Windshirt – form-fitting vs sized over down jacket

Depends I guess on the weather you are preparing for Even an XXXXL windshirt weighs so little that I can see sense in making both

> “I’ll never really wear it that way”

Then don’t size it that way.

It makes more sense to oversize your rain jacket to fit over everything rather than a windshirt. Rain jackets are ideal to wear around camp because they don’t breath well and you’re not working out in camp. Windshirts are ideal for active hiking in cool conditions, so I like mine to be form-fitted.

It’s good to have just enough room for 100 wt fleece and a balaclava underneath a windshirt. Also helpful to have a hood for the windshirt – lots of warmth retention for the weight while hiking. With that combination I can hike comfortably in near zero, windy weather above treeline, provided that I have enough hand insulation and warms socks. I also like to wear the windshirt sleeping – it’s nice and slick under a grabby pyramid mosquito net and it helps keep the stink factor out of my quilt and down jacket.

As Lester said a wind shirt is an active layer so being able to fit it over a puffy isn’t the priority, however it is an active layer so you need full range of motion.  Most wind shirt material has limited stretch, if any, so they need to be cut and sized to allow range of motion and not rely on the fabric to give.

I use a Squamish, which has some nice stretch and is roomy enough to not limit range of motion. As a result it fits over my puffy layer.  It also has some nice features to adjust the fit (velcro cuffs and draw strings) so you can go with a little looser fit without losing the functionality of blocking drafts.

Argon 90 is not downproof. The air permeability is about 40 cfm. This is appropriate for active wear not for static insulation.

I prefer a highly permeable (like Argon 90), relatively close-fitting windshirt to reduce flapping and snagging on stuff. I wear over base and, at most, 100 wt fleece. I put my rain jacket (CFM ~ 0.5) over down puffy in static situations.

If I made a lot of fires I would rethink this.

[weird script removed – MK]

Correction, Argon 90 IS downproof and was actually designed around being used for quilts.

Hoosier,

Hmm, must be a different Argon 90. I was thinking of the one Richard Nisley tested at ~40 CFM: https://backpackinglight.com/forums/topic/100458/#post-2177297 I was under the impression that a fabric needed to be about < 10 CFM to be downproof.

Nope it’s the same stuff. Argon 67 and 90 are both calendered and are rated to be very down-proof. It’s likely their weave and/or dwr that allows them to be so breathable while also being sufficiently down-proof. Regardless, a number of cottage manufacturers utilize these materials for down quilts and garments and report no issues with down leakage. I.E. Luke’s Ultralight, HammockGear, LocoLibre Gear.

If it’s the same fabric that Richard Nisley tested at 40 CFM it’s too permeable to be of much help to protect the down jacket from the wind. If both the down jacket and windshirt have 40 CFM outer fabrics, the system will have a combined air permeability of 20 CFM. Considering that a typical down jacket has outer fabric half as permeable, I would consider using a rain jacket to protect the down jacket from wind and getting the wind jacket sized to fit over base + midlayer and use it for hiking rather than static situations.

I bought a wind jacket a little loose thinking it would be more versatile… fit over a puffy, possibly protect it. regret that decision and never wear it. Too flappy, which is annoying in the wind or when pockets sag, and can be drafty.

find a jacket that is cut right fit your body and a closer fit will still offer coverage and movement.

If both the down jacket and windshirt have 40 CFM outer fabrics, the system will have a combined air permeability of 20 CFM.

How do you get to that figure?

I chose to go both ways, to have a size large wind shirt to put over a vest or 100 wt. fleece layer, and an XL to wear over my puffy down parkas to protect them from snags or campfire embers. If it’s really cold, like when snowshoeing, I might put a Gore Tex shell over everything at rest/lunch stops for more warmth.

For me, I’d size it to go over the fleece. No reason you can’t wear a windshirt under a down jacket for extra warmth.

How do you get to that figure?

Richard Nisley taught the forum this some years ago. I tried to find that post and the closest I got is this post referring to it: https://backpackinglight.com/forums/topic/70722/page/2/#post-1931448

Unfortunately, the link to the actual post is broken.

I do remember how to calculate, however: add the inverse of the two layers and then flip back over:

E.g. one layer 20 CFM and another layer 40 CFM -> 1/10 + 1/40 = 4/40 + 1/40 = 5/40 -> 40/5 CFM = 8 CFM

This example shows how little additional wind resistance is gained when a 40 CFM layer is worn over or under a 10 CFM layer.

Windshirts vary a great deal, with air permeability ranging from ~ 1 CFM to 70+ CFM (e.g. the outer layer of Patagonia’s Nano Air stuff).

I highly recommend Richard Nisley’s threads and posts on this topic:

https://backpackinglight.com/forums/topic/87696/

https://backpackinglight.com/forums/topic/patagonia-airshed-pullover-review/#post-3451714

I would wear a windshirt with base layer and fleece for active cold weather and put my puffy on over the whole works for quick rest stops and take the windshirt off in camp. I like a roomy rain shell anyway and it will add another layer of warmth over a puffy as well as protect it from rain, although that would be in cold rain conditions like standing around in camp in 35f rain and I would be in my shelter pretty quick!

A shell over a puffy might compress it a bit, but that is moot as it gets colder and there’s no precip and a rain shell isn’t used

I would probably size it to fit over a base layer or mid weight fleece.

My hardshell is usually sized to fit over everything, not my windshirt.