opinion some of the new Houdini fabric. I'm digging it in the Nine Trails jacket right now for trail running.