Windshirts and warmth

[Linda Alvarez]

Ok, I'm new to the idea of windshirts but having read far too many threads on these message boards I'm more and more intrigued by the idea. However, I still have a few questions and would love some clarification from those who use this piece of gear.

1) Does a windshirt add any appreciable warmth in a sitting-around-camp situation, or is its value more in adding warmth (and water resistance) and preventing condensation under physical exertion? What about to a sleeping system?

2) if the answer to either of the above is "yes" then how do you size it for layering when also using a down sweater/jacket? would you buy one small enough to go under a parka (over your base layer) or large enough to be layered over the down and not compress it? Or am I missing the point that those are mutually exclusive layers i.e. you'd wear windshirt as your outermost layer when moving (assuming dry conditions) and then when you are in-camp you'd switch it out for down?

My questions presume three season+ shoulder conditions (I'm rarely out past October). I have recently traded an old heavy-but-warm down parka for a much lighter version but sacrificed some warmth in the process. I use a parka with my 32 degree bag to supplement when I'm expecting temps down to the 20s. (I'm a very cold sleeper and will wear everything but the kitchen sink to bed when temps get low). If a windshirt would help add back some sleep-system warmth on top of it's main purpose , I'd consider that a no-brainer addition to my arsenal, but I'm not sure whether these garments are intended to provide warmth by themselves when there is little or no convective cooling (i.e. in a sleeping bag or in camp without significant wind). Since they are made to vent air from your body to the outside, I am not sure if/how they would provide any insulating value in a clothing/sleep system.

[William Johnson]

Linda,

My apologies in only being able to give you some personal experiences with wind shirts, which isn't as precise as the data many other members might be able to provide you here.

Disclaimer aside, in answer to your first question I would say that my wind shirt (usually a Montane Featherlight, or in other cases my Rab Momentum rain coat) doesn't seem to add any heat but protects from conductive and convective heat loss. In the case of my Montane, it certainly does not seem to protect from condensation. I do not like pit zips, or venting pockets, and so take my wind shirt off when I start to heat up. For me, heating up means I will sweat, hehe.

Since that is a "yes" to question 1, I have found that my Rab rain coat is too form fitting to layer over my down jacket (a New Balance Fugu.) Luckily, my down coat is wonderfully wind resistant already, so I needn't layer anything over it. When I do squeeze my down coat underneath a rain or wind jacket, I notice loss of heat probably due to it lessening the insulative area previously available. I am sure someone knows the science here much better than I. :)

I would say that during the winter (you mentioned wind jackets only for 3-season) that my absolutely favorite set-up is a lightweight wool baselayer (150 weight merino wool Icebreaker) with a wind shirt over that. Those two together keep me wonderfully warm, and I usually add or remove the windshirt to regulate temp when moving and resting. I wear a puffy beanie and insulative gloves when resting mostly, and my down coat when at camp and sleeping.

So, I am all for you wearing the wind jacket in the winter time. My winters are relegated to CA forests (Yosemite, Tahoe, Joshua Tree.) I do prefer wearing a long-sleeved shirt under my wind jacket, though. If I am wearing a t-shirt, and put on my wind jacket, I will get cold when it brushes against my bare arms.

Good luck!

[James Moughan]

You could gain some warmth in camp by sizing your windshirt to fit over your insulation layer; it would add less warmth underneath, although not zero IME.

Personally I wouldn't do that, because having excess fabric flapping in the wind is colder, noisy, and potentially dangerous. Then again I live in a country where being blown off mountains is a serious cause of deaths among walkers, so YMMV.

[Mike M]

I think they do add warmth, but as mentioned above not as a typical insulating layer would, I'm sure the clo value for a windshirt is quite low, but that doesn't diminish the fact that that they do add (or probably more properly- contain) warmth when layered over whatever you happen to be wearing (including your noggin w/ a hood)

they are so multifunctional, that at 4 oz I can't think of a good reason to keep it out of my kit- they obviously block wind (which can have a large impact on how warm you are), they breathe well which means you can wear them on the move, they stop biting insects, for light rain it's all you need (they dry incredibly fast too)- I wear mine occasionally as part of sleep system as well

Mike

[Aaron Reichow]

They don't add warmth. They do, however, keep the wind off. This can make you feel a little warmer, if there's a cool wind. Something like the Patagonia Houdini I can wear a lot longer in hot conditions than anything that is truly adding warmth, like a fleece, mid/heavy base layer, etc. In some ways, a windshirt seems to help me feel a little cooler- I assume because the sun's rays aren't being absorbed directly by my skin. A windshirt/shell can also help with warmth if you have a very breathable insulative item like fleece or a heavier base layer- prevent air from circulating fast enough to steal your heat, and it starts to accumulate. IMHO, a base layer like the Patagonia Cap 2 is great for that- cool when it's hot, but toss a windshirt or shell over it and it is a good combo for cool temps.

[Brendan Swihart]

I'd also consider a windshirt one of my favorite layers. I made a hooded one from M90 with a liberty ridge pattern and love it. Cheap, easy project with a final weight under 2.5 oz. I find it definitely improves the warmth of puffy insulation underneath and I sleep in mine fairly often.

[James holden]

windshirts are supposed to go exactly what they say … keep most of the wind off you … wind reduces warmth ….

they should also be highly breathable and decently water resistant … they should NOT be warm … that is what layering is for

the question is how much do you sweat when active … if you dont sweat much a windshirt is fairly useless… use a highly breathable rain jacket instead that youd cary anyways

if yr a sweaty ole pig like me … they are gods gift

oink oink!!!

[James Moughan]

A windshirt adds warmth whether or not there is any wind, by trapping a layer of air between it and the next layer. It's the same principle as fleece or down, windshirts are just less effective at reducing air movement.

[Steven McAllister]

Some of my experiences:
Warm spring day wearing one of those typical thin meshy Champion sports jerseys that are designed to be cool. When the sun went down and the temperatures dropped I pulled on the wind shirt. It felt easily 10 deg. F. warmer. The windshirt blocked the breeze from sucking body heat away and allowed the mesh shirt to trap air.

I often wear a light grid-fleece. It is highly breathable and not warm as air can blow right through it. Put a windshirt on top and the combination takes me down below freezing while hiking, without much dampness.

Most windshirts can be worn instead of a rain-shell in light to moderate rain, if you wear synthetic layers inside. Much more comfortable in drizzly weather as you get less trapped moisture inside.

I very rarely wear a rain shell in the NorthEast. Heavy sheeting rain is the exeption.
I have hiked all day light showers this way. Sure my fleece layer gets a little damp, but because it is hydrophobic and highly breathable it doesn't feel clammy under a windshirt.

I am one of those people that swear by the combination.

[Mary D]

I originally bought a windshirt because horseflies and deerflies were biting right through my permethrin-treated hiking shirt. I figured the windshirt was the only reasonable substitute for what I really felt I needed, a suit of medieval armor!

Since then I've discovered that my windshirt is the most versatile garment I own. I wear it more than any other piece in my "clothing carried" list.

The windshirt is the item I reach for most often at rest stops/lunch breaks/upon arriving in camp. Often the temps in the high mountains (Cascades, Rockies) are borderline, with just enough breeze that I'm not warm enough in just my shirt when I'm sitting still. It's not insulation, but it blocks the breeze so that I'm comfortable (no convective or evaporative cooling). And, of course, it's when I stop that those nasty flies show up!

On cold days (down to mid-20's F), the windshirt over a base layer is the perfect clothing while I'm actively hiking–I'm warm enough but not sweaty. As it gets colder (below 40*F), I'll add a lightweight pair of gloves and a Smartwool headband. If it gets colder than the 20* F, I add a lightweight mid-layer (lightweight fleece vest). The windshirt is a good supplement to my insulating jacket during rest stops or in camp under these same conditions. Yes, the windshirt and the shell of my Montbell Ex-Light down jacket are of the same material, but the shell of the down jacket has a lot of holes sewn through it, while the windshirt doesn't.

I have often used the windshirt inside my sleeping bag. Either I just want a little something that's a little warmer than a baselayer top, or it's so cold that I want to wear everything I own!

All that for 2.4 ounces….

[Author]

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